Publish Canary

- vercel@19.1.2-canary.14
 - @vercel/node@1.7.2-canary.1
 - @vercel/static-build@0.17.5-canary.0

.editorconfig

@@ -19,6 +19,11 @@ indent_style = space
 [*.py]
 indent_size = 4
 
+[*.go]
+indent_style = tab
+indent_size = 4
+tab_width = 4
+
 [*.asm]
 indent_size = 8
 

.github/CODEOWNERS

@@ -1,27 +1,27 @@
 # Documentation
 # https://help.github.com/en/articles/about-code-owners
 
-*                                        @tootallnate
+*                                        @TooTallNate
 /.github/workflows                       @AndyBitz @styfle
 /packages/frameworks                     @AndyBitz
-/packages/now-cli/src/commands/dev/      @tootallnate @styfle @AndyBitz
-/packages/now-cli/src/util/dev/          @tootallnate @styfle @AndyBitz
-/packages/now-cli/src/commands/domains/  @javivelasco @mglagola @anatrajkovska
-/packages/now-cli/src/commands/certs/    @javivelasco @mglagola @anatrajkovska
+/packages/now-cli/src/commands/dev       @TooTallNate @styfle @AndyBitz
+/packages/now-cli/src/util/dev           @TooTallNate @styfle @AndyBitz
+/packages/now-cli/src/commands/domains   @javivelasco @mglagola @anatrajkovska
+/packages/now-cli/src/commands/certs     @javivelasco @mglagola @anatrajkovska
 /packages/now-cli/src/commands/env       @styfle @lucleray
-/packages/now-client                     @rdev
-/packages/now-build-utils                @styfle @AndyBitz
-/packages/now-node                       @styfle @tootallnate @lucleray
-/packages/now-node-bridge                @styfle @tootallnate @lucleray
+/packages/now-client                     @rdev @styfle @TooTallNate
+/packages/now-build-utils                @styfle @AndyBitz @TooTallNate
+/packages/now-node                       @styfle @TooTallNate @lucleray
+/packages/now-node-bridge                @styfle @TooTallNate @lucleray
 /packages/now-next                       @Timer @ijjk
-/packages/now-go                         @styfle @sophearak
-/packages/now-python                     @styfle @sophearak
-/packages/now-ruby                       @styfle @coetry @nathancahill
+/packages/now-go                         @styfle @TooTallNate
+/packages/now-python                     @styfle @TooTallNate
+/packages/now-ruby                       @styfle @coetry @TooTallNate
 /packages/now-static-build               @styfle @AndyBitz
 /packages/now-routing-utils              @styfle @dav-is @ijjk
 /examples                                @mcsdevv @timothyis
 /examples/create-react-app               @Timer
-/examples/nextjs                         @timneutkens
+/examples/nextjs                         @timneutkens @Timer
 /examples/hugo                           @mcsdevv @timothyis @styfle
-/examples/jekyll                         @mcsdevv @timothyis @sarupbanskota
+/examples/jekyll                         @mcsdevv @timothyis @styfle
 /examples/zola                           @mcsdevv @timothyis @styfle

DEVELOPING_A_RUNTIME.md

@@ -1,10 +1,33 @@
 # Runtime Developer Reference
 
-The following page is a reference for how to create a Runtime using the available Runtime API.
+The following page is a reference for how to create a Runtime by implementing
+the Runtime API interface.
 
-A Runtime is an npm module that exposes a `build` function and optionally an `analyze` function and `prepareCache` function.
-Official Runtimes are published to [npmjs.com](https://npmjs.com) as a package and referenced in the `use` property of the `vercel.json` configuration file.
-However, the `use` property will work with any [npm install argument](https://docs.npmjs.com/cli/install) such as a git repo url which is useful for testing your Runtime.
+A Runtime is an npm module that implements the following interface:
+
+```typescript
+interface Runtime {
+  version: number;
+  build: (options: BuildOptions) => Promise<BuildResult>;
+  analyze?: (options: AnalyzeOptions) => Promise<string>;
+  prepareCache?: (options: PrepareCacheOptions) => Promise<CacheOutputs>;
+  shouldServe?: (options: ShouldServeOptions) => Promise<boolean>;
+  startDevServer?: (
+    options: StartDevServerOptions
+  ) => Promise<StartDevServerResult>;
+}
+```
+
+The `version` property and the `build()` function are the only _required_ fields.
+The rest are optional extensions that a Runtime _may_ implement in order to
+enhance functionality. These functions are documented in more detail below.
+
+Official Runtimes are published to [the npm registry](https://npmjs.com) as a package and referenced in the `use` property of the `vercel.json` configuration file.
+
+> **Note:** The `use` property in the `builds` array will work with any [npm
+> install argument](https://docs.npmjs.com/cli/install) such as a git repo URL,
+> which is useful for testing your Runtime. Alternatively, the `functions` property
+> requires that you specify a specifc tag published to npm, for stability purposes.
 
 See the [Runtimes Documentation](https://vercel.com/docs/runtimes) to view example usage.
 
@@ -16,146 +39,170 @@ A **required** exported constant that decides which version of the Runtime API t
 
 The latest and suggested version is `3`.
 
-### `analyze`
+**Example:**
 
-An **optional** exported function that returns a unique fingerprint used for the purpose of [build de-duplication](https://vercel.com/docs/v2/platform/deployments#deduplication). If the `analyze` function is not supplied, a random fingerprint is assigned to each build.
-
-```js
-export analyze({
-  files: Files,
-  entrypoint: String,
-  workPath: String,
-  config: Object
-}) : String fingerprint
+```typescript
+export const version = 3;
 ```
 
-If you are using TypeScript, you should use the following types:
+### `build()`
 
-```ts
-import { AnalyzeOptions } from '@vercel/build-utils'
+A **required** exported function that returns a Serverless Function.
 
-export analyze(options: AnalyzeOptions) {
-  return 'fingerprint goes here'
+> What's a Serverless Function? Read about [Serverless Functions](https://vercel.com/docs/v2/serverless-functions/introduction) to learn more.
+
+**Example:**
+
+```typescript
+import { BuildOptions, createLambda } from '@vercel/build-utils';
+
+export async function build(options: BuildOptions) {
+  // Build the code here…
+
+  const lambda = createLambda(/* … */);
+  return {
+    output: lambda,
+    watch: [
+      // Dependent files to trigger a rebuild in `vercel dev` go here…
+    ],
+    routes: [
+      // If your Runtime needs to define additional routing, define it here…
+    ],
+  };
 }
 ```
 
-### `build`
+### `analyze()`
 
-A **required** exported function that returns a [Serverless Function](#serverless-function).
+An **optional** exported function that returns a unique fingerprint used for the
+purpose of [build
+de-duplication](https://vercel.com/docs/v2/platform/deployments#deduplication).
+If the `analyze()` function is not supplied, then a random fingerprint is
+assigned to each build.
 
-What's a Serverless Function? Read about [Serverless Functions](https://vercel.com/docs/v2/serverless-functions/introduction) to learn more.
+**Example:**
 
-```js
-build({
-  files: Files,
-  entrypoint: String,
-  workPath: String,
-  config: Object,
-  meta?: {
-    isDev?: Boolean,
-    requestPath?: String,
-    filesChanged?: Array<String>,
-    filesRemoved?: Array<String>
-  }
-}) : {
-  watch?: Array<String>,
-  output: Lambda,
-  routes?: Object
+```typescript
+import { AnalyzeOptions } from '@vercel/build-utils';
+
+export async function analyze(options: AnalyzeOptions) {
+  // Do calculations to generate a fingerprint based off the source code here…
+
+  return 'fingerprint goes here';
 }
 ```
 
-If you are using TypeScript, you should use the following types:
+### `prepareCache()`
 
-```ts
-import { BuildOptions } from '@vercel/build-utils'
+An **optional** exported function that is executed after [`build()`](#build) is
+completed. The implementation should return an object of `File`s that will be
+pre-populated in the working directory for the next build run in the user's
+project. An example use-case is that `@vercel/node` uses this function to cache
+the `node_modules` directory, making it faster to install npm dependencies for
+future builds.
 
-export build(options: BuildOptions) {
-  // Build the code here
+**Example:**
+
+```typescript
+import { PrepareCacheOptions } from '@vercel/build-utils';
+
+export async function prepareCache(options: PrepareCacheOptions) {
+  // Create a mapping of file names and `File` object instances to cache here…
 
   return {
-    output: {
-      'path-to-file': File,
-      'path-to-lambda': Lambda
-    },
-    watch: [],
-    routes: {}
-  }
+    'path-to-file': File,
+  };
 }
 ```
 
-### `prepareCache`
+### `shouldServe()`
 
-An **optional** exported function that is equivalent to [`build`](#build), but it executes the instructions necessary to prepare a cache for the next run.
+An **optional** exported function that is only used by `vercel dev` in [Vercel
+CLI](https://vercel.com/download) and indicates whether a
+[Runtime](https://vercel.com/docs/runtimes) wants to be responsible for responding
+to a certain request path.
 
-```js
-prepareCache({
-  files: Files,
-  entrypoint: String,
-  workPath: String,
-  cachePath: String,
-  config: Object
-}) : Files cacheOutput
-```
+**Example:**
 
-If you are using TypeScript, you can import the types for each of these functions by using the following:
+```typescript
+import { ShouldServeOptions } from '@vercel/build-utils';
 
-```ts
-import { PrepareCacheOptions } from '@vercel/build-utils'
+export async function shouldServe(options: ShouldServeOptions) {
+  // Determine whether or not the Runtime should respond to the request path here…
 
-export prepareCache(options: PrepareCacheOptions) {
-  return { 'path-to-file': File }
+  return options.requestPath === options.entrypoint;
 }
 ```
 
-### `shouldServe`
+If this function is not defined, Vercel CLI will use the [default implementation](https://github.com/vercel/vercel/blob/52994bfe26c5f4f179bdb49783ee57ce19334631/packages/now-build-utils/src/should-serve.ts).
 
-An **optional** exported function that is only used by `vercel dev` in [Vercel CLI](https:///download) and indicates whether a [Runtime](https://vercel.com/docs/runtimes) wants to be responsible for building a certain request path.
+### `startDevServer()`
 
-```js
-shouldServe({
-  entrypoint: String,
-  files: Files,
-  config: Object,
-  requestPath: String,
-  workPath: String
-}) : Boolean
-```
+An **optional** exported function that is only used by `vercel dev` in [Vercel
+CLI](https://vercel.com/download). If this function is defined, Vercel CLI will
+**not** invoke the `build()` function, and instead invoke this function for every
+HTTP request. It is an opportunity to provide an optimized development experience
+rather than going through the entire `build()` process that is used in production.
 
-If you are using TypeScript, you can import the types for each of these functions by using the following:
+This function is invoked _once per HTTP request_ and is expected to spawn a child
+process which creates an HTTP server that will execute the entrypoint code when
+an HTTP request is received. This child process is _single-serve_ (only used for
+a single HTTP request). After the HTTP response is complete, `vercel dev` sends
+a shut down signal to the child process.
 
-```ts
-import { ShouldServeOptions } from '@vercel/build-utils'
+The `startDevServer()` function returns an object with the `port` number that the
+child process' HTTP server is listening on (which should be an [ephemeral
+port](https://stackoverflow.com/a/28050404/376773)) as well as the child process'
+Process ID, which `vercel dev` uses to send the shut down signal to.
 
-export shouldServe(options: ShouldServeOptions) {
-  return Boolean
+> **Hint:** To determine which ephemeral port the child process is listening on,
+> some form of [IPC](https://en.wikipedia.org/wiki/Inter-process_communication) is
+> required. For example, in `@vercel/go` the child process writes the port number
+> to [_file descriptor 3_](https://en.wikipedia.org/wiki/File_descriptor), which is read by the `startDevServer()` function
+> implementation.
+
+It may also return `null` to opt-out of this behavior for a particular request
+path or entrypoint.
+
+**Example:**
+
+```typescript
+import { spawn } from 'child_process';
+import { StartDevServerOptions } from '@vercel/build-utils';
+
+export async function startDevServer(options: StartDevServerOptions) {
+  // Create a child process which will create an HTTP server.
+  //
+  // Note: `my-runtime-dev-server` is an example dev server program name.
+  // Your implementation will spawn a different program specific to your runtime.
+  const child = spawn('my-runtime-dev-server', [options.entrypoint], {
+    stdio: ['ignore', 'inherit', 'inherit', 'pipe'],
+  });
+
+  // In this example, the child process will write the port number to FD 3…
+  const portPipe = child.stdio[3];
+  const childPort = await new Promise(resolve => {
+    portPipe.setEncoding('utf8');
+    portPipe.once('data', data => {
+      resolve(Number(data));
+    });
+  });
+
+  return { pid: child.pid, port: childPort };
 }
 ```
 
-If this method is not defined, Vercel CLI will default to [this function](https://github.com/vercel/vercel/blob/52994bfe26c5f4f179bdb49783ee57ce19334631/packages/now-build-utils/src/should-serve.ts).
-
-### Runtime Options
-
-The exported functions [`analyze`](#analyze), [`build`](#build), and [`prepareCache`](#preparecache) receive one argument with the following properties.
-
-**Properties:**
-
-- `files`: All source files of the project as a [Files](#files) data structure.
-- `entrypoint`: Name of entrypoint file for this particular build job. Value `files[entrypoint]` is guaranteed to exist and be a valid [File](#files) reference. `entrypoint` is always a discrete file and never a glob, since globs are expanded into separate builds at deployment time.
-- `workPath`: A writable temporary directory where you are encouraged to perform your build process. This directory will be populated with the restored cache from the previous run (if any) for [`analyze`](#analyze) and [`build`](#build).
-- `cachePath`: A writable temporary directory where you can build a cache for the next run. This is only passed to `prepareCache`.
-- `config`: An arbitrary object passed from by the user in the [Build definition](#defining-the-build-step) in `vercel.json`.
-
-## Examples
-
-Check out our [Node.js Runtime](https://github.com/vercel/vercel/tree/master/packages/now-node), [Go Runtime](https://github.com/vercel/vercel/tree/master/packages/now-go), [Python Runtime](https://github.com/vercel/vercel/tree/master/packages/now-python) or [Ruby Runtime](https://github.com/vercel/vercel/tree/master/packages/now-ruby) for examples of how to build one.
-
-## Technical Details
-
 ### Execution Context
 
-A [Serverless Function](https://vercel.com/docs/v2/serverless-functions/introduction) is created where the Runtime logic is executed. The lambda is run using the Node.js 8 runtime. A brand new sandbox is created for each deployment, for security reasons. The sandbox is cleaned up between executions to ensure no lingering temporary files are shared from build to build.
+- Runtimes are executed in a Linux container that closely matches the Servereless Function runtime environment.
+- The Runtime code is executed using Node.js version **12.x**.
+- A brand new sandbox is created for each deployment, for security reasons.
+- The sandbox is cleaned up between executions to ensure no lingering temporary files are shared from build to build.
 
-All the APIs you export ([`analyze`](#analyze), [`build`](#build) and [`prepareCache`](#preparecache)) are not guaranteed to be run in the same process, but the filesystem we expose (e.g.: `workPath` and the results of calling [`getWriteableDirectory`](#getWriteableDirectory) ) is retained.
+All the APIs you export ([`analyze()`](#analyze), [`build()`](#build),
+[`prepareCache()`](#preparecache), etc.) are not guaranteed to be run in the
+same process, but the filesystem we expose (e.g.: `workPath` and the results
+of calling [`getWritableDirectory`](#getWritableDirectory) ) is retained.
 
 If you need to share state between those steps, use the filesystem.
 
@@ -173,11 +220,11 @@ The env and secrets specified by the user as `build.env` are passed to the Runti
 
 When you publish your Runtime to npm, make sure to not specify `@vercel/build-utils` (as seen below in the API definitions) as a dependency, but rather as part of `peerDependencies`.
 
-## Types
+## `@vercel/build-utils` Types
 
 ### `Files`
 
-```ts
+```typescript
 import { File } from '@vercel/build-utils';
 type Files = { [filePath: string]: File };
 ```
@@ -188,7 +235,7 @@ When used as an input, the `Files` object will only contain `FileRefs`. When `Fi
 
 An example of a valid output `Files` object is:
 
-```json
+```javascript
 {
   "index.html": FileRef,
   "api/index.js": Lambda
@@ -199,7 +246,7 @@ An example of a valid output `Files` object is:
 
 This is an abstract type that can be imported if you are using TypeScript.
 
-```ts
+```typescript
 import { File } from '@vercel/build-utils';
 ```
 
@@ -211,71 +258,71 @@ Valid `File` types include:
 
 ### `FileRef`
 
-```ts
+```typescript
 import { FileRef } from '@vercel/build-utils';
 ```
 
-This is a [JavaScript class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract file instance stored in our platform, based on the file identifier string (its checksum). When a `Files` object is passed as an input to `analyze` or `build`, all its values will be instances of `FileRef`.
+This is a [class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract file instance stored in our platform, based on the file identifier string (its checksum). When a `Files` object is passed as an input to `analyze` or `build`, all its values will be instances of `FileRef`.
 
 **Properties:**
 
-- `mode : Number` file mode
-- `digest : String` a checksum that represents the file
+- `mode: Number` file mode
+- `digest: String` a checksum that represents the file
 
 **Methods:**
 
-- `toStream() : Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
+- `toStream(): Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
 
 ### `FileFsRef`
 
-```ts
+```typescript
 import { FileFsRef } from '@vercel/build-utils';
 ```
 
-This is a [JavaScript class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract instance of a file present in the filesystem that the build process is executing in.
+This is a [class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract instance of a file present in the filesystem that the build process is executing in.
 
