[remix] Allow runtime to be defined from a parent route (#9473)

Make it so that the `export const config = { runtime }` value is "inherited" from a parent route, if it is defined.

For example, "edge" can be defined in `app/root.tsx`, and so all routes will use the Edge runtime by default, unless `"runtime": "nodejs"` is used more specifically in a route deeper in the route hierarchy.

packages/remix/src/build.ts

@@ -18,7 +18,7 @@ import {
   scanParentDirs,
   walkParentDirs,
 } from '@vercel/build-utils';
-import { getConfig } from '@vercel/static-config';
+import { getConfig, BaseFunctionConfig } from '@vercel/static-config';
 import { nodeFileTrace } from '@vercel/nft';
 import { readConfig, RemixConfig } from '@remix-run/dev/dist/config';
 import type {
@@ -33,6 +33,7 @@ import {
   findConfig,
   getPathFromRoute,
   getRegExpFromPath,
+  getRouteIterator,
   isLayoutRoute,
 } from './utils';
 
@@ -181,16 +182,17 @@ module.exports = config;`;
   const remixRoutes = Object.values(remixConfig.routes);
 
   // Figure out which pages should be edge functions
-  const edgePages = new Set<ConfigRoute>();
+  let hasEdgeRoute = false;
+  const staticConfigsMap = new Map<ConfigRoute, BaseFunctionConfig>();
   const project = new Project();
   for (const route of remixRoutes) {
     const routePath = join(remixConfig.appDirectory, route.file);
     const staticConfig = getConfig(project, routePath);
-    const isEdge =
-      staticConfig?.runtime === 'edge' ||
-      staticConfig?.runtime === 'experimental-edge';
-    if (isEdge) {
-      edgePages.add(route);
+    if (staticConfig) {
+      staticConfigsMap.set(route, staticConfig);
+    }
+    if (staticConfig?.runtime && isEdgeRuntime(staticConfig.runtime)) {
+      hasEdgeRoute = true;
     }
   }
 
@@ -212,7 +214,7 @@ module.exports = config;`;
       serverBuildPath,
       nodeVersion
     ),
-    edgePages.size > 0
+    hasEdgeRoute
       ? createRenderEdgeFunction(
           entrypointFsDirname,
           repoRootPath,
@@ -238,7 +240,16 @@ module.exports = config;`;
     if (isLayoutRoute(route.id, remixRoutes)) continue;
 
     const path = getPathFromRoute(route, remixConfig.routes);
-    const isEdge = edgePages.has(route);
+
+    let isEdge = false;
+    for (const currentRoute of getRouteIterator(route, remixConfig.routes)) {
+      const staticConfig = staticConfigsMap.get(currentRoute);
+      if (staticConfig?.runtime) {
+        isEdge = isEdgeRuntime(staticConfig.runtime);
+        break;
+      }
+    }
+
     const fn =
       isEdge && edgeFunction
         ? // `EdgeFunction` currently requires the "name" property to be set.
@@ -461,3 +472,7 @@ async function ensureResolvable(start: string, base: string, pkgName: string) {
     `Failed to resolve "${pkgName}". To fix this error, add "${pkgName}" to "dependencies" in your \`package.json\` file.`
   );
 }
+
+function isEdgeRuntime(runtime: string): boolean {
+  return runtime === 'edge' || runtime === 'experimental-edge';
+}

packages/remix/src/utils.ts

@@ -25,21 +25,27 @@ export function isLayoutRoute(
   return routes.some(r => r.parentId === routeId);
 }
 
+export function* getRouteIterator(route: ConfigRoute, routes: RouteManifest) {
+  let currentRoute: ConfigRoute = route;
+  do {
+    yield currentRoute;
+    if (currentRoute.parentId) {
+      currentRoute = routes[currentRoute.parentId];
+    } else {
+      break;
+    }
+  } while (currentRoute);
+}
+
 export function getPathFromRoute(
   route: ConfigRoute,
   routes: RouteManifest
 ): string {
-  let currentRoute: ConfigRoute | undefined = route;
   const pathParts: string[] = [];
-  do {
+  for (const currentRoute of getRouteIterator(route, routes)) {
     if (currentRoute.index) pathParts.push('index');
     if (currentRoute.path) pathParts.push(currentRoute.path);
-    if (currentRoute.parentId) {
-      currentRoute = routes[currentRoute.parentId];
-    } else {
-      currentRoute = undefined;
-    }
-  } while (currentRoute);
+  }
   const path = pathParts.reverse().join('/');
   return path;
 }