feat: add metadata and onError to edge functions (#5584)

* feat: add metadata and `onError` to edge functions

* refactor: move `getFeatureFlagsHeader` to separate file

* refactor: move `getInvocationMetadataHeader` function

---------

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

src/lib/edge-functions/bootstrap.mjs

@@ -1,5 +1,5 @@
 import { env } from 'process'
 
-const latestBootstrapURL = 'https://64109c4552d9020008b9dadc--edge.netlify.com/bootstrap/index-combined.ts'
+const latestBootstrapURL = 'https://6419767d9dc968000848742a--edge.netlify.com/bootstrap/index-combined.ts'
 
 export const getBootstrapURL = () => env.NETLIFY_EDGE_BOOTSTRAP || latestBootstrapURL

src/lib/edge-functions/headers.mjs

@@ -1,11 +1,36 @@
-const headers = {
+// @ts-check
+import { Buffer } from 'buffer'
+
+export const headers = {
+  FeatureFlags: 'x-nf-feature-flags',
   ForwardedHost: 'x-forwarded-host',
   Functions: 'x-nf-edge-functions',
+  InvocationMetadata: 'x-nf-edge-functions-metadata',
   Geo: 'x-nf-geo',
   Passthrough: 'x-nf-passthrough',
   IP: 'x-nf-client-connection-ip',
   Site: 'X-NF-Site-Info',
   DebugLogging: 'x-nf-debug-logging',
 }
 
-export default headers
+/**
+ * Takes an array of feature flags and produces a Base64-encoded JSON object
+ * that the bootstrap layer can understand.
+ *
+ * @param {Array<string>} featureFlags
+ * @returns {string}
+ */
+export const getFeatureFlagsHeader = (featureFlags) => {
+  const featureFlagsObject = featureFlags.reduce((acc, flagName) => ({ ...acc, [flagName]: true }), {})
+
+  return Buffer.from(JSON.stringify(featureFlagsObject)).toString('base64')
+}
+
+/**
+ * Takes the invocation metadata object and produces a Base64-encoded JSON
+ * object that the bootstrap layer can understand.
+ *
+ * @param {object} metadata
+ * @returns {string}
+ */
+export const getInvocationMetadataHeader = (metadata) => Buffer.from(JSON.stringify(metadata)).toString('base64')

src/lib/edge-functions/proxy.mjs

@@ -12,7 +12,7 @@ import { startSpinner, stopSpinner } from '../spinner.mjs'
 
 import { getBootstrapURL } from './bootstrap.mjs'
 import { DIST_IMPORT_MAP_PATH } from './consts.mjs'
-import headers from './headers.mjs'
+import { headers, getFeatureFlagsHeader, getInvocationMetadataHeader } from './headers.mjs'
 import { getInternalFunctions } from './internal.mjs'
 import { EdgeFunctionsRegistry } from './registry.mjs'
 
@@ -109,7 +109,7 @@ export const initializeProxy = async ({
     await registry.initialize()
 
     const url = new URL(req.url, `http://${LOCAL_HOST}:${mainPort}`)
-    const { functionNames, orphanedDeclarations } = registry.matchURLPath(url.pathname)
+    const { functionNames, invocationMetadata, orphanedDeclarations } = registry.matchURLPath(url.pathname)
 
     // If the request matches a config declaration for an Edge Function without
     // a matching function file, we warn the user.
@@ -