 **Properties:**
 
-- `mode : Number` file mode
-- `fsPath : String` the absolute path of the file in file system
+- `mode: Number` file mode
+- `fsPath: String` the absolute path of the file in file system
 
 **Methods:**
 
-- `static async fromStream({ mode : Number, stream : Stream, fsPath : String }) : FileFsRef` creates an instance of a [FileFsRef](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) from `Stream`, placing file at `fsPath` with `mode`
-- `toStream() : Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
+- `static async fromStream({ mode: Number, stream: Stream, fsPath: String }): FileFsRef` creates an instance of a [FileFsRef](#FileFsRef) from `Stream`, placing file at `fsPath` with `mode`
+- `toStream(): Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
 
 ### `FileBlob`
 
-```ts
+```typescript
 import { FileBlob } from '@vercel/build-utils';
 ```
 
-This is a [JavaScript class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract instance of a file present in memory.
+This is a [class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents an abstract instance of a file present in memory.
 
 **Properties:**
 
-- `mode : Number` file mode
-- `data : String | Buffer` the body of the file
+- `mode: Number` file mode
+- `data: String | Buffer` the body of the file
 
 **Methods:**
 
-- `static async fromStream({ mode : Number, stream : Stream }) :FileBlob` creates an instance of a [FileBlob](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) from [`Stream`](https://nodejs.org/api/stream.html) with `mode`
-- `toStream() : Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
+- `static async fromStream({ mode: Number, stream: Stream }): FileBlob` creates an instance of a [FileBlob](#FileBlob) from [`Stream`](https://nodejs.org/api/stream.html) with `mode`
+- `toStream(): Stream` creates a [Stream](https://nodejs.org/api/stream.html) of the file body
 
 ### `Lambda`
 
-```ts
+```typescript
 import { Lambda } from '@vercel/build-utils';
 ```
 
-This is a [JavaScript class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes), called a Serverless Function, that can be created by supplying `files`, `handler`, `runtime`, and `environment` as an object to the [`createLambda`](#createlambda) helper. The instances of this class should not be created directly. Instead, invoke the [`createLambda`](#createlambda) helper function.
+This is a [class](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) that represents a Serverless Function. An instance can be created by supplying `files`, `handler`, `runtime`, and `environment` as an object to the [`createLambda`](#createlambda) helper. The instances of this class should not be created directly. Instead, invoke the [`createLambda`](#createlambda) helper function.
 
 **Properties:**
 
-- `files : Files` the internal filesystem of the lambda
-- `handler : String` path to handler file and (optionally) a function name it exports
-- `runtime : LambdaRuntime` the name of the lambda runtime
-- `environment : Object` key-value map of handler-related (aside of those passed by user) environment variables
+- `files: Files` the internal filesystem of the lambda
+- `handler: String` path to handler file and (optionally) a function name it exports
+- `runtime: LambdaRuntime` the name of the lambda runtime
+- `environment: Object` key-value map of handler-related (aside of those passed by user) environment variables
 
 ### `LambdaRuntime`
 
@@ -291,15 +338,15 @@ This is an abstract enumeration type that is implemented by one of the following
 - `ruby2.5`
 - `provided`
 
-## JavaScript API
+## `@vercel/build-utils` Helper Functions
 
 The following is exposed by `@vercel/build-utils` to simplify the process of writing Runtimes, manipulating the file system, using the above types, etc.
 
-### `createLambda`
+### `createLambda()`
 
-Signature: `createLambda(Object spec) : Lambda`
+Signature: `createLambda(Object spec): Lambda`
 
-```ts
+```typescript
 import { createLambda } from '@vercel/build-utils';
 ```
 
@@ -316,29 +363,33 @@ await createLambda({
 });
 ```
 
-### `download`
+### `download()`
 
-Signature: `download() : Files`
+Signature: `download(): Files`
 
-```ts
+```typescript
 import { download } from '@vercel/build-utils';
 ```
 
-This utility allows you to download the contents of a [`Files`](#files) data structure, therefore creating the filesystem represented in it.
+This utility allows you to download the contents of a [`Files`](#files) data
+structure, therefore creating the filesystem represented in it.
 
-Since `Files` is an abstract way of representing files, you can think of `download` as a way of making that virtual filesystem _real_.
+Since `Files` is an abstract way of representing files, you can think of
+`download()` as a way of making that virtual filesystem _real_.
 
-If the **optional** `meta` property is passed (the argument for [build](#build)), only the files that have changed are downloaded. This is decided using `filesRemoved` and `filesChanged` inside that object.
+If the **optional** `meta` property is passed (the argument for
+[`build()`](#build)), only the files that have changed are downloaded.
+This is decided using `filesRemoved` and `filesChanged` inside that object.
 
 ```js
 await download(files, workPath, meta);
 ```
 
-### `glob`
+### `glob()`
 
-Signature: `glob() : Files`
+Signature: `glob(): Files`
 
-```ts
+```typescript
 import { glob } from '@vercel/build-utils';
 ```
 
@@ -355,21 +406,21 @@ exports.build = ({ files, workPath }) => {
 }
 ```
 
-### `getWriteableDirectory`
+### `getWritableDirectory()`
 
-Signature: `getWriteableDirectory() : String`
+Signature: `getWritableDirectory(): String`
 
-```ts
-import { getWriteableDirectory } from '@vercel/build-utils';
+```typescript
+import { getWritableDirectory } from '@vercel/build-utils';
 ```
 
 In some occasions, you might want to write to a temporary directory.
 
-### `rename`
+### `rename()`
 
-Signature: `rename(Files) : Files`
+Signature: `rename(Files, Function): Files`
 
-```ts
+```typescript
 import { rename } from '@vercel/build-utils';
 ```
 

package.json

@@ -20,6 +20,7 @@
     "@zeit/ncc": "0.20.4",
     "async-retry": "1.2.3",
     "buffer-replace": "1.0.0",
+    "cheerio": "1.0.0-rc.3",
     "eslint": "6.2.2",
     "eslint-config-prettier": "6.1.0",
     "eslint-plugin-jest": "23.8.2",

packages/frameworks/frameworks.json

@@ -640,7 +640,7 @@
     },
     "settings": {
       "buildCommand": {
-        "placeholder": "`npm run build` or `nuxt build`"
+        "placeholder": "`npm run build` or `nuxt generate`"
       },
       "devCommand": {
         "value": "nuxt"

packages/frameworks/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/frameworks",
-  "version": "0.0.15-canary.4",
+  "version": "0.0.16-canary.0",
   "main": "frameworks.json",
   "license": "UNLICENSED",
   "scripts": {
@@ -9,7 +9,7 @@
   "devDependencies": {
     "@types/jest": "24.0.22",
     "@types/node": "12.0.4",
-    "ajv": "6.10.2",
+    "ajv": "6.12.2",
     "jest": "24.9.0",
     "ts-jest": "24.1.0",
     "typescript": "3.9.3"

packages/now-build-utils/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/build-utils",
-  "version": "2.3.2-canary.5",
+  "version": "2.4.1-canary.1",
   "license": "MIT",
   "main": "./dist/index.js",
   "types": "./dist/index.d.js",

packages/now-build-utils/src/errors.ts

@@ -38,3 +38,78 @@ interface Props {
    */
   action?: string;
 }
+
+export function getPrettyError(obj: {
+  dataPath?: string;
+  message?: string;
+  params: any;
+}): NowBuildError {
+  const docsUrl = 'https://vercel.com/docs/configuration';
+  try {
+    const { dataPath, params, message: ajvMessage } = obj;
+    const prop = getTopLevelPropertyName(dataPath);
+    let message =
+      dataPath && dataPath.startsWith('.') ? `\`${dataPath.slice(1)}\` ` : '';
+
+    if (params && typeof params.additionalProperty === 'string') {
+      const suggestion = getSuggestion(prop, params.additionalProperty);
+      message += `should NOT have additional property \`${params.additionalProperty}\`. ${suggestion}`;
+    } else if (params && typeof params.missingProperty === 'string') {
+      message += `missing required property \`${params.missingProperty}\`.`;
+    } else {
+      message += `${ajvMessage}.`;
+    }
+
+    return new NowBuildError({
+      code: 'DEV_VALIDATE_CONFIG',
+      message: message,
+      link: prop ? `${docsUrl}#project/${prop.toLowerCase()}` : docsUrl,
+      action: 'View Documentation',
+    });
+  } catch (e) {
+    return new NowBuildError({
+      code: 'DEV_VALIDATE_CONFIG',
+      message: `Failed to validate configuration.`,
+      link: docsUrl,
+      action: 'View Documentation',
+    });
+  }
+}
+
+/**
+ * Get the top level property from the dataPath.
+ * `.cleanUrls` => `cleanUrls`
+ * `.headers[0].source` => `headers`
+ * `.headers[0].headers[0]` => `headers`
+ * `` => ``
+ */
+function getTopLevelPropertyName(dataPath?: string): string {
+  if (dataPath && dataPath.startsWith('.')) {
+    const lastIndex = dataPath.indexOf('[');
+    return lastIndex > -1 ? dataPath.slice(1, lastIndex) : dataPath.slice(1);
+  }
+  return '';
+}
+
+const mapTypoToSuggestion: { [key: string]: { [key: string]: string } } = {
+  '': {
+    builder: 'builds',
+    'build.env': '{ "build": { "env": {"name": "value"} } }',
+    'builds.env': '{ "build": { "env": {"name": "value"} } }',
+  },
+  rewrites: { src: 'source', dest: 'destination' },
+  redirects: { src: 'source', dest: 'destination', status: 'statusCode' },
+  headers: { src: 'source', header: 'headers' },
+  routes: {
+    source: 'src',
+    destination: 'dest',
+    header: 'headers',
+    method: 'methods',
+  },
+};
+
+function getSuggestion(topLevelProp: string, additionalProperty: string) {
+  const choices = mapTypoToSuggestion[topLevelProp];
+  const choice = choices ? choices[additionalProperty] : undefined;
+  return choice ? `Did you mean \`${choice}\`?` : 'Please remove it.';
+}

packages/now-build-utils/src/index.ts

@@ -27,6 +27,7 @@ import {
   getLatestNodeVersion,
   getDiscontinuedNodeVersions,
 } from './fs/node-version';
+import { NowBuildError } from './errors';
 import streamToBuffer from './fs/stream-to-buffer';
 import shouldServe from './should-serve';
 import debug from './debug';
@@ -111,9 +112,11 @@ export const getPlatformEnv = (name: string): string | undefined => {
   const n = process.env[nName];
   if (typeof v === 'string') {
     if (typeof n === 'string') {
-      throw new Error(
-        `Both "${vName}" and "${nName}" env vars are defined. Please only define the "${vName}" env var`
-      );
+      throw new NowBuildError({
+        code: 'CONFLICTING_ENV_VAR_NAMES',
+        message: `Both "${vName}" and "${nName}" env vars are defined. Please only define the "${vName}" env var.`,
+        link: 'https://vercel.link/combining-old-and-new-config',
+      });
     }
     return v;
   }

packages/now-build-utils/test/unit.builds-and-routes-detector.test.ts

@@ -493,7 +493,7 @@ describe('Test `detectBuilders`', () => {
   });
 
   it('use a custom runtime', async () => {
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
     const { builders, errors } = await detectBuilders(files, null, {
       functions,
@@ -501,11 +501,11 @@ describe('Test `detectBuilders`', () => {
 
     expect(errors).toBe(null);
     expect(builders!.length).toBe(1);
-    expect(builders![0].use).toBe('now-php@0.0.8');
+    expect(builders![0].use).toBe('vercel-php@0.1.0');
   });
 
   it('use a custom runtime but without a source', async () => {
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/team.js'];
     const { errors } = await detectBuilders(files, null, {
       functions,
@@ -1538,7 +1538,7 @@ describe('Test `detectBuilders` with `featHandleMiss=true`', () => {
   });
 
   it('use a custom runtime', async () => {
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
     const { builders, errors } = await detectBuilders(files, null, {
       functions,
@@ -1547,11 +1547,11 @@ describe('Test `detectBuilders` with `featHandleMiss=true`', () => {
 
     expect(errors).toBe(null);
     expect(builders!.length).toBe(1);
-    expect(builders![0].use).toBe('now-php@0.0.8');
+    expect(builders![0].use).toBe('vercel-php@0.1.0');
   });
 
   it('use a custom runtime but without a source', async () => {
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/team.js'];
     const { errors } = await detectBuilders(files, null, {
       functions,
@@ -2081,7 +2081,7 @@ it('Test `detectRoutes`', async () => {
 
   {
     // use a custom runtime
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
 
     const { defaultRoutes } = await detectBuilders(files, null, { functions });
@@ -2393,7 +2393,7 @@ it('Test `detectRoutes` with `featHandleMiss=true`', async () => {
 
   {
     // use a custom runtime
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
 
     const { defaultRoutes, rewriteRoutes } = await detectBuilders(files, null, {
@@ -2692,7 +2692,7 @@ it('Test `detectRoutes` with `featHandleMiss=true`, `cleanUrls=true`', async ()
 
   {
     // use a custom runtime
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
 
     const {
@@ -2941,7 +2941,7 @@ it('Test `detectRoutes` with `featHandleMiss=true`, `cleanUrls=true`, `trailingS
 
   {
     // use a custom runtime
-    const functions = { 'api/user.php': { runtime: 'now-php@0.0.8' } };
+    const functions = { 'api/user.php': { runtime: 'vercel-php@0.1.0' } };
     const files = ['api/user.php'];
 
     const {

packages/now-build-utils/test/unit.get-platform-env.test.ts

@@ -39,7 +39,7 @@ describe('Test `getPlatformEnv()`', () => {
     assert(err);
     assert.equal(
       err!.message,
-      'Both "VERCEL_FOO" and "NOW_FOO" env vars are defined. Please only define the "VERCEL_FOO" env var'
+      'Both "VERCEL_FOO" and "NOW_FOO" env vars are defined. Please only define the "VERCEL_FOO" env var.'
     );
   });
 });

packages/now-cgi/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/cgi",
-  "version": "1.0.6-canary.0",
+  "version": "1.0.6",
   "license": "MIT",
   "repository": {
     "type": "git",

packages/now-cli/package.json

@@ -1,9 +1,9 @@
 {
   "name": "vercel",
-  "version": "19.0.2-canary.15",
+  "version": "19.1.2-canary.14",
   "preferGlobal": true,
   "license": "Apache-2.0",
-  "description": "The command-line interface for Now",
+  "description": "The command-line interface for Vercel",
   "homepage": "https://vercel.com",
   "repository": {
     "type": "git",
@@ -12,7 +12,7 @@
   },
   "scripts": {
     "preinstall": "node ./scripts/preinstall.js",
-    "test-unit": "nyc ava test/unit.js test/dev-builder.unit.js test/dev-router.unit.js test/dev-server.unit.js --serial --fail-fast --verbose",
+    "test-unit": "nyc ava test/unit.js test/dev-builder.unit.js test/dev-router.unit.js test/dev-server.unit.js test/dev-validate.unit.js --serial --fail-fast --verbose",
     "test-integration-cli": "ava test/integration.js --serial --fail-fast --verbose",
     "test-integration-v1": "ava test/integration-v1.js --serial --fail-fast",
     "test-integration-dev": "ava test/dev/integration.js --serial --fail-fast --verbose",
@@ -62,13 +62,13 @@
     "node": ">= 10"
   },
   "dependencies": {
-    "@vercel/build-utils": "2.3.2-canary.5",
-    "@vercel/go": "1.1.2-canary.2",
-    "@vercel/next": "2.6.3-canary.6",
-    "@vercel/node": "1.6.2-canary.5",
-    "@vercel/python": "1.2.2-canary.2",
-    "@vercel/ruby": "1.2.2-canary.1",
-    "@vercel/static-build": "0.17.2-canary.1"
+    "@vercel/build-utils": "2.4.1-canary.1",
+    "@vercel/go": "1.1.3-canary.1",
+    "@vercel/next": "2.6.8-canary.4",
+    "@vercel/node": "1.7.2-canary.1",
+    "@vercel/python": "1.2.2",
+    "@vercel/ruby": "1.2.3-canary.0",
+    "@vercel/static-build": "0.17.4-canary.1"
   },
   "devDependencies": {
     "@sentry/node": "5.5.0",
@@ -106,7 +106,7 @@
     "@zeit/fun": "0.11.2",
     "@zeit/ncc": "0.18.5",
     "@zeit/source-map-support": "0.6.2",
-    "ajv": "6.10.2",
+    "ajv": "6.12.2",
     "alpha-sort": "2.0.1",
     "ansi-escapes": "3.0.0",
     "ansi-regex": "3.0.0",
@@ -136,6 +136,7 @@
     "escape-html": "1.0.3",
     "esm": "3.1.4",
     "execa": "3.2.0",
+    "fast-deep-equal": "3.1.3",
     "fs-extra": "7.0.1",
     "get-port": "5.1.1",
     "glob": "7.1.2",

packages/now-cli/src/commands/deploy/latest.js

@@ -3,8 +3,8 @@ import bytes from 'bytes';
 import { join } from 'path';
 import { write as copy } from 'clipboardy';
 import chalk from 'chalk';
-import title from 'title';
 import { fileNameSymbol } from '@vercel/client';
+import { getPrettyError } from '@vercel/build-utils';
 import Client from '../../util/client';
 import { handleError } from '../../util/error';
 import getArgs from '../../util/get-args';
@@ -39,7 +39,6 @@ import {
 } from '../../util/errors-ts';
 import { SchemaValidationFailed } from '../../util/errors';
 import purchaseDomainIfAvailable from '../../util/domains/purchase-domain-if-available';
-import isWildcardAlias from '../../util/alias/is-wildcard-alias';
 import confirm from '../../util/input/confirm';
 import editProjectSettings from '../../util/input/edit-project-settings';
 import {
@@ -56,6 +55,7 @@ import validatePaths, {
 } from '../../util/validate-paths';
 import { readLocalConfig } from '../../util/config/files';
 import { getCommandName } from '../../util/pkg-name.ts';
+import { getPreferredPreviewURL } from '../../util/deploy/get-preferred-preview-url.ts';
 
 const addProcessEnv = async (log, env) => {
   let val;
@@ -87,6 +87,7 @@ const addProcessEnv = async (log, env) => {
 
 const printDeploymentStatus = async (
   output,
+  client,
   {
     readyState,
     alias: aliasList,
@@ -119,18 +120,14 @@ const printDeploymentStatus = async (
     let previewUrl;
     let isWildcard;
     if (!isFile && Array.isArray(aliasList) && aliasList.length > 0) {
-      // search for a non now.sh/non wildcard domain
-      // but fallback to the first alias in the list
-      const mainAlias =
-        aliasList.find(
-          alias =>
-            !alias.endsWith('.now.sh') &&
-            !alias.endsWith('.vercel.app') &&
-            !isWildcardAlias(alias)
-        ) || aliasList[0];
-
-      isWildcard = isWildcardAlias(mainAlias);
-      previewUrl = isWildcard ? mainAlias : `https://${mainAlias}`;
+      const previewUrlInfo = await getPreferredPreviewURL(client, aliasList);
+      if (previewUrlInfo) {
+        isWildcard = previewUrlInfo.isWildcard;
+        previewUrl = previewUrlInfo.previewUrl;
+      } else {
+        isWildcard = false;
+        previewUrl = `https://${deploymentUrl}`;
+      }
     } else {
       // fallback to deployment url
       isWildcard = false;
@@ -706,6 +703,12 @@ export default async function main(
 
   return printDeploymentStatus(
     output,
+    new Client({
+      apiUrl: ctx.apiUrl,
+      token: ctx.authConfig.token,
+      currentTeam: org.type === 'team' ? org.id : null,
+      debug: debugEnabled,
+    }),
     deployment,
     deployStamp,
     !argv['--no-clipboard'],
@@ -735,53 +738,10 @@ function handleCreateDeployError(output, error, localConfig) {
     return 1;
   }
   if (error instanceof SchemaValidationFailed) {
-    const { message, params, keyword, dataPath } = error.meta;
-
-    if (params && params.additionalProperty) {
-      const prop = params.additionalProperty;
-
-      output.error(
-        `The property ${code(prop)} is not allowed in ${highlight(
-          localConfig[fileNameSymbol]
-        )} – please remove it.`
-      );
-
-      if (prop === 'build.env' || prop === 'builds.env') {
-        output.note(
-          `Do you mean ${code('build')} (object) with a property ${code(
-            'env'
-          )} (object) instead of ${code(prop)}?`
-        );
-      }
-
-      return 1;
-    }
-
-    if (dataPath === '.name') {
-      output.error(message);
-      return 1;
-    }
-
-    if (keyword === 'type') {
-      const prop = dataPath.substr(1, dataPath.length);
-
-      output.error(
-        `The property ${code(prop)} in ${highlight(
-          localConfig[fileNameSymbol]
-        )} can only be of type ${code(title(params.type))}.`
-      );
-
-      return 1;
-    }
-
-    const link = 'https://vercel.com/docs/configuration';
-
-    output.error(
-      `Failed to validate ${highlight(
-        localConfig[fileNameSymbol]
-      )}: ${message}\nDocumentation: ${link}`
-    );
-
+    const niceError = getPrettyError(error.meta);
+    const fileName = localConfig[fileNameSymbol] || 'vercel.json';
+    niceError.message = `Invalid ${fileName} - ${niceError.message}`;
+    output.prettyError(niceError);
     return 1;
   }
   if (error instanceof TooManyRequests) {

packages/now-cli/src/commands/dev/dev.ts

@@ -9,6 +9,7 @@ import { getLinkedProject } from '../../util/projects/link';
 import { getFrameworks } from '../../util/get-frameworks';
 import { isSettingValue } from '../../util/is-setting-value';
 import { getCommandName } from '../../util/pkg-name';
+import { ProjectSettings } from '../../types';
 
 type Options = {
   '--debug'?: boolean;
@@ -50,21 +51,26 @@ export default async function dev(
     return 1;
   }
 
-  let devCommand: undefined | string;
-  let frameworkSlug: null | string = null;
+  let devCommand: string | undefined;
+  let frameworkSlug: string | undefined;
+  let projectSettings: ProjectSettings | undefined;
   if (link.status === 'linked') {
     const { project, org } = link;
     client.currentTeam = org.type === 'team' ? org.id : undefined;
 
+    projectSettings = project;
+
     if (project.devCommand) {
       devCommand = project.devCommand;
     } else if (project.framework) {
       const framework = frameworks.find(f => f.slug === project.framework);
 
       if (framework) {
-        frameworkSlug = framework.slug;
-        const defaults = framework.settings.devCommand;
+        if (framework.slug) {
+          frameworkSlug = framework.slug;
+        }
 
+        const defaults = framework.settings.devCommand;
         if (isSettingValue(defaults)) {
           devCommand = defaults.value;
         }
@@ -81,6 +87,7 @@ export default async function dev(
     debug,
     devCommand,
     frameworkSlug,
+    projectSettings,
   });
 
   process.once('SIGINT', () => devServer.stop());

packages/now-cli/src/commands/dev/index.ts

@@ -10,6 +10,7 @@ import handleError from '../../util/handle-error';
 import createOutput from '../../util/output/create-output';
 import logo from '../../util/output/logo';
 import cmd from '../../util/output/cmd';
+import highlight from '../../util/output/highlight';
 import dev from './dev';
 import readPackage from '../../util/read-package';
 import readConfig from '../../util/config/read-config';
@@ -119,6 +120,21 @@ export default async function main(ctx: NowContext) {
   try {
     return await dev(ctx, argv, args, output);
   } catch (err) {
+    if (err.code === 'ENOTFOUND') {
+      // Error message will look like the following:
+      // "request to https://api.vercel.com/www/user failed, reason: getaddrinfo ENOTFOUND api.vercel.com"
+      const matches = /getaddrinfo ENOTFOUND (.*)$/.exec(err.message || '');
+      if (matches && matches[1]) {
+        const hostname = matches[1];
+        output.error(
+          `The hostname ${highlight(
+            hostname
+          )} could not be resolved. Please verify your internet connectivity and DNS configuration.`
+        );
+      }
+      output.debug(err.stack);
+      return 1;
+    }
     output.prettyError(err);
     output.debug(stringifyError(err));
     return 1;

packages/now-cli/src/commands/env/pull.ts

@@ -9,16 +9,39 @@ import getDecryptedSecret from '../../util/env/get-decrypted-secret';
 import param from '../../util/output/param';
 import withSpinner from '../../util/with-spinner';
 import { join } from 'path';
-import { promises, existsSync } from 'fs';
+import { promises, openSync, closeSync, readSync } from 'fs';
 import { emoji, prependEmoji } from '../../util/emoji';
 import { getCommandName } from '../../util/pkg-name';
 const { writeFile } = promises;
 
+const CONTENTS_PREFIX = '# Created by Vercel CLI\n';
+
 type Options = {
   '--debug': boolean;
   '--yes': boolean;
 };
 
+function readHeadSync(path: string, length: number) {
+  const buffer = Buffer.alloc(length);
+  const fd = openSync(path, 'r');
+  try {
+    readSync(fd, buffer, 0, buffer.length, null);
+  } finally {
+    closeSync(fd);
+  }
+  return buffer.toString();
+}
+
+function tryReadHeadSync(path: string, length: number) {
+  try {
+    return readHeadSync(path, length);
+  } catch (err) {
+    if (err.code !== 'ENOENT') {
+      throw err;
+    }
+  }
+}
+
 export default async function pull(
   client: Client,
   project: Project,
@@ -35,10 +58,14 @@ export default async function pull(
 
   const [filename = '.env'] = args;
   const fullPath = join(process.cwd(), filename);
-  const exists = existsSync(fullPath);
   const skipConfirmation = opts['--yes'];
 
-  if (
+  const head = tryReadHeadSync(fullPath, Buffer.byteLength(CONTENTS_PREFIX));
+  const exists = typeof head !== 'undefined';
+
+  if (head === CONTENTS_PREFIX) {
+    output.print(`Overwriting existing ${chalk.bold(filename)} file\n`);
+  } else if (
     exists &&
     !skipConfirmation &&
     !(await promptBool(
@@ -83,6 +110,7 @@ export default async function pull(
   });
 
   const contents =
+    CONTENTS_PREFIX +
     records
       .filter(obj => {
         if (!obj.found) {
@@ -95,7 +123,8 @@ export default async function pull(
         return true;
       })
       .map(({ key, value }) => `${key}="${escapeValue(value)}"`)
-      .join('\n') + '\n';
+      .join('\n') +
+    '\n';
 
   await writeFile(fullPath, contents, 'utf8');
 

packages/now-cli/src/index.js

@@ -24,6 +24,7 @@ import checkForUpdate from 'update-check';
 import ms from 'ms';
 import { URL } from 'url';
 import * as Sentry from '@sentry/node';
+import { NowBuildError } from '@vercel/build-utils';
 import getGlobalPathConfig from './util/config/global-path';
 import {
   getDefaultConfig,
@@ -114,10 +115,10 @@ const main = async argv_ => {
   }
 
   if (
-    localConfig instanceof NowError &&
+    (localConfig instanceof NowError || localConfig instanceof NowBuildError) &&
     !(localConfig instanceof ERRORS.CantFindConfig)
   ) {
-    output.error(`Failed to load local config file: ${localConfig.message}`);
+    output.prettyError(localConfig);
     return 1;
   }
 
@@ -313,21 +314,6 @@ const main = async argv_ => {
     // need to migrate.
     if (authConfig.credentials) {
       authConfigExists = false;
-    } else if (
-      !authConfig.token &&
-      !subcommandsWithoutToken.includes(targetOrSubcommand) &&
-      !argv['--help'] &&
-      !argv['--token']
-    ) {
-      console.error(
-        error(
-          `The content of "${hp(VERCEL_AUTH_CONFIG_PATH)}" is invalid. ` +
-            `No \`token\` property found inside. Run ${getCommandName(
-              'login'
-            )} to authorize.`
-        )
-      );
-      return 1;
     }
   } else {
     const results = await getDefaultAuthConfig(authConfig);
@@ -637,34 +623,19 @@ const main = async argv_ => {
         .send();
     }
   } catch (err) {
-    if (err.code === 'ENOTFOUND' && err.hostname === 'api.vercel.com') {
-      output.error(
-        `The hostname ${highlight(
-          'api.vercel.com'
-        )} could not be resolved. Please verify your internet connectivity and DNS configuration.`
-      );
-      output.debug(err.stack);
-
-      return 1;
-    }
-
-    await reportError(Sentry, err, apiUrl, configFiles);
-
-    // If there is a code we should not consider the error unexpected
-    // but instead show the message. Any error that is handled by this should
-    // actually be handled in the sub command instead. Please make sure
-    // that happens for anything that lands here. It should NOT bubble up to here.
-    if (err.code) {
-      output.debug(err.stack);
-      output.error(err.message);
-
-      if (shouldCollectMetrics) {
-        metric
-          .event(eventCategory, '1', pkg.version)
-          .exception(err.message)
-          .send();
+    if (err.code === 'ENOTFOUND') {
+      // Error message will look like the following:
+      // "request to https://api.vercel.com/www/user failed, reason: getaddrinfo ENOTFOUND api.vercel.com"
+      const matches = /getaddrinfo ENOTFOUND (.*)$/.exec(err.message || '');
+      if (matches && matches[1]) {
+        const hostname = matches[1];
+        output.error(
+          `The hostname ${highlight(
+            hostname
+          )} could not be resolved. Please verify your internet connectivity and DNS configuration.`
+        );
       }
-
+      output.debug(err.stack);
       return 1;
     }
 
@@ -675,9 +646,23 @@ const main = async argv_ => {
         .send();
     }
 
-    // Otherwise it is an unexpected error and we should show the trace
-    // and an unexpected error message
-    output.error(`An unexpected error occurred in ${subcommand}: ${err.stack}`);
+    // If there is a code we should not consider the error unexpected
+    // but instead show the message. Any error that is handled by this should
+    // actually be handled in the sub command instead. Please make sure
+    // that happens for anything that lands here. It should NOT bubble up to here.
+    if (err.code) {
+      output.debug(err.stack);
+      output.prettyError(err);
+    } else {
+      await reportError(Sentry, err, apiUrl, configFiles);
+
+      // Otherwise it is an unexpected error and we should show the trace
+      // and an unexpected error message
+      output.error(
+        `An unexpected error occurred in ${subcommand}: ${err.stack}`
+      );
+    }
+
     return 1;
   }
 
@@ -688,8 +673,6 @@ const main = async argv_ => {
   return exitCode;
 };
 
-debug('start');
-
 const handleRejection = async err => {
   debug('handling rejection');
 

packages/now-cli/src/types.ts

@@ -244,15 +244,20 @@ export interface ProjectEnvVariable {
   system?: boolean;
 }
 
-export interface Project {
+export interface ProjectSettings {
+  framework?: string | null;
+  devCommand?: string | null;
+  buildCommand?: string | null;
+  outputDirectory?: string | null;
+  rootDirectory?: string | null;
+}
+
+export interface Project extends ProjectSettings {
   id: string;
   name: string;
   accountId: string;
   updatedAt: number;
   createdAt: number;
-  devCommand?: string | null;
-  framework?: string | null;
-  rootDirectory?: string | null;
   latestDeployments?: Partial<Deployment>[];
 }
 

packages/now-cli/src/util/certs/get-certs-for-cn.ts

@@ -0,0 +1,17 @@
+import { stringify } from 'querystring';
+import { Cert } from '../../types';
+import Client from '../client';
+
+/**
+ * Returns certs that contain @param cn.
+ */
+export async function getCertsForCn(
+  client: Client,
+  cn: string,
+  { limit }: { limit?: number } = {}
+) {
+  const { certs } = await client.fetch<{
+    certs: Cert[];
+  }>(`/v4/now/certs?${stringify({ cn, ...(limit ? { limit } : {}) })}`);
+  return certs;
+}

packages/now-cli/src/util/client.ts

@@ -24,7 +24,7 @@ export default class Client extends EventEmitter {
   _withCache: boolean;
   _output: Output;
   _token: string;
-  currentTeam?: string;
+  currentTeam?: string | null;
 
   constructor({
     apiUrl,
@@ -36,7 +36,7 @@ export default class Client extends EventEmitter {
   }: {
     apiUrl: string;
     token: string;
-    currentTeam?: string;
+    currentTeam?: string | null;
     forceNew?: boolean;
     withCache?: boolean;
     debug?: boolean;

packages/now-cli/src/util/deploy/get-preferred-preview-url.ts

@@ -0,0 +1,48 @@
+import isWildcardAlias from '../alias/is-wildcard-alias';
+import { getCertsForCn } from '../certs/get-certs-for-cn';
+import Client from '../client';
+
+/**
+ * Tries to find the "best" alias url.
+ * @param aliasList
+ */
+export async function getPreferredPreviewURL(
+  client: Client,
+  aliasList: string[]
+) {
+  if (aliasList.length === 0) {
+    return null;
+  }
+
+  /**
+   * First checks for non public aliases and non wildcard domains.
+   */
+  const preferredAliases = aliasList.filter(
+    alias =>
+      !alias.endsWith('.now.sh') &&
+      !alias.endsWith('.vercel.app') &&
+      !isWildcardAlias(alias)
+  );
+  for (const alias of preferredAliases) {
+    const certs = await getCertsForCn(client, alias, { limit: 1 }).catch(() => {
+      return null;
+    });
+    if (certs && certs.length > 0) {
+      return { previewUrl: `https://${alias}`, isWildcard: false };
+    }
+  }
+
+  /**
+   * Fallback to first alias
+   */
+  const [firstAlias] = aliasList;
+  if (isWildcardAlias(firstAlias)) {
+    return { previewUrl: firstAlias, isWildcard: true };
+  }
+
+  if (firstAlias.endsWith('.vercel.app') || firstAlias.endsWith('.now.sh')) {
+    return { previewUrl: `https://${firstAlias}`, isWildcard: false };
+  }
+
+  return { previewUrl: `http://${firstAlias}`, isWildcard: false };
+}

packages/now-cli/src/util/dev/builder-cache.ts

@@ -264,7 +264,7 @@ async function npmInstall(
             ? '`npm` is not installed'
             : 'Failed to install `vercel dev` dependencies',
         code: 'NPM_INSTALL_ERROR',
-        link: 'https://vercel.link/npm-install-error',
+        link: 'https://vercel.link/npm-install-failed-dev',
       });
     }
   } finally {

packages/now-cli/src/util/dev/builder.ts

@@ -56,6 +56,8 @@ async function createBuildProcess(
   workPath: string,
   output: Output
 ): Promise<ChildProcess> {
+  output.debug(`Creating build process for "${match.entrypoint}"`);
+
   const builderWorkerPath = join(__dirname, 'builder-worker.js');
 
   // Ensure that `node` is in the builder's `PATH`
@@ -78,7 +80,7 @@ async function createBuildProcess(
 
   buildProcess.on('exit', (code, signal) => {
     output.debug(
-      `Build process for ${match.src} exited with ${signal || code}`
+      `Build process for "${match.entrypoint}" exited with ${signal || code}`
     );
     match.buildProcess = undefined;
   });
@@ -128,7 +130,6 @@ export async function executeBuild(
 
   let { buildProcess } = match;
   if (!runInProcess && !buildProcess) {
-    devServer.output.debug(`Creating build process for ${entrypoint}`);
     buildProcess = await createBuildProcess(
       match,
       envConfigs,
@@ -431,7 +432,7 @@ export async function getBuildMatches(
     }
 
     const files = fileList
-      .filter(name => name === src || minimatch(name, src))
+      .filter(name => name === src || minimatch(name, src, { dot: true }))
       .map(name => join(cwd, name));
 
     if (files.length === 0) {

packages/now-cli/src/util/dev/server.ts

@@ -18,6 +18,7 @@ import directoryTemplate from 'serve-handler/src/directory';
 import getPort from 'get-port';
 import { ChildProcess } from 'child_process';
 import isPortReachable from 'is-port-reachable';
+import deepEqual from 'fast-deep-equal';
 import which from 'which';
 
 import { getVercelIgnore, fileNameSymbol } from '@vercel/client';
@@ -49,17 +50,7 @@ import { MissingDotenvVarsError } from '../errors-ts';
 import cliPkg from '../pkg';
 import { getVercelDirectory } from '../projects/link';
 import { staticFiles as getFiles, getAllProjectFiles } from '../get-files';
-import {
-  validateNowConfigBuilds,
-  validateNowConfigRoutes,
-  validateNowConfigCleanUrls,
-  validateNowConfigHeaders,
-  validateNowConfigRedirects,
-  validateNowConfigRewrites,
-  validateNowConfigTrailingSlash,
-  validateNowConfigFunctions,
-} from './validate';
-
+import { validateConfig } from './validate';
 import { devRouter, getRoutesTypes } from './router';
 import getMimeType from './mime-type';
 import { executeBuild, getBuildMatches, shutdownBuilder } from './builder';
@@ -92,6 +83,7 @@ import {
   HttpHeadersConfig,
   EnvConfigs,
 } from './types';
+import { ProjectSettings } from '../../types';
 
 interface FSEvent {
   type: string;
@@ -116,7 +108,7 @@ export default class DevServer {
   public output: Output;
   public proxy: httpProxy;
   public envConfigs: EnvConfigs;
-  public frameworkSlug: string | null;
+  public frameworkSlug?: string;
   public files: BuilderInputs;
   public address: string;
   public devCacheDir: string;
@@ -139,6 +131,7 @@ export default class DevServer {
   private devProcess?: ChildProcess;
   private devProcessPort?: number;
   private devServerPids: Set<number>;
+  private projectSettings?: ProjectSettings;
 
   private getNowConfigPromise: Promise<NowConfig> | null;
   private blockingBuildsPromise: Promise<void> | null;
@@ -153,6 +146,7 @@ export default class DevServer {
     this.files = {};
     this.address = '';
     this.devCommand = options.devCommand;
+    this.projectSettings = options.projectSettings;
     this.frameworkSlug = options.frameworkSlug;
     this.cachedNowConfig = null;
     this.caseSensitive = false;
@@ -234,8 +228,18 @@ export default class DevServer {
       }
     }
 
-    // Update the build matches in case an entrypoint was created or deleted
     const nowConfig = await this.getNowConfig(false);
+
+    // Update the env vars configuration
+    const nowConfigBuild = nowConfig.build || {};
+    const [runEnv, buildEnv] = await Promise.all([
+      this.getLocalEnv('.env', nowConfig.env),
+      this.getLocalEnv('.env.build', nowConfigBuild.env),
+    ]);
+    const allEnv = { ...buildEnv, ...runEnv };
+    this.envConfigs = { buildEnv, runEnv, allEnv };
+
+    // Update the build matches in case an entrypoint was created or deleted
     await this.updateBuildMatches(nowConfig);
 
     const filesChangedArray = [...filesChanged];
@@ -377,9 +381,7 @@ export default class DevServer {
     const sources = matches.map(m => m.src);
 
     if (isInitial && fileList.length === 0) {
-      this.output.warn(
-        'There are no files (or only files starting with a dot) inside your deployment.'
-      );
+      this.output.warn('There are no files inside your deployment.');
     }
 
     // Delete build matches that no longer exists
@@ -400,7 +402,7 @@ export default class DevServer {
     const blockingBuilds: Promise<void>[] = [];
     for (const match of matches) {
       const currentMatch = this.buildMatches.get(match.src);
-      if (!currentMatch || currentMatch.use !== match.use) {
+      if (!buildMatchEquals(currentMatch, match)) {
         this.output.debug(
           `Adding build match for "${match.src}" with "${match.use}"`
         );
@@ -435,6 +437,9 @@ export default class DevServer {
             `Cleaning up "blockingBuildsPromise" after error: ${err}`
           );
           this.blockingBuildsPromise = null;
+          if (err) {
+            this.output.prettyError(err);
+          }
         });
     }
 
@@ -522,23 +527,16 @@ export default class DevServer {
     // The default empty `vercel.json` is used to serve all files as static
     // when no `vercel.json` is present
     let configPath = 'vercel.json';
-    let config: NowConfig = this.cachedNowConfig || {
+    let config: NowConfig = {
       version: 2,
       [fileNameSymbol]: configPath,
     };
 
-    // We need to delete these properties for zero config to work
-    // with file changes
-    if (this.cachedNowConfig) {
-      delete this.cachedNowConfig.builds;
-      delete this.cachedNowConfig.routes;
-    }
-
     try {
       configPath = getNowConfigPath(this.cwd);
       this.output.debug(`Reading ${configPath}`);
       config = JSON.parse(await fs.readFile(configPath, 'utf8'));
-      config[fileNameSymbol] = configPath;
+      config[fileNameSymbol] = basename(configPath);
     } catch (err) {
       if (err.code === 'ENOENT') {
         this.output.debug(err.toString());
@@ -585,7 +583,7 @@ export default class DevServer {
       } = await detectBuilders(files, pkg, {
         tag: getDistTag(cliPkg.version) === 'canary' ? 'canary' : 'latest',
         functions: config.functions,
-        ...(projectSettings ? { projectSettings } : {}),
+        projectSettings: projectSettings || this.projectSettings,
         featHandleMiss,
         cleanUrls,
         trailingSlash,
@@ -689,14 +687,12 @@ export default class DevServer {
       return;
     }
 
-    await this.tryValidateOrExit(config, validateNowConfigBuilds);
-    await this.tryValidateOrExit(config, validateNowConfigRoutes);
-    await this.tryValidateOrExit(config, validateNowConfigCleanUrls);
-    await this.tryValidateOrExit(config, validateNowConfigHeaders);
-    await this.tryValidateOrExit(config, validateNowConfigRedirects);
-    await this.tryValidateOrExit(config, validateNowConfigRewrites);
-    await this.tryValidateOrExit(config, validateNowConfigTrailingSlash);
-    await this.tryValidateOrExit(config, validateNowConfigFunctions);
+    const error = validateConfig(config);
+
+    if (error) {
+      this.output.prettyError(error);
+      await this.exit(1);
+    }
   }
 
   validateEnvConfig(type: string, env: Env = {}, localEnv: Env = {}): Env {
@@ -773,7 +769,6 @@ export default class DevServer {
       this.getLocalEnv('.env.build', nowConfigBuild.env),
     ]);
     const allEnv = { ...buildEnv, ...runEnv };
-    Object.assign(process.env, allEnv);
     this.envConfigs = { buildEnv, runEnv, allEnv };
 
     const opts = { output: this.output, isBuilds: true };
@@ -1500,16 +1495,15 @@ export default class DevServer {
     if (!match) {
       // If the dev command is started, then proxy to it
       if (this.devProcessPort) {
-        debug('Proxying to frontend dev server');
+        const upstream = `http://localhost:${this.devProcessPort}`;
+        debug(`Proxying to frontend dev server: ${upstream}`);
         this.setResponseHeaders(res, nowRequestId);
-        return proxyPass(
-          req,
-          res,
-          `http://localhost:${this.devProcessPort}`,
-          this,
-          nowRequestId,
-          false
-        );
+        const origUrl = url.parse(req.url || '/', true);
+        delete origUrl.search;
+        origUrl.pathname = dest;
+        Object.assign(origUrl.query, uri_args);
+        req.url = url.format(origUrl);
+        return proxyPass(req, res, upstream, this, nowRequestId, false);
       }
 
       if (
@@ -2200,7 +2194,9 @@ function isIndex(path: string): boolean {
 }
 
 function minimatches(files: string[], pattern: string): boolean {
-  return files.some(file => file === pattern || minimatch(file, pattern));
+  return files.some(
+    file => file === pattern || minimatch(file, pattern, { dot: true })
+  );
 }
 
 function fileChanged(
@@ -2261,3 +2257,11 @@ function hasNewRoutingProperties(nowConfig: NowConfig) {
     typeof nowConfig.trailingSlash !== undefined
   );
 }
+
+function buildMatchEquals(a?: BuildMatch, b?: BuildMatch): boolean {
+  if (!a || !b) return false;
+  if (a.src !== b.src) return false;
+  if (a.use !== b.use) return false;
+  if (!deepEqual(a.config || {}, b.config || {})) return false;
+  return true;
+}

packages/now-cli/src/util/dev/types.ts

@@ -17,14 +17,16 @@ import {
 import { NowConfig } from '@vercel/client';
 import { HandleValue, Route } from '@vercel/routing-utils';
 import { Output } from '../output';
+import { ProjectSettings } from '../../types';
 
 export { NowConfig };
 
 export interface DevServerOptions {
   output: Output;
   debug: boolean;
-  devCommand: string | undefined;
-  frameworkSlug: string | null;
+  devCommand?: string;
+  frameworkSlug?: string;
+  projectSettings?: ProjectSettings;
 }
 
 export interface EnvConfigs {

packages/now-cli/src/util/dev/validate.ts

@@ -8,71 +8,44 @@ import {
   trailingSlashSchema,
 } from '@vercel/routing-utils';
 import { NowConfig } from './types';
-import { functionsSchema, buildsSchema } from '@vercel/build-utils';
+import {
+  functionsSchema,
+  buildsSchema,
+  NowBuildError,
+  getPrettyError,
+} from '@vercel/build-utils';
+import { fileNameSymbol } from '@vercel/client';
+
+const vercelConfigSchema = {
+  type: 'object',
+  // These are not all possibilities because `vc dev`
+  // doesn't need to know about `regions`, `public`, etc.
+  additionalProperties: true,
+  properties: {
+    builds: buildsSchema,
+    routes: routesSchema,
+    cleanUrls: cleanUrlsSchema,
+    headers: headersSchema,
+    redirects: redirectsSchema,
+    rewrites: rewritesSchema,
+    trailingSlash: trailingSlashSchema,
+    functions: functionsSchema,
+  },
+};
 
 const ajv = new Ajv();
 
-const validateBuilds = ajv.compile(buildsSchema);
-const validateRoutes = ajv.compile(routesSchema);
-const validateCleanUrls = ajv.compile(cleanUrlsSchema);
-const validateHeaders = ajv.compile(headersSchema);
-const validateRedirects = ajv.compile(redirectsSchema);
-const validateRewrites = ajv.compile(rewritesSchema);
-const validateTrailingSlash = ajv.compile(trailingSlashSchema);
-const validateFunctions = ajv.compile(functionsSchema);
+export function validateConfig(config: NowConfig): NowBuildError | null {
+  const validate = ajv.compile(vercelConfigSchema);
 
-export function validateNowConfigBuilds(config: NowConfig) {
-  return validateKey(config, 'builds', validateBuilds);
-}
-
-export function validateNowConfigRoutes(config: NowConfig) {
-  return validateKey(config, 'routes', validateRoutes);
-}
-
-export function validateNowConfigCleanUrls(config: NowConfig) {
-  return validateKey(config, 'cleanUrls', validateCleanUrls);
-}
-
-export function validateNowConfigHeaders(config: NowConfig) {
-  return validateKey(config, 'headers', validateHeaders);
-}
-
-export function validateNowConfigRedirects(config: NowConfig) {
-  return validateKey(config, 'redirects', validateRedirects);
-}
-
-export function validateNowConfigRewrites(config: NowConfig) {
-  return validateKey(config, 'rewrites', validateRewrites);
-}
-
-export function validateNowConfigTrailingSlash(config: NowConfig) {
-  return validateKey(config, 'trailingSlash', validateTrailingSlash);
-}
-
-export function validateNowConfigFunctions(config: NowConfig) {
-  return validateKey(config, 'functions', validateFunctions);
-}
-
-function validateKey(
-  config: NowConfig,
-  key: keyof NowConfig,
-  validate: Ajv.ValidateFunction
-) {
-  const value = config[key];
-  if (!value) {
-    return null;
-  }
-
-  if (!validate(value)) {
-    if (!validate.errors) {
-      return null;
+  if (!validate(config)) {
+    if (validate.errors && validate.errors[0]) {
+      const error = validate.errors[0];
+      const fileName = config[fileNameSymbol] || 'vercel.json';
+      const niceError = getPrettyError(error);
+      niceError.message = `Invalid ${fileName} - ${niceError.message}`;
+      return niceError;
     }
-
-    const error = validate.errors[0];
-
-    return `Invalid \`${String(key)}\` property: ${error.dataPath} ${
-      error.message
-    }`;
   }
 
   return null;

packages/now-cli/src/util/errors-ts.ts

@@ -1,5 +1,6 @@
 import bytes from 'bytes';
 import { Response } from 'node-fetch';
+import { NowBuildError } from '@vercel/build-utils';
 import { NowError } from './now-error';
 import code from './output/code';
 import { getCommandName } from './pkg-name';
@@ -771,17 +772,17 @@ export class CantParseJSONFile extends NowError<
   }
 }
 
-export class ConflictingConfigFiles extends NowError<
-  'CONFLICTING_CONFIG_FILES',
-  { files: string[] }
-> {
+export class ConflictingConfigFiles extends NowBuildError {
+  files: string[];
+
   constructor(files: string[]) {
     super({
       code: 'CONFLICTING_CONFIG_FILES',
-      meta: { files },
       message:
         'Cannot use both a `vercel.json` and `now.json` file. Please delete the `now.json` file.',
+      link: 'https://vercel.link/combining-old-and-new-config',
     });
+    this.files = files;
   }
 }
 

packages/now-cli/src/util/index.js

@@ -145,6 +145,7 @@ export default class Now extends EventEmitter {
       regions,
       target: target || undefined,
       projectSettings,
+      source: 'cli',
     };
 
     // Ignore specific items from vercel.json

packages/now-cli/src/util/output/error.ts

@@ -1,6 +1,7 @@
 import chalk from 'chalk';
 import { metrics, shouldCollectMetrics } from '../metrics';
 import { APIError } from '../errors-ts';
+import renderLink from './link';
 
 const metric = metrics();
 
@@ -9,10 +10,9 @@ export default function error(...input: string[] | [APIError]) {
   if (typeof input[0] === 'object') {
     const { slug, message, link } = input[0];
     messages = [message];
-    if (slug) {
-      messages.push(`> More details: https://err.sh/now/${slug}`);
-    } else if (link) {
-      messages.push(`> More details: ${link}`);
+    const details = slug ? `https://err.sh/now/${slug}` : link;
+    if (details) {
+      messages.push(`${chalk.bold('More details')}: ${renderLink(details)}`);
     }
   }
 

packages/now-cli/src/util/projects/link.ts

@@ -14,7 +14,7 @@ import chalk from 'chalk';
 import { prependEmoji, emoji } from '../emoji';
 import AJV from 'ajv';
 import { isDirectory } from '../config/global-path';
-import { getPlatformEnv } from '@vercel/build-utils';
+import { NowBuildError, getPlatformEnv } from '@vercel/build-utils';
 
 const readFile = promisify(fs.readFile);
 const writeFile = promisify(fs.writeFile);
@@ -49,9 +49,12 @@ export function getVercelDirectory(cwd: string = process.cwd()): string {
   const possibleDirs = [join(cwd, VERCEL_DIR), join(cwd, VERCEL_DIR_FALLBACK)];
   const existingDirs = possibleDirs.filter(d => isDirectory(d));
   if (existingDirs.length > 1) {
-    throw new Error(
-      'Both `.vercel` and `.now` directories exist. Please remove the `.now` directory.'
-    );
+    throw new NowBuildError({
+      code: 'CONFLICTING_CONFIG_DIRECTORIES',
+      message:
+        'Both `.vercel` and `.now` directories exist. Please remove the `.now` directory.',
+      link: 'https://vercel.link/combining-old-and-new-config',
+    });
   }
   return existingDirs[0] || possibleDirs[0];
 }

packages/now-cli/test/dev-validate.unit.js

@@ -0,0 +1,262 @@
+import test from 'ava';
+import { validateConfig } from '../src/util/dev/validate';
+
+test('[dev-validate] should not error with empty config', async t => {
+  const config = {};
+  const error = validateConfig(config);
+  t.deepEqual(error, null);
+});
+
+test('[dev-validate] should not error with complete config', async t => {
+  const config = {
+    version: 2,
+    public: true,
+    regions: ['sfo1', 'iad1'],
+    builds: [{ src: 'package.json', use: '@vercel/next' }],
+    cleanUrls: true,
+    headers: [{ source: '/', headers: [{ key: 'x-id', value: '123' }] }],
+    rewrites: [{ source: '/help', destination: '/support' }],
+    redirects: [{ source: '/kb', destination: 'https://example.com' }],
+    trailingSlash: false,
+    functions: { 'api/user.go': { memory: 128, maxDuration: 5 } },
+  };
+  const error = validateConfig(config);
+  t.deepEqual(error, null);
+});
+
+test('[dev-validate] should not error with builds and routes', async t => {
+  const config = {
+    builds: [{ src: 'api/index.js', use: '@vercel/node' }],
+    routes: [{ src: '/(.*)', dest: '/api/index.js' }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(error, null);
+});
+
+test('[dev-validate] should error with invalid rewrites due to additional property and offer suggestion', async t => {
+  const config = {
+    rewrites: [{ src: '/(.*)', dest: '/api/index.js' }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `rewrites[0]` should NOT have additional property `src`. Did you mean `source`?'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/rewrites'
+  );
+});
+
+test('[dev-validate] should error with invalid routes due to additional property and offer suggestion', async t => {
+  const config = {
+    routes: [{ source: '/(.*)', destination: '/api/index.js' }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `routes[0]` should NOT have additional property `source`. Did you mean `src`?'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/routes'
+  );
+});
+
+test('[dev-validate] should error with invalid routes array type', async t => {
+  const config = {
+    routes: { src: '/(.*)', dest: '/api/index.js' },
+  };
+  const error = validateConfig(config);
+  t.deepEqual(error.message, 'Invalid vercel.json - `routes` should be array.');
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/routes'
+  );
+});
+
+test('[dev-validate] should error with invalid redirects array object', async t => {
+  const config = {
+    redirects: [
+      {
+        /* intentionally empty */
+      },
+    ],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `redirects[0]` missing required property `source`.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/redirects'
+  );
+});
+
+test('[dev-validate] should error with invalid redirects.permanent poperty', async t => {
+  const config = {
+    redirects: [{ source: '/', destination: '/go', permanent: 'yes' }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `redirects[0].permanent` should be boolean.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/redirects'
+  );
+});
+
+test('[dev-validate] should error with invalid cleanUrls type', async t => {
+  const config = {
+    cleanUrls: 'true',
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `cleanUrls` should be boolean.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/cleanurls'
+  );
+});
+
+test('[dev-validate] should error with invalid trailingSlash type', async t => {
+  const config = {
+    trailingSlash: [true],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `trailingSlash` should be boolean.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/trailingslash'
+  );
+});
+
+test('[dev-validate] should error with invalid headers property', async t => {
+  const config = {
+    headers: [{ 'Content-Type': 'text/html' }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[0]` should NOT have additional property `Content-Type`. Please remove it.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});
+
+test('[dev-validate] should error with invalid headers.source type', async t => {
+  const config = {
+    headers: [{ source: [{ 'Content-Type': 'text/html' }] }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[0].source` should be string.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});
+
+test('[dev-validate] should error with invalid headers additional property', async t => {
+  const config = {
+    headers: [{ source: '/', stuff: [{ 'Content-Type': 'text/html' }] }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[0]` should NOT have additional property `stuff`. Please remove it.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});
+
+test('[dev-validate] should error with invalid headers wrong nested headers type', async t => {
+  const config = {
+    headers: [{ source: '/', headers: [{ 'Content-Type': 'text/html' }] }],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[0].headers[0]` should NOT have additional property `Content-Type`. Please remove it.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});
+
+test('[dev-validate] should error with invalid headers wrong nested headers additional property', async t => {
+  const config = {
+    headers: [
+      { source: '/', headers: [{ key: 'Content-Type', val: 'text/html' }] },
+    ],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[0].headers[0]` should NOT have additional property `val`. Please remove it.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});
+
+test('[dev-validate] should error with too many redirects', async t => {
+  const config = {
+    redirects: Array.from({ length: 5000 }).map((_, i) => ({
+      source: `/${i}`,
+      destination: `/v/${i}`,
+    })),
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `redirects` should NOT have more than 1024 items.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/redirects'
+  );
+});
+
+test('[dev-validate] should error with too many nested headers', async t => {
+  const config = {
+    headers: [
+      {
+        source: '/',
+        headers: [{ key: `x-id`, value: `123` }],
+      },
+      {
+        source: '/too-many',
+        headers: Array.from({ length: 5000 }).map((_, i) => ({
+          key: `${i}`,
+          value: `${i}`,
+        })),
+      },
+    ],
+  };
+  const error = validateConfig(config);
+  t.deepEqual(
+    error.message,
+    'Invalid vercel.json - `headers[1].headers` should NOT have more than 1024 items.'
+  );
+  t.deepEqual(
+    error.link,
+    'https://vercel.com/docs/configuration#project/headers'
+  );
+});

packages/now-cli/test/dev/fixtures/00-list-directory/.well-known/keybase.txt

@@ -0,0 +1 @@
+proof goes here

packages/now-cli/test/dev/fixtures/06-gridsome/package.json

@@ -3,7 +3,7 @@
   "private": true,
   "scripts": {
     "build": "gridsome build",
-    "develop": "gridsome develop",
+    "dev": "gridsome develop -p $PORT",
     "explore": "gridsome explore"
   },
   "dependencies": {

packages/now-cli/test/dev/fixtures/06-gridsome/src/pages/404.vue

@@ -0,0 +1,14 @@
+<template>
+  <Layout>
+    <h1>Not Found</h1>
+    <p>This is a Custom Gridsome 404.</p>
+  </Layout>
+</template>
+
+<script>
+export default {
+  metaInfo: {
+    title: 'Not Found'
+  }
+}
+</script>

packages/now-cli/test/dev/fixtures/06-gridsome/src/pages/Index.vue

@@ -1,11 +1,11 @@
 <template>
   <Layout>
-    
+
     <!-- Learn how to use images here: https://gridsome.org/docs/images -->
     <g-image alt="Example image" src="~/favicon.png" width="135" />
-    
-    <h1>Hello, world!</h1>
-   
+
+    <h1>Gridsome on Vercel</h1>
+
     <p>
       Lorem ipsum dolor sit amet, consectetur adipisicing elit. Pariatur excepturi labore tempore expedita, et iste tenetur suscipit explicabo! Dolores, aperiam non officia eos quod asperiores
     </p>

packages/now-cli/test/dev/fixtures/06-gridsome/vercel.json

@@ -0,0 +1,3 @@
+{
+  "redirects": [{ "source": "/support", "destination": "/about?ref=support" }]
+}

packages/now-cli/test/dev/fixtures/07-hexo-node/source/contact.html

@@ -0,0 +1 @@
+<h1>Contact Us</h1>

packages/now-cli/test/dev/fixtures/07-hexo-node/vercel.json

@@ -0,0 +1,3 @@
+{
+  "rewrites": [{ "source": "/support", "destination": "/contact.html" }]
+}

packages/now-cli/test/dev/fixtures/10-nextjs-node/pages/contact.js

@@ -0,0 +1,3 @@
+export default function Contact() {
+  return <h1>Contact Page</h1>;
+}

packages/now-cli/test/dev/fixtures/10-nextjs-node/vercel.json

@@ -0,0 +1,3 @@
+{
+  "rewrites": [{ "source": "/support", "destination": "/contact" }]
+}

packages/now-cli/test/dev/fixtures/force-module-commonjs/.gitignore

@@ -0,0 +1 @@
+.vercel

packages/now-cli/test/dev/fixtures/force-module-commonjs/api/index.js

@@ -0,0 +1,3 @@
+export default function(req, res) {
+  res.end('Force "module: commonjs" JavaScript with ES Modules API endpoint');
+}

packages/now-cli/test/dev/fixtures/force-module-commonjs/api/ts.ts

@@ -0,0 +1,5 @@
+import { IncomingMessage, ServerResponse } from 'http';
+
+export default function(req: IncomingMessage, res: ServerResponse) {
+  res.end('Force "module: commonjs" TypeScript API endpoint');
+}

packages/now-cli/test/dev/fixtures/force-module-commonjs/next-env.d.ts

@@ -0,0 +1,2 @@
+/// <reference types="next" />
+/// <reference types="next/types/global" />

packages/now-cli/test/dev/fixtures/force-module-commonjs/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "force-module-commonjs",
+  "private": true,
+  "scripts": {
+    "dev": "next",
+    "build": "next build",
+    "start": "next start"
+  },
+  "dependencies": {
+    "next": "^9.3.4",
+    "react": "^16.13.1",
+    "react-dom": "^16.13.1"
+  },
+  "devDependencies": {
+    "@types/node": "14.0.9",
+    "@types/react": "^16.9.32",
+    "typescript": "^3.8.3"
+  }
+}

packages/now-cli/test/dev/fixtures/force-module-commonjs/pages/index.tsx

@@ -0,0 +1,3 @@
+export default function () {
+  return <div>Force "module: commonjs" test page</div>;
+}

packages/now-cli/test/dev/fixtures/force-module-commonjs/tsconfig.json

@@ -0,0 +1,25 @@
+{
+  "compilerOptions": {
+    "baseUrl": ".",
+    "target": "esnext",
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "allowSyntheticDefaultImports": true,
+    "forceConsistentCasingInFileNames": true,
+    "noEmit": true,
+    "esModuleInterop": true,
+    "module": "esnext",
+    "moduleResolution": "node",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "preserve",
+    "paths": {
+      "@components/*": ["components/*"],
+      "@lib/*": ["lib/*"]
+    }
+  },
+  "exclude": ["node_modules", "api"],
+  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx"]
+}

packages/now-cli/test/dev/fixtures/go/.gitignore

@@ -0,0 +1 @@
+.vercel

packages/now-cli/test/dev/fixtures/go/api/[segment].go

@@ -0,0 +1,10 @@
+package handler
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func Handler(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "Req Path: %s", r.URL.Path)
+}

packages/now-cli/test/dev/fixtures/go/api/another.go

@@ -0,0 +1,10 @@
+package another
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func Another(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "This is another page")
+}

packages/now-cli/test/dev/fixtures/go/api/index.go

@@ -0,0 +1,10 @@
+package handler
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func Handler(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "This is the index page")
+}

packages/now-cli/test/dev/fixtures/invalidate-vercel-config/api/index.js

@@ -0,0 +1,3 @@
+export default (req, res) => {
+  res.send(process.env);
+};

packages/now-cli/test/dev/fixtures/invalidate-vercel-config/vercel.json

@@ -0,0 +1 @@
+{ "env": { "FOO": "bar" } }

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/blog/next.config.js

@@ -0,0 +1,6 @@
+module.exports = {
+  assetPrefix: '/blog',
+  env: {
+    ASSET_PREFIX: '/blog',
+  },
+};

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/blog/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "with-zones-blog",
+  "version": "1.0.0",
+  "dependencies": {
+    "next": "latest",
+    "react": "latest",
+    "react-dom": "latest"
+  },
+  "license": "ISC"
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/blog/pages/blog/index.js

@@ -0,0 +1,22 @@
+import Link from 'next/link';
+
+export default function Blog() {
+  return (
+    <div>
+      <h3>This is our blog</h3>
+      <ul>
+        <li>
+          <Link href="/blog/post/[id]" as="/blog/post/1">
+            <a>Post 1</a>
+          </Link>
+        </li>
+        <li>
+          <Link href="/blog/post/[id]" as="/blog/post/2">
+            <a>Post 2</a>
+          </Link>
+        </li>
+      </ul>
+      <a href="/">Home</a>
+    </div>
+  );
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/blog/pages/blog/post/[id].js

@@ -0,0 +1,15 @@
+import Link from 'next/link'
+import { useRouter } from 'next/router'
+
+export default function Post() {
+  const router = useRouter()
+  return (
+    <div>
+      <h3>Post #{router.query.id}</h3>
+      <p>Lorem ipsum</p>
+      <Link href="/blog">
+        <a>Back to blog</a>
+      </Link>
+    </div>
+  )
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/components/Header.js

@@ -0,0 +1,7 @@
+const Header = () => (
+  <div>
+    <h2>The Company</h2>
+  </div>
+);
+
+export default Header;

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "with-zones-home",
+  "version": "1.0.0",
+  "dependencies": {
+    "next": "latest",
+    "react": "latest",
+    "react-dom": "latest"
+  },
+  "license": "ISC"
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/pages/1/[id].js

@@ -0,0 +1,21 @@
+import Link from 'next/link';
+
+const About = ({ id }) => {
+  return (
+    <div>
+      <p>This is the {id} page with static props.</p>
+      <div>
+        <Link href="/">
+          <a>Go Back</a>
+        </Link>
+      </div>
+    </div>
+  );
+};
+
+export const getStaticProps = ({ params }) => {
+  return { props: { id: params.id } };
+};
+export const getStaticPaths = () => ({ paths: ['/1/dynamic'], fallback: true });
+
+export default About;

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/pages/[id].js

@@ -0,0 +1,19 @@
+import Link from 'next/link';
+import { useRouter } from 'next/router';
+
+const About = () => {
+  const router = useRouter();
+  const { id } = router.query;
+  return (
+    <div>
+      <p>This is the {id} page without static props.</p>
+      <div>
+        <Link href="/">
+          <a>Go Back</a>
+        </Link>
+      </div>
+    </div>
+  );
+};
+
+export default About;

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/pages/about.js

@@ -0,0 +1,19 @@
+import Link from 'next/link';
+import { useRouter } from 'next/router';
+
+const About = () => {
+  const router = useRouter();
+  const { id } = router.query;
+  return (
+    <div>
+      <p>This is the about static page.</p>
+      <div>
+        <Link href="/">
+          <a>Go Back</a>
+        </Link>
+      </div>
+    </div>
+  );
+};
+
+export default About;

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/home/pages/index.js

@@ -0,0 +1,36 @@
+import Link from 'next/link';
+import dynamic from 'next/dynamic';
+
+const Header = dynamic(import('../components/Header'));
+
+export default function Home() {
+  return (
+    <div>
+      <Header />
+      <p>This is our homepage</p>
+      <div>
+        <a href="/blog">Blog</a>
+      </div>
+      <div>
+        <Link href="/about">
+          <a>About us</a>
+        </Link>
+      </div>
+      <div>
+        <Link href="/foo">
+          <a>foo</a>
+        </Link>
+      </div>
+      <div>
+        <Link href="/1/dynamic">
+          <a>1/dynamic</a>
+        </Link>
+      </div>
+      <div>
+        <Link href="/1/foo">
+          <a>1/foo</a>
+        </Link>
+      </div>
+    </div>
+  );
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "with-zones-example",
+  "private": true,
+  "workspaces": [
+    "home",
+    "blog"
+  ],
+  "devDependencies": {
+    "vercel": "canary"
+  }
+}

packages/now-cli/test/dev/fixtures/monorepo-dynamic-paths/vercel.json

@@ -0,0 +1,12 @@
+{
+  "version": 2,
+  "builds": [
+    { "src": "blog/package.json", "use": "@vercel/next@canary" },
+    { "src": "home/package.json", "use": "@vercel/next@canary" }
+  ],
+  "routes": [
+    { "src": "/blog/_next(.*)", "dest": "blog/_next$1" },
+    { "src": "/blog(.*)", "dest": "blog/blog$1" },
+    { "src": "(.*)", "dest": "home$1" }
+  ]
+}

packages/now-cli/test/dev/fixtures/node-helpers/index.js

@@ -0,0 +1,10 @@
+export default (req, res) => {
+  const hasHelpers = typeof req.query !== 'undefined';
+  res.setHeader('Content-Type', 'application/json');
+  res.end(
+    JSON.stringify({
+      hasHelpers,
+      query: req.query,
+    })
+  );
+};

packages/now-cli/test/dev/fixtures/node-helpers/vercel.json

@@ -0,0 +1 @@
+{ "builds": [{ "src": "index.js", "use": "@vercel/node@canary" }] }

packages/now-cli/test/dev/fixtures/node-ts-node-target/api/array.js

@@ -0,0 +1,4 @@
+module.exports = (req, res) => {
+  const months = [...Array(12).keys()].map(month => month + 1);
+  res.json({ months });
+};

packages/now-cli/test/dev/fixtures/node-ts-node-target/api/subclass.js

@@ -0,0 +1,15 @@
+const { PCRE } = require('pcre-to-regexp');
+
+// `ts-node` default "target" is "es5" which transpiles `class` statements and
+// is incompatible with dependencies that use ES6 native `class`. Setting the
+// "target" to "es2018" or newer prevents the `class` transpilation.
+//
+// See: https://github.com/vercel/vercel/discussions/4724
+// See: https://github.com/TypeStrong/ts-node/issues/903
+class P extends PCRE {}
+
+export default (req, res) => {
+  const p = new P('hi'); // This line should not throw an error
+  console.log(p);
+  res.send({ ok: true });
+};

packages/now-cli/test/dev/fixtures/node-ts-node-target/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "node-ts-node-target",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "pcre-to-regexp": "1.1.0"
+  }
+}

packages/now-cli/test/dev/fixtures/node-ts-node-target/tsconfig.json

@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "module": "CommonJS"
+  }
+}

packages/now-cli/test/dev/fixtures/node-ts-node-target/yarn.lock

@@ -0,0 +1,8 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+pcre-to-regexp@1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/pcre-to-regexp/-/pcre-to-regexp-1.1.0.tgz#1c48373d194b982e1416031b41470839fab3ad6c"
+  integrity sha512-KF9XxmUQJ2DIlMj3TqNqY1AWvyvTuIuq11CuuekxyaYMiFuMKGgQrePYMX5bXKLhLG3sDI4CsGAYHPaT7VV7+g==

packages/now-cli/test/dev/fixtures/public-and-api/public/.well-known/humans.txt

@@ -0,0 +1 @@
+We come in peace

packages/now-cli/test/dev/integration.js

@@ -1,4 +1,5 @@
 import ms from 'ms';
+import os from 'os';
 import fs from 'fs-extra';
 import test from 'ava';
 import { join, resolve, delimiter } from 'path';
@@ -161,7 +162,7 @@ async function testPath(
     Object.entries(headers).forEach(([key, expectedValue]) => {
       let actualValue = res.headers.get(key);
       if (key.toLowerCase() === 'location' && actualValue === '//') {
-        // HACK: `node-fetch` has strang behavior for location header so fix it
+        // HACK: `node-fetch` has strange behavior for location header so fix it
         // with `manual-dont-change` opt and convert double slash to single.
         // See https://github.com/node-fetch/node-fetch/issues/417#issuecomment-587233352
         actualValue = '/';
@@ -187,20 +188,29 @@ async function testFixture(directory, opts = {}, args = []) {
     }
   );
 
-  const stdoutList = [];
-  const stderrList = [];
-
+  let stdout = '';
+  let stderr = '';
+  const readyResolver = createResolver();
   const exitResolver = createResolver();
 
-  dev.stderr.on('data', data => stderrList.push(Buffer.from(data)));
-  dev.stdout.on('data', data => stdoutList.push(Buffer.from(data)));
+  dev.stdout.setEncoding('utf8');
+  dev.stderr.setEncoding('utf8');
+
+  dev.stdout.on('data', data => {
+    stdout += data;
+  });
+  dev.stderr.on('data', data => {
+    stderr += data;
+
+    if (stderr.includes('Ready! Available at')) {
+      readyResolver.resolve();
+    }
+  });
 
   let printedOutput = false;
 
   dev.on('exit', () => {
     if (!printedOutput) {
-      const stdout = Buffer.concat(stdoutList).toString();
-      const stderr = Buffer.concat(stderrList).toString();
       printOutput(directory, stdout, stderr);
       printedOutput = true;
     }
@@ -209,8 +219,6 @@ async function testFixture(directory, opts = {}, args = []) {
 
   dev.on('error', () => {
     if (!printedOutput) {
-      const stdout = Buffer.concat(stdoutList).toString();
-      const stderr = Buffer.concat(stderrList).toString();
       printOutput(directory, stdout, stderr);
       printedOutput = true;
     }
@@ -226,6 +234,7 @@ async function testFixture(directory, opts = {}, args = []) {
   return {
     dev,
     port,
+    readyResolver,
   };
 }
 
@@ -267,14 +276,12 @@ function testFixtureStdio(
 
     await runNpmInstall(cwd);
 
-    const stdoutList = [];
-    const stderrList = [];
-
+    let stdout = '';
+    let stderr = '';
     const readyResolver = createResolver();
     const exitResolver = createResolver();
 
     try {
-      let stderr = '';
       let printedOutput = false;
 
       const env = skipDeploy
@@ -285,17 +292,19 @@ function testFixtureStdio(
         env,
       });
 
+      dev.stdout.setEncoding('utf8');
+      dev.stderr.setEncoding('utf8');
+
       dev.stdout.pipe(process.stdout);
       dev.stderr.pipe(process.stderr);
 
       dev.stdout.on('data', data => {
-        stdoutList.push(data);
+        stdout += data;
       });
 
       dev.stderr.on('data', data => {
-        stderrList.push(data);
+        stderr += data;
 
-        stderr += data.toString();
         if (stderr.includes('Ready! Available at')) {
           readyResolver.resolve();
         }
@@ -315,8 +324,6 @@ function testFixtureStdio(
 
       dev.on('exit', () => {
         if (!printedOutput) {
-          const stdout = Buffer.concat(stdoutList).toString();
-          const stderr = Buffer.concat(stderrList).toString();
           printOutput(directory, stdout, stderr);
           printedOutput = true;
         }
@@ -325,8 +332,6 @@ function testFixtureStdio(
 
       dev.on('error', () => {
         if (!printedOutput) {
-          const stdout = Buffer.concat(stdoutList).toString();
-          const stderr = Buffer.concat(stderrList).toString();
           printOutput(directory, stdout, stderr);
           printedOutput = true;
         }
@@ -382,7 +387,173 @@ test('[vercel dev] prints `npm install` errors', async t => {
   t.truthy(
     result.stderr.includes('Failed to install `vercel dev` dependencies')
   );
-  t.truthy(result.stderr.includes('https://vercel.link/npm-install-error'));
+  t.truthy(
+    result.stderr.includes('https://vercel.link/npm-install-failed-dev')
+  );
+});
+
+test('[vercel dev] `vercel.json` should be invalidated if deleted', async t => {
+  const dir = fixture('invalidate-vercel-config');
+  const configPath = join(dir, 'vercel.json');
+  const originalConfig = await fs.readJSON(configPath);
+  const { dev, port, readyResolver } = await testFixture(dir);
+
+  try {
+    await readyResolver;
+
+    {
+      // Env var should be set from `vercel.json`
+      const res = await fetch(`http://localhost:${port}/api`);
+      const body = await res.json();
+      t.is(body.FOO, 'bar');
+    }
+
+    {
+      // Env var should not be set after `vercel.json` is deleted
+      await fs.remove(configPath);
+      await sleep(1000);
+
+      const res = await fetch(`http://localhost:${port}/api`);
+      const body = await res.json();
+      t.is(body.FOO, undefined);
+    }
+  } finally {
+    await dev.kill('SIGTERM');
+    await fs.writeJSON(configPath, originalConfig);
+  }
+});
+
+test('[vercel dev] reflects changes to config and env without restart', async t => {
+  const dir = fixture('node-helpers');
+  const configPath = join(dir, 'vercel.json');
+  const originalConfig = await fs.readJSON(configPath);
+  const { dev, port, readyResolver } = await testFixture(dir);
+
+  try {
+    await readyResolver;
+
+    {
+      // Node.js helpers should be available by default
+      const res = await fetch(`http://localhost:${port}/?foo=bar`);
+      const body = await res.json();
+      t.is(body.hasHelpers, true);
+      t.is(body.query.foo, 'bar');
+    }
+
+    {
+      // Disable the helpers via `config.helpers = false`
+      const config = {
+        ...originalConfig,
+        builds: [
+          {
+            ...originalConfig.builds[0],
+            config: {
+              helpers: false,
+            },
+          },
+        ],
+      };
+      await fs.writeJSON(configPath, config);
+      await sleep(1000);
+
+      const res = await fetch(`http://localhost:${port}/?foo=bar`);
+      const body = await res.json();
+      t.is(body.hasHelpers, false);
+      t.is(body.query, undefined);
+    }
+
+    {
+      // Enable the helpers via `config.helpers = true`
+      const config = {
+        ...originalConfig,
+        builds: [
+          {
+            ...originalConfig.builds[0],
+            config: {
+              helpers: true,
+            },
+          },
+        ],
+      };
+      await fs.writeJSON(configPath, config);
+      await sleep(1000);
+
+      const res = await fetch(`http://localhost:${port}/?foo=baz`);
+      const body = await res.json();
+      t.is(body.hasHelpers, true);
+      t.is(body.query.foo, 'baz');
+    }
+
+    {
+      // Disable the helpers via `NODEJS_HELPERS = '0'`
+      const config = {
+        ...originalConfig,
+        build: {
+          env: {
+            NODEJS_HELPERS: '0',
+          },
+        },
+      };
+      await fs.writeJSON(configPath, config);
+      await sleep(1000);
+
+      const res = await fetch(`http://localhost:${port}/?foo=baz`);
+      const body = await res.json();
+      t.is(body.hasHelpers, false);
+      t.is(body.query, undefined);
+    }
+
+    {
+      // Enable the helpers via `NODEJS_HELPERS = '1'`
+      const config = {
+        ...originalConfig,
+        build: {
+          env: {
+            NODEJS_HELPERS: '1',
+          },
+        },
+      };
+      await fs.writeJSON(configPath, config);
+      await sleep(1000);
+
+      const res = await fetch(`http://localhost:${port}/?foo=boo`);
+      const body = await res.json();
+      t.is(body.hasHelpers, true);
+      t.is(body.query.foo, 'boo');
+    }
+  } finally {
+    await dev.kill('SIGTERM');
+    await fs.writeJSON(configPath, originalConfig);
+  }
+});
+
+test('[vercel dev] `@vercel/node` TypeScript should be resolved by default', async t => {
+  // The purpose of this test is to test that `@vercel/node` can properly
+  // resolve the default "typescript" module when the project doesn't include
+  // its own version. To properly test for this, a fixture needs to be created
+  // *outside* of the `vercel` repo, since otherwise the root-level
+  // "node_modules/typescript" is resolved as relative to the project, and
+  // not relative to `@vercel/node` which is what we are testing for here.
+  const dir = join(os.tmpdir(), 'vercel-node-typescript-resolve-test');
+  const apiDir = join(dir, 'api');
+  await fs.mkdirp(apiDir);
+  await fs.writeFile(
+    join(apiDir, 'hello.js'),
+    'export default (req, res) => { res.end("world"); }'
+  );
+
+  const { dev, port, readyResolver } = await testFixture(dir);
+
+  try {
+    await readyResolver;
+
+    const res = await fetch(`http://localhost:${port}/api/hello`);
+    const body = await res.text();
+    t.is(body, 'world');
+  } finally {
+    await dev.kill('SIGTERM');
+    await fs.remove(dir);
+  }
 });
 
 test(
@@ -495,6 +666,7 @@ test(
   testFixtureStdio('public-and-api', async testPath => {
     await testPath(200, '/', 'This is the home page');
     await testPath(200, '/about.html', 'This is the about page');
+    await testPath(200, '/.well-known/humans.txt', 'We come in peace');
     await testPath(200, '/api/date', /current date/);
     await testPath(200, '/api/rand', /random number/);
     await testPath(200, '/api/rand.js', /random number/);
@@ -523,7 +695,7 @@ test('[vercel dev] validate builds', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `builds` property: \[0\]\.src should be string/m
+    /Invalid vercel\.json - `builds\[0\].src` should be string/m
   );
 });
 
@@ -534,7 +706,7 @@ test('[vercel dev] validate routes', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `routes` property: \[0\]\.src should be string/m
+    /Invalid vercel\.json - `routes\[0\].src` should be string/m
   );
 });
 
@@ -543,7 +715,10 @@ test('[vercel dev] validate cleanUrls', async t => {
   const output = await exec(directory);
 
   t.is(output.exitCode, 1, formatOutput(output));
-  t.regex(output.stderr, /Invalid `cleanUrls` property:\s+should be boolean/m);
+  t.regex(
+    output.stderr,
+    /Invalid vercel\.json - `cleanUrls` should be boolean/m
+  );
 });
 
 test('[vercel dev] validate trailingSlash', async t => {
@@ -553,7 +728,7 @@ test('[vercel dev] validate trailingSlash', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `trailingSlash` property:\s+should be boolean/m
+    /Invalid vercel\.json - `trailingSlash` should be boolean/m
   );
 });
 
@@ -564,7 +739,7 @@ test('[vercel dev] validate rewrites', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `rewrites` property: \[0\]\.destination should be string/m
+    /Invalid vercel\.json - `rewrites\[0\].destination` should be string/m
   );
 });
 
@@ -575,7 +750,7 @@ test('[vercel dev] validate redirects', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `redirects` property: \[0\]\.statusCode should be integer/m
+    /Invalid vercel\.json - `redirects\[0\].statusCode` should be integer/m
   );
 });
 
@@ -586,7 +761,7 @@ test('[vercel dev] validate headers', async t => {
   t.is(output.exitCode, 1, formatOutput(output));
   t.regex(
     output.stderr,
-    /Invalid `headers` property: \[0\]\.headers\[0\]\.value should be string/m
+    /Invalid vercel\.json - `headers\[0\].headers\[0\].value` should be string/m
   );
 });
 
@@ -836,11 +1011,26 @@ test(
   })
 );
 
+test(
+  '[vercel dev] support dynamic next.js routes in monorepos',
+  testFixtureStdio('monorepo-dynamic-paths', async testPath => {
+    await testPath(200, '/', /This is our homepage/m);
+    await testPath(200, '/about', /This is the about static page./m);
+    await testPath(
+      200,
+      '/1/dynamic',
+      /This is the (.*)dynamic(.*) page with static props./m
+    );
+  })
+);
+
 test(
   '[vercel dev] 00-list-directory',
   testFixtureStdio('00-list-directory', async testPath => {
     await testPath(200, '/', /Files within/m);
     await testPath(200, '/', /test[0-3]\.txt/m);
+    await testPath(200, '/', /\.well-known/m);
+    await testPath(200, '/.well-known/keybase.txt', 'proof goes here');
   })
 );
 
@@ -918,6 +1108,13 @@ test(
   '[vercel dev] 06-gridsome',
   testFixtureStdio('06-gridsome', async testPath => {
     await testPath(200, '/');
+    await testPath(200, '/about');
+    await testPath(308, '/support', 'Redirecting to /about?ref=support (308)', {
+      Location: '/about?ref=support',
+    });
+    // Bug with gridsome's dev server: https://github.com/gridsome/gridsome/issues/831
+    // Works in prod only so leave out for now
+    // await testPath(404, '/nothing');
   })
 );
 
@@ -925,6 +1122,9 @@ test(
   '[vercel dev] 07-hexo-node',
   testFixtureStdio('07-hexo-node', async testPath => {
     await testPath(200, '/', /Hexo \+ Node.js API/m);
+    await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
+    await testPath(200, '/contact.html', /Contact Us/m);
+    await testPath(200, '/support', /Contact Us/m);
   })
 );
 
@@ -949,6 +1149,8 @@ test(
   testFixtureStdio('10-nextjs-node', async testPath => {
     await testPath(200, '/', /Next.js \+ Node.js API/m);
     await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
+    await testPath(200, '/contact', /Contact Page/);
+    await testPath(200, '/support', /Contact Page/);
     await testPath(404, '/nothing', /Custom Next 404/);
   })
 );
@@ -959,6 +1161,7 @@ test(
     '12-polymer-node',
     async testPath => {
       await testPath(200, '/', /Polymer \+ Node.js API/m);
+      await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
     },
     { skipDeploy: true }
   )
@@ -970,6 +1173,7 @@ test(
     '13-preact-node',
     async testPath => {
       await testPath(200, '/', /Preact/m);
+      await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
     },
     { skipDeploy: true }
   )
@@ -981,6 +1185,7 @@ test(
     '14-svelte-node',
     async testPath => {
       await testPath(200, '/', /Svelte/m);
+      await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
     },
     { skipDeploy: true }
   )
@@ -992,6 +1197,7 @@ test(
     '16-vue-node',
     async testPath => {
       await testPath(200, '/', /Vue.js \+ Node.js API/m);
+      await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
     },
     { skipDeploy: true }
   )
@@ -1003,6 +1209,7 @@ test(
     '17-vuepress-node',
     async testPath => {
       await testPath(200, '/', /VuePress \+ Node.js API/m);
+      await testPath(200, '/api/date', new RegExp(new Date().getFullYear()));
     },
     { skipDeploy: true }
   )
@@ -1256,13 +1463,10 @@ test('[vercel dev] render warning for empty cwd dir', async t => {
 
     // Monitor `stderr` for the warning
     dev.stderr.setEncoding('utf8');
+    const msg = 'There are no files inside your deployment.';
     await new Promise(resolve => {
       dev.stderr.on('data', str => {
-        if (
-          str.includes(
-            'There are no files (or only files starting with a dot) inside your deployment'
-          )
-        ) {
+        if (str.includes(msg)) {
           resolve();
         }
       });
@@ -1401,6 +1605,23 @@ test(
   })
 );
 
+test(
+  '[vercel dev] Should force `tsc` option "module: commonjs" for `startDevServer()`',
+  testFixtureStdio('force-module-commonjs', async testPath => {
+    await testPath(200, `/`, /Force "module: commonjs" test page/);
+    await testPath(
+      200,
+      `/api`,
+      'Force "module: commonjs" JavaScript with ES Modules API endpoint'
+    );
+    await testPath(
+      200,
+      `/api/ts`,
+      'Force "module: commonjs" TypeScript API endpoint'
+    );
+  })
+);
+
 test(
   '[vercel dev] should prioritize index.html over other file named index.*',
   testFixtureStdio('index-html-priority', async testPath => {
@@ -1408,3 +1629,28 @@ test(
     await testPath(200, '/index.css', 'This is index.css');
   })
 );
+
+test(
+  '[vercel dev] Should support `*.go` API serverless functions',
+  testFixtureStdio('go', async testPath => {
+    await testPath(200, `/api`, 'This is the index page');
+    await testPath(200, `/api/index`, 'This is the index page');
+    await testPath(200, `/api/index.go`, 'This is the index page');
+    await testPath(200, `/api/another`, 'This is another page');
+    await testPath(200, '/api/another.go', 'This is another page');
+    await testPath(200, `/api/foo`, 'Req Path: /api/foo');
+    await testPath(200, `/api/bar`, 'Req Path: /api/bar');
+  })
+);
+
+test(
+  '[vercel dev] Should set the `ts-node` "target" to match Node.js version',
+  testFixtureStdio('node-ts-node-target', async testPath => {
+    await testPath(200, `/api/subclass`, '{"ok":true}');
+    await testPath(
+      200,
+      `/api/array`,
+      '{"months":[1,2,3,4,5,6,7,8,9,10,11,12]}'
+    );
+  })
+);

packages/now-cli/test/helpers/prepare.js

@@ -122,6 +122,7 @@ module.exports = async session => {
     'single-dotfile': {
       '.testing': 'i am a dotfile',
     },
+    'empty-directory': {},
     'config-scope-property-email': {
       'now.json': `{ "scope": "${session}@zeit.pub", "builds": [ { "src": "*.html", "use": "@now/static" } ], "version": 2 }`,
       'index.html': '<span>test scope email</span',
@@ -138,6 +139,10 @@ module.exports = async session => {
       'vercel.json': '{"fake": 1}',
       'index.html': '<h1>Fake</h1>',
     },
+    'builds-wrong-build-env': {
+      'vercel.json': '{ "build.env": { "key": "value" } }',
+      'index.html': '<h1>Should fail</h1>',
+    },
     'builds-no-list': {
       'now.json': `{
   "version": 2,
@@ -467,7 +472,7 @@ CMD ["node", "index.js"]`,
       'now.json': JSON.stringify({
         functions: {
           'api/**/*.php': {
-            runtime: 'now-php@0.0.8',
+            runtime: 'vercel-php@0.1.0',
           },
         },
       }),
@@ -478,7 +483,7 @@ CMD ["node", "index.js"]`,
         functions: {
           'api/**/*.php': {
             memory: 128,
-            runtime: 'now-php@canary',
+            runtime: 'vercel-php@canary',
           },
         },
       }),
@@ -496,12 +501,7 @@ CMD ["node", "index.js"]`,
       }),
     },
     'project-link': {
-      'pages/index.js': 'export default () => <div><h1>Now CLI test</h1></div>',
-      'package.json': JSON.stringify({
-        dependencies: {
-          gatsby: 'latest',
-        },
-      }),
+      'package.json': JSON.stringify({}),
     },
     'project-root-directory': {
       'src/index.html': '<h1>I am a website.</h1>',

packages/now-cli/test/integration.js

@@ -31,6 +31,8 @@ function execa(file, args, options) {
 
 const binaryPath = path.resolve(__dirname, `../scripts/start.js`);
 const fixture = name => path.join(__dirname, 'fixtures', 'integration', name);
+const example = name =>
+  path.join(__dirname, '..', '..', '..', 'examples', name);
 const deployHelpMessage = `${logo} vercel [options] <command | path>`;
 let session = 'temp-session';
 
@@ -243,8 +245,10 @@ test.after.always(async () => {
     loginApiServer.close();
   }
 
-  // Make sure the token gets revoked
-  await execa(binaryPath, ['logout', ...defaultArgs]);
+  // Make sure the token gets revoked unless it's passed in via environment
+  if (!process.env.VERCEL_TOKEN) {
+    await execa(binaryPath, ['logout', ...defaultArgs]);
+  }
 
   if (tmpDir) {
     // Remove config directory entirely
@@ -252,6 +256,20 @@ test.after.always(async () => {
   }
 });
 
+test('default command should prompt login with empty auth.json', async t => {
+  await fs.writeFile(getConfigAuthPath(), JSON.stringify({}));
+  try {
+    await execa(binaryPath, [...defaultArgs]);
+    t.fail();
+  } catch (err) {
+    t.true(
+      err.stderr.includes(
+        'Error! No existing credentials found. Please run `vercel login` or pass "--token"'
+      )
+    );
+  }
+});
+
 test('login', async t => {
   t.timeout(ms('1m'));
 
@@ -511,12 +529,46 @@ test('Deploy `api-env` fixture and test `vercel env` command', async t => {
     t.regex(stderr, /Created .env file/gm);
 
     const contents = fs.readFileSync(path.join(target, '.env'), 'utf8');
+    t.true(contents.startsWith('# Created by Vercel CLI\n'));
+
     const lines = new Set(contents.split('\n'));
     t.true(lines.has('MY_ENV_VAR="MY_VALUE"'));
     t.true(lines.has('MY_STDIN_VAR="{"expect":"quotes"}"'));
     t.true(lines.has('VERCEL_URL=""'));
   }
 
+  async function nowEnvPullOverwrite() {
+    const { exitCode, stderr, stdout } = await execa(
+      binaryPath,
+      ['env', 'pull', ...defaultArgs],
+      {
+        reject: false,
+        cwd: target,
+      }
+    );
+
+    t.is(exitCode, 0, formatOutput({ stderr, stdout }));
+    t.regex(stderr, /Overwriting existing .env file/gm);
+    t.regex(stderr, /Updated .env file/gm);
+  }
+
+  async function nowEnvPullConfirm() {
+    fs.writeFileSync(path.join(target, '.env'), 'hahaha');
+
+    const vc = execa(binaryPath, ['env', 'pull', ...defaultArgs], {
+      reject: false,
+      cwd: target,
+    });
+
+    await waitForPrompt(vc, chunk =>
+      chunk.includes('Found existing file ".env". Do you want to overwrite?')
+    );
+    vc.stdin.end('y\n');
+
+    const { exitCode, stderr, stdout } = await vc;
+    t.is(exitCode, 0, formatOutput({ stderr, stdout }));
+  }
+
   async function nowDeployWithVar() {
     const { exitCode, stderr, stdout } = await execa(
       binaryPath,
@@ -609,6 +661,8 @@ test('Deploy `api-env` fixture and test `vercel env` command', async t => {
   await nowEnvAddSystemEnv();
   await nowEnvLsIncludesVar();
   await nowEnvPull();
+  await nowEnvPullOverwrite();
+  await nowEnvPullConfirm();
   await nowDeployWithVar();
   await nowEnvRemove();
   await nowEnvRemoveWithArgs();
@@ -1304,7 +1358,7 @@ test('set platform version using `--platform-version` to `2`', async t => {
 });
 
 test('ensure we render a warning for deployments with no files', async t => {
-  const directory = fixture('single-dotfile');
+  const directory = fixture('empty-directory');
 
   const { stderr, stdout, exitCode } = await execa(
     binaryPath,
@@ -1327,11 +1381,7 @@ test('ensure we render a warning for deployments with no files', async t => {
   console.log(exitCode);
 
   // Ensure the warning is printed
-  t.true(
-    stderr.includes(
-      'There are no files (or only files starting with a dot) inside your deployment.'
-    )
-  );
+  t.regex(stderr, /There are no files inside your deployment/);
 
   // Test if the output is really a URL
   const { href, host } = new URL(stdout);
@@ -1341,10 +1391,8 @@ test('ensure we render a warning for deployments with no files', async t => {
   t.is(exitCode, 0);
 
   // Send a test request to the deployment
-  const response = await fetch(href);
-  const contentType = response.headers.get('content-type');
-
-  t.is(contentType, 'text/plain; charset=utf-8');
+  const res = await fetch(href);
+  t.is(res.status, 404);
 });
 
 test('ensure we render a prompt when deploying home directory', async t => {
@@ -1473,9 +1521,10 @@ test('try to create a builds deployments with wrong now.json', async t => {
   t.is(exitCode, 1);
   t.true(
     stderr.includes(
-      'Error! The property `builder` is not allowed in now.json – please remove it.'
+      'Error! Invalid now.json - should NOT have additional property `builder`. Did you mean `builds`?'
     )
   );
+  t.true(stderr.includes('https://vercel.com/docs/configuration'));
 });
 
 test('try to create a builds deployments with wrong vercel.json', async t => {
@@ -1496,9 +1545,35 @@ test('try to create a builds deployments with wrong vercel.json', async t => {
   t.is(exitCode, 1);
   t.true(
     stderr.includes(
-      'Error! The property `fake` is not allowed in vercel.json – please remove it.'
+      'Error! Invalid vercel.json - should NOT have additional property `fake`. Please remove it.'
     )
   );
+  t.true(stderr.includes('https://vercel.com/docs/configuration'));
+});
+
+test('try to create a builds deployments with wrong `build.env` property', async t => {
+  const directory = fixture('builds-wrong-build-env');
+
+  const { stderr, stdout, exitCode } = await execa(
+    binaryPath,
+    ['--public', ...defaultArgs, '--confirm'],
+    {
+      cwd: directory,
+      reject: false,
+    }
+  );
+
+  t.is(exitCode, 1, formatOutput({ stdout, stderr }));
+  t.true(
+    stderr.includes(
+      'Error! Invalid vercel.json - should NOT have additional property `build.env`. Did you mean `{ "build": { "env": {"name": "value"} } }`?'
+    ),
+    formatOutput({ stdout, stderr })
+  );
+  t.true(
+    stderr.includes('https://vercel.com/docs/configuration'),
+    formatOutput({ stdout, stderr })
+  );
 });
 
 test('create a builds deployments with no actual builds', async t => {
@@ -1589,7 +1664,7 @@ test('create a staging deployment', async t => {
     /Setting target to staging/gm,
     formatOutput(targetCall)
   );
-
+  t.regex(targetCall.stdout, /https:\/\//gm);
   t.is(targetCall.exitCode, 0, formatOutput(targetCall));
 
   const { host } = new URL(targetCall.stdout);
@@ -1625,6 +1700,7 @@ test('create a production deployment', async t => {
     /Setting target to production/gm,
     formatOutput(targetCall)
   );
+  t.regex(targetCall.stdout, /https:\/\//gm);
 
   const { host: targetHost } = new URL(targetCall.stdout);
   const targetDeployment = await apiFetch(
@@ -1648,6 +1724,7 @@ test('create a production deployment', async t => {
     /Setting target to production/gm,
     formatOutput(targetCall)
   );
+  t.regex(call.stdout, /https:\/\//gm);
 
   const { host } = new URL(call.stdout);
   const deployment = await apiFetch(
@@ -2341,7 +2418,7 @@ test('deploy a Lambda with a specific runtime', async t => {
   const { host: url } = new URL(output.stdout);
 
   const [build] = await getDeploymentBuildsByUrl(url);
-  t.is(build.use, 'now-php@0.0.8', JSON.stringify(build, null, 2));
+  t.is(build.use, 'vercel-php@0.1.0', JSON.stringify(build, null, 2));
 });
 
 test('fail to deploy a Lambda with a specific runtime but without a locked version', async t => {
@@ -2451,7 +2528,7 @@ test('should show prompts to set up project', async t => {
   await waitForPrompt(now, chunk =>
     chunk.includes(`What's your Development Command?`)
   );
-  now.stdin.write(`yarn dev\n`);
+  now.stdin.write(`\n`);
 
   await waitForPrompt(now, chunk => chunk.includes('Linked to'));
 
@@ -2482,6 +2559,41 @@ test('should show prompts to set up project', async t => {
   const response = await fetch(new URL(output.stdout).href);
   const text = await response.text();
   t.is(text.includes('<h1>custom hello</h1>'), true, text);
+
+  // Ensure that `vc dev` also uses the configured build command
+  // and output directory
+  let stderr = '';
+  const port = 58351;
+  const dev = execa(binaryPath, [
+    'dev',
+    '--listen',
+    port,
+    directory,
+    ...defaultArgs,
+  ]);
+  dev.stderr.setEncoding('utf8');
+
+  try {
+    dev.stdout.pipe(process.stdout);
+    dev.stderr.pipe(process.stderr);
+    await new Promise((resolve, reject) => {
+      dev.once('exit', (code, signal) => {
+        reject(`"vc dev" failed with ${signal || code}`);
+      });
+      dev.stderr.on('data', data => {
+        stderr += data;
+        if (stderr.includes('Ready! Available at')) {
+          resolve();
+        }
+      });
+    });
+
+    const res2 = await fetch(`http://localhost:${port}/`);
+    const text2 = await res2.text();
+    t.is(text2.includes('<h1>custom hello</h1>'), true, text2);
+  } finally {
+    process.kill(dev.pid, 'SIGTERM');
+  }
 });
 
 test('should prefill "project name" prompt with folder name', async t => {
@@ -2932,3 +3044,36 @@ test('`vc --debug project ls` should output the projects listing', async t => {
     formatOutput({ stderr, stdout })
   );
 });
+
+test('deploy gatsby twice and print cached directories', async t => {
+  const directory = example('gatsby');
+  const packageJsonPath = path.join(directory, 'package.json');
+  const packageJsonOriginal = await readFile(packageJsonPath, 'utf8');
+  const pkg = JSON.parse(packageJsonOriginal);
+
+  async function tryDeploy(cwd) {
+    await execa(binaryPath, [...defaultArgs, '--public', '--confirm'], {
+      cwd,
+      stdio: 'inherit',
+      reject: true,
+    });
+
+    t.true(true);
+  }
+
+  // Deploy once to populate the cache
+  await tryDeploy(directory);
+
+  // Wait because the cache is not available right away
+  // See https://codeburst.io/quick-explanation-of-the-s3-consistency-model-6c9f325e3f82
+  await sleep(60000);
+
+  // Update build script to ensure cached files were restored in the next deploy
+  pkg.scripts.build = `ls -lA && ls .cache && ls public && ${pkg.scripts.build}`;
+  await writeFile(packageJsonPath, JSON.stringify(pkg));
+  try {
+    await tryDeploy(directory);
+  } finally {
+    await writeFile(packageJsonPath, packageJsonOriginal);
+  }
+});

packages/now-client/.gitignore

@@ -3,4 +3,6 @@ lib
 node_modules
 *.log
 
-!tests/fixtures/nowignore/node_modules
+!tests/fixtures/nowignore/node_modules
+!tests/fixtures/vercelignore-allow-nodemodules/node_modules
+!tests/fixtures/vercelignore-allow-nodemodules/sub/node_modules

packages/now-client/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/client",
-  "version": "8.0.2-canary.2",
+  "version": "8.1.1-canary.1",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",
   "homepage": "https://vercel.com",

packages/now-client/src/check-deployment-status.ts

@@ -93,6 +93,16 @@ export async function* checkDeploymentStatus(
     }
 
     if (isAliasAssigned(deploymentUpdate)) {
+      if (
+        deploymentUpdate.aliasWarning &&
+        deploymentUpdate.aliasWarning.message
+      ) {
+        yield {
+          type: 'warning',
+          payload: deploymentUpdate.aliasWarning.message,
+        };
+      }
+
       debug('Deployment alias assigned');
       return yield { type: 'alias-assigned', payload: deploymentUpdate };
     }

packages/now-client/src/create-deployment.ts

@@ -1,6 +1,6 @@
 import { readdir as readRootFolder, lstatSync } from 'fs-extra';
 
-import { relative, isAbsolute, basename } from 'path';
+import { relative, isAbsolute } from 'path';
 import hashes, { mapToObject } from './utils/hashes';
 import { upload } from './upload';
 import { buildFileTree, createDebug, parseVercelConfig } from './utils';
@@ -139,17 +139,11 @@ export default function buildCreateDeployment(version: number) {
 
     // This is a useful warning because it prevents people
     // from getting confused about a deployment that renders 404.
-    if (
-      fileList.length === 0 ||
-      fileList.every(f => (f ? basename(f).startsWith('.') : true))
-    ) {
-      debug(
-        `Deployment path has no files (or only dotfiles). Yielding a warning event`
-      );
+    if (fileList.length === 0) {
+      debug('Deployment path has no files. Yielding a warning event');
       yield {
         type: 'warning',
-        payload:
-          'There are no files (or only files starting with a dot) inside your deployment.',
+        payload: 'There are no files inside your deployment.',
       };
     }
 

packages/now-client/src/types.ts

@@ -176,6 +176,7 @@ export interface DeploymentOptions extends LegacyDeploymentOptions {
   build?: {
     env: Dictionary<string>;
   };
+  source?: string;
   target?: string;
   name?: string;
   public?: boolean;

packages/now-client/src/utils/index.ts

@@ -7,6 +7,7 @@ import qs from 'querystring';
 import ignore from 'ignore';
 type Ignore = ReturnType<typeof ignore>;
 import { pkgVersion } from '../pkg';
+import { NowBuildError } from '@vercel/build-utils';
 import { NowClientOptions, DeploymentOptions, NowConfig } from '../types';
 import { Sema } from 'async-sema';
 import { readFile } from 'fs-extra';
@@ -48,7 +49,7 @@ export function getApiDeploymentsUrl(
     return '/v10/now/deployments';
   }
 
-  return '/v12/now/deployments';
+  return '/v13/now/deployments';
 }
 
 export async function parseVercelConfig(filePath?: string): Promise<NowConfig> {
@@ -76,43 +77,22 @@ const maybeRead = async function<T>(path: string, default_: T) {
   }
 };
 
-export async function readdirRelative(
-  path: string,
-  ignores: string[],
-  cwd: string
-): Promise<string[]> {
-  const preprocessedIgnores = ignores.map(ignore => {
-    if (ignore.endsWith('/')) {
-      return ignore.slice(0, -1);
-    }
-    return ignore;
-  });
-  const dirContents = await readdir(path, preprocessedIgnores);
-  return dirContents.map(filePath => relative(cwd, filePath));
-}
-
 export async function buildFileTree(
   path: string | string[],
   isDirectory: boolean,
   debug: Debug
 ): Promise<string[]> {
-  // Get .nowignore
-  let { ig, ignores } = await getVercelIgnore(path);
-
-  debug(`Found ${ig.ignores.length} rules in .nowignore`);
-
   let fileList: string[];
+  let { ig } = await getVercelIgnore(path);
 
+  debug(`Found ${ig.ignores.length} rules in .vercelignore`);
   debug('Building file tree...');
 
   if (isDirectory && !Array.isArray(path)) {
     // Directory path
     const cwd = process.cwd();
-    const relativeFileList = await readdirRelative(path, ignores, cwd);
-    fileList = ig
-      .filter(relativeFileList)
-      .map((relativePath: string) => join(cwd, relativePath));
-
+    const ignores = (absPath: string) => ig.ignores(relative(cwd, absPath));
+    fileList = await readdir(path, [ignores]);
     debug(`Read ${fileList.length} files in the specified directory`);
   } else if (Array.isArray(path)) {
     // Array of file paths
@@ -166,9 +146,12 @@ export async function getVercelIgnore(
         maybeRead(join(cwd, '.nowignore'), ''),
       ]);
       if (vercelignore && nowignore) {
-        throw new Error(
-          'Cannot use both a `.vercelignore` and `.nowignore` file. Please delete the `.nowignore` file.'
-        );
+        throw new NowBuildError({
+          code: 'CONFLICTING_IGNORE_FILES',
+          message:
+            'Cannot use both a `.vercelignore` and `.nowignore` file. Please delete the `.nowignore` file.',
+          link: 'https://vercel.link/combining-old-and-new-config',
+        });
       }
       return vercelignore || nowignore;
     })

packages/now-client/tests/fixtures/vercelignore-allow-nodemodules/.env.local

@@ -0,0 +1 @@
+EXCLUDE="this file should be ignored"

packages/now-client/tests/fixtures/vercelignore-allow-nodemodules/.vercelignore

@@ -0,0 +1,6 @@
+# literally dont ignore the node_modules directory
+# so basically include the node_modules directory recursively
+!node_modules/
+
+# ignore this file in addition to the defaults
+exclude.txt

packages/now-client/tests/fixtures/vercelignore-allow-nodemodules/exclude.txt

@@ -0,0 +1 @@
+Should be ignored

packages/now-client/tests/fixtures/vercelignore-allow-nodemodules/hello.txt

@@ -0,0 +1 @@
+Hello World

packages/now-client/tests/fixtures/vercelignore-allow-nodemodules/sub/include.txt

@@ -0,0 +1 @@
+Should be included

packages/now-client/tests/unit.utils.test.ts

@@ -1,7 +1,8 @@
-import path from 'path';
-import { buildFileTree, getVercelIgnore, readdirRelative } from '../src/utils';
+import { join, resolve } from 'path';
+import { buildFileTree } from '../src/utils';
 
-const ignoreFixturePath = path.resolve(__dirname, 'fixtures', 'nowignore');
+const fixture = (name: string) => resolve(__dirname, 'fixtures', name);
+const noop = () => {};
 
 const normalizeWindowsPaths = (files: string[]) => {
   if (process.platform === 'win32') {
@@ -10,34 +11,29 @@ const normalizeWindowsPaths = (files: string[]) => {
   return files;
 };
 
-describe('buildFileTree', () => {
-  it('will include the correct files', async () => {
-    const expected = [
-      'tests/fixtures/nowignore/.nowignore',
-      'tests/fixtures/nowignore/index.txt',
-    ].map(p => path.join(process.cwd(), p));
-    const actual = await buildFileTree(ignoreFixturePath, true, () => {});
-    expect(normalizeWindowsPaths(expected).sort()).toEqual(
-      normalizeWindowsPaths(actual).sort()
-    );
-  });
-});
+const toAbsolutePaths = (cwd: string, files: string[]) =>
+  files.map(p => join(cwd, p));
 
-describe('readdirRelative', () => {
-  it('will ignore the hardcoded default ignores', async () => {
-    // most importantly, this method should not walk/include node_modules
-    const expected = [
-      'tests/fixtures/nowignore/.nowignore',
-      'tests/fixtures/nowignore/ignore.txt',
-      'tests/fixtures/nowignore/index.txt',
-      'tests/fixtures/nowignore/folder/ignore.txt',
-    ];
-    const { ignores } = await getVercelIgnore(ignoreFixturePath);
-    const actual = await readdirRelative(
-      ignoreFixturePath,
-      ignores,
-      process.cwd()
+describe('buildFileTree', () => {
+  it('should exclude files using `.nowignore` blocklist', async () => {
+    const cwd = fixture('nowignore');
+    const expected = toAbsolutePaths(cwd, ['.nowignore', 'index.txt']);
+    const actual = await buildFileTree(cwd, true, noop);
+    expect(normalizeWindowsPaths(expected).sort()).toEqual(
+      normalizeWindowsPaths(actual).sort()
     );
+  });
+
+  it('should include the node_modules using `.vercelignore` allowlist', async () => {
+    const cwd = fixture('vercelignore-allow-nodemodules');
+    const expected = toAbsolutePaths(cwd, [
+      'node_modules/one.txt',
+      'sub/node_modules/two.txt',
+      'sub/include.txt',
+      '.vercelignore',
+      'hello.txt',
+    ]);
+    const actual = await buildFileTree(cwd, true, noop);
     expect(normalizeWindowsPaths(expected).sort()).toEqual(
       normalizeWindowsPaths(actual).sort()
     );

packages/now-go/build.sh

@@ -1,4 +1,13 @@
+#!/bin/bash
+set -euo pipefail
+
+# Start fresh
+rm -rf dist
+
+# Build with `ncc`
 ncc build index.ts -e @vercel/build-utils -e @now/build-utils -o dist
 ncc build install.ts -e @vercel/build-utils -e @now/build-utils -o dist/install
+
+# Move `install.js` to dist
 mv dist/install/index.js dist/install.js
 rm -rf dist/install

packages/now-go/dev-server.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"net"
+	"net/http"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// create a new handler
+	handler := http.HandlerFunc(__HANDLER_FUNC_NAME)
+
+	// https://stackoverflow.com/a/43425461/376773
+	listener, err := net.Listen("tcp", ":0")
+	if err != nil {
+		panic(err)
+	}
+
+	port := listener.Addr().(*net.TCPAddr).Port
+
+	file := os.NewFile(3, "pipe")
+	_, err2 := file.Write([]byte(strconv.Itoa(port)))
+	if err2 != nil {
+		panic(err2)
+	}
+
+	panic(http.Serve(listener, handler))
+}

packages/now-go/go-helpers.ts

@@ -3,7 +3,6 @@ import execa from 'execa';
 import fetch from 'node-fetch';
 import { mkdirp, pathExists } from 'fs-extra';
 import { dirname, join } from 'path';
-import { homedir } from 'os';
 import buildUtils from './build-utils';
 import stringArgv from 'string-argv';
 const { debug } = buildUtils;
@@ -127,50 +126,35 @@ export async function downloadGo(
   platform = process.platform,
   arch = process.arch
 ) {
-  // Check default `Go` in user machine
-  const isUserGo = await pathExists(join(homedir(), 'go'));
+  // Check if `go` is already installed in user's `$PATH`
+  const { failed, stdout } = await execa('go', ['version'], { reject: false });
 
-  // If we found GOPATH in ENV, or default `Go` path exists
-  // asssume that user have `Go` installed
-  if (isUserGo || process.env.GOPATH !== undefined) {
-    const { stdout } = await execa('go', ['version']);
-
-    if (parseInt(stdout.split('.')[1]) >= 11) {
-      return createGo(dir, platform, arch);
-    }
-
-    throw new Error(
-      `Your current ${stdout} doesn't support Go Modules. Please update.`
-    );
-  } else {
-    // Check `Go` bin in builder CWD
-    const isGoExist = await pathExists(join(dir, 'bin'));
-    if (!isGoExist) {
-      debug(
-        'Installing `go` v%s to %o for %s %s',
-        version,
-        dir,
-        platform,
-        arch
-      );
-      const url = getGoUrl(version, platform, arch);
-      debug('Downloading `go` URL: %o', url);
-      const res = await fetch(url);
-
-      if (!res.ok) {
-        throw new Error(`Failed to download: ${url} (${res.status})`);
-      }
-
-      // TODO: use a zip extractor when `ext === "zip"`
-      await mkdirp(dir);
-      await new Promise((resolve, reject) => {
-        res.body
-          .on('error', reject)
-          .pipe(tar.extract({ cwd: dir, strip: 1 }))
-          .on('error', reject)
-          .on('finish', resolve);
-      });
-    }
+  if (!failed && parseInt(stdout.split('.')[1]) >= 11) {
+    debug('Using system installed version of `go`: %o', stdout.trim());
     return createGo(dir, platform, arch);
   }
+
+  // Check `go` bin in builder CWD
+  const isGoExist = await pathExists(join(dir, 'bin'));
+  if (!isGoExist) {
+    debug('Installing `go` v%s to %o for %s %s', version, dir, platform, arch);
+    const url = getGoUrl(version, platform, arch);
+    debug('Downloading `go` URL: %o', url);
+    const res = await fetch(url);
+
+    if (!res.ok) {
+      throw new Error(`Failed to download: ${url} (${res.status})`);
+    }
+
+    // TODO: use a zip extractor when `ext === "zip"`
+    await mkdirp(dir);
+    await new Promise((resolve, reject) => {
+      res.body
+        .on('error', reject)
+        .pipe(tar.extract({ cwd: dir, strip: 1 }))
+        .on('error', reject)
+        .on('finish', resolve);
+    });
+  }
+  return createGo(dir, platform, arch);
 }

packages/now-go/index.ts

@@ -1,8 +1,24 @@
-import { join, sep, dirname, basename, normalize } from 'path';
-import { readFile, writeFile, pathExists, move } from 'fs-extra';
-import { homedir } from 'os';
 import execa from 'execa';
-import { BuildOptions, Meta, Files } from '@vercel/build-utils';
+import { homedir } from 'os';
+import { spawn } from 'child_process';
+import { Readable } from 'stream';
+import once from '@tootallnate/once';
+import { join, dirname, basename, normalize, sep } from 'path';
+import {
+  readFile,
+  writeFile,
+  pathExists,
+  mkdirp,
+  move,
+  remove,
+} from 'fs-extra';
+import {
+  BuildOptions,
+  Meta,
+  Files,
+  StartDevServerOptions,
+  StartDevServerResult,
+} from '@vercel/build-utils';
 import buildUtils from './build-utils';
 
 const {
@@ -17,6 +33,8 @@ const {
 import { createGo, getAnalyzedEntrypoint, OUT_EXTENSION } from './go-helpers';
 const handlerFileName = `handler${OUT_EXTENSION}`;
 
+export { shouldServe };
+
 interface Analyzed {
   found?: boolean;
   packageName: string;
@@ -24,16 +42,22 @@ interface Analyzed {
   watch: string[];
 }
 
+interface PortInfo {
+  port: number;
+}
+
 // Initialize private git repo for Go Modules
 async function initPrivateGit(credentials: string) {
+  const gitCredentialsPath = join(homedir(), '.git-credentials');
+
   await execa('git', [
     'config',
     '--global',
     'credential.helper',
-    `store --file ${join(homedir(), '.git-credentials')}`,
+    `store --file ${gitCredentialsPath}`,
   ]);
 
-  await writeFile(join(homedir(), '.git-credentials'), credentials);
+  await writeFile(gitCredentialsPath, credentials);
 }
 
 /**
@@ -436,4 +460,121 @@ Learn more: https://vercel.com/docs/runtimes#official-runtimes/go
   };
 }
 
-export { shouldServe };
+function isPortInfo(v: any): v is PortInfo {
+  return v && typeof v.port === 'number';
+}
+
+function isReadable(v: any): v is Readable {
+  return v && v.readable === true;
+}
+
+async function copyEntrypoint(entrypoint: string, dest: string): Promise<void> {
+  const data = await readFile(entrypoint, 'utf8');
+
+  // Modify package to `package main`
+  const patched = data.replace(/\bpackage\W+\S+\b/, 'package main');
+
+  await writeFile(join(dest, 'entrypoint.go'), patched);
+}
+
+async function copyDevServer(
+  functionName: string,
+  dest: string
+): Promise<void> {
+  const data = await readFile(join(__dirname, 'dev-server.go'), 'utf8');
+
+  // Populate the handler function name
+  const patched = data.replace('__HANDLER_FUNC_NAME', functionName);
+
+  await writeFile(join(dest, 'vercel-dev-server-main.go'), patched);
+}
+
+export async function startDevServer(
+  opts: StartDevServerOptions
+): Promise<StartDevServerResult> {
+  const { entrypoint, workPath, meta = {} } = opts;
+  const { devCacheDir = join(workPath, '.vercel', 'cache') } = meta;
+  const entrypointDir = dirname(entrypoint);
+
+  // For some reason, if `entrypoint` is a path segment (filename contains `[]`
+  // brackets) then the `.go` suffix on the entrypoint is missing. Fix that here…
+  let entrypointWithExt = entrypoint;
+  if (!entrypoint.endsWith('.go')) {
+    entrypointWithExt += '.go';
+  }
+
+  const tmp = join(
+    devCacheDir,
+    'go',
+    Math.random()
+      .toString(32)
+      .substring(2)
+  );
+  const tmpPackage = join(tmp, entrypointDir);
+  await mkdirp(tmpPackage);
+
+  let goModAbsPathDir = '';
+  if (await pathExists(join(workPath, 'go.mod'))) {
+    goModAbsPathDir = workPath;
+  }
+  const analyzedRaw = await getAnalyzedEntrypoint(
+    entrypointWithExt,
+    goModAbsPathDir
+  );
+  if (!analyzedRaw) {
+    throw new Error(
+      `Could not find an exported function in "${entrypointWithExt}"
+Learn more: https://vercel.com/docs/runtimes#official-runtimes/go`
+    );
+  }
+  const analyzed: Analyzed = JSON.parse(analyzedRaw);
+
+  await Promise.all([
+    copyEntrypoint(entrypointWithExt, tmpPackage),
+    copyDevServer(analyzed.functionName, tmpPackage),
+  ]);
+
+  const env: typeof process.env = {
+    ...process.env,
+    ...meta.env,
+  };
+
+  const tmpRelative = `.${sep}${entrypointDir}`;
+  const child = spawn('go', ['run', tmpRelative], {
+    cwd: tmp,
+    env,
+    stdio: ['ignore', 'inherit', 'inherit', 'pipe'],
+  });
+
+  child.once('exit', async () => {
+    await remove(tmp); // Cleanup
+  });
+
+  const portPipe = child.stdio[3];
+  if (!isReadable(portPipe)) {
+    throw new Error('File descriptor 3 is not readable');
+  }
+
+  // `dev-server.go` writes the ephemeral port number to FD 3 to be consumed here
+  const onPort = new Promise<PortInfo>(resolve => {
+    portPipe.setEncoding('utf8');
+    portPipe.once('data', d => {
+      resolve({ port: Number(d) });
+    });
+  });
+  const onExit = once.spread<[number, string | null]>(child, 'exit');
+  const result = await Promise.race([onPort, onExit]);
+  onExit.cancel();
+
+  if (isPortInfo(result)) {
+    return {
+      port: result.port,
+      pid: child.pid,
+    };
+  } else {
+    // Got "exit" event from child process
+    throw new Error(
+      `Failed to start dev server for "${entrypointWithExt}" (code=${result[0]}, signal=${result[1]})`
+    );
+  }
+}

packages/now-go/main.go

@@ -1,8 +1,8 @@
 package main
 
 import (
-	"net/http"
 	vc "github.com/vercel/go-bridge/go/bridge"
+	"net/http"
 )
 
 func main() {

packages/now-go/main__mod__.go

@@ -1,12 +1,12 @@
 package main
 
 import (
-  "net/http"
-  "__NOW_HANDLER_PACKAGE_NAME"
+	"__NOW_HANDLER_PACKAGE_NAME"
+	"net/http"
 
-  vc "github.com/vercel/go-bridge/go/bridge"
+	vc "github.com/vercel/go-bridge/go/bridge"
 )
 
 func main() {
-  vc.Start(http.HandlerFunc(__NOW_HANDLER_FUNC_NAME))
+	vc.Start(http.HandlerFunc(__NOW_HANDLER_FUNC_NAME))
 }

packages/now-go/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/go",
-  "version": "1.1.2-canary.2",
+  "version": "1.1.3-canary.1",
   "license": "MIT",
   "main": "./dist/index",
   "homepage": "https://vercel.com/docs/runtimes#official-runtimes/go",
@@ -19,6 +19,7 @@
     "dist"
   ],
   "devDependencies": {
+    "@tootallnate/once": "1.1.2",
     "@types/execa": "^0.9.0",
     "@types/fs-extra": "^5.0.5",
     "@types/node-fetch": "^2.3.0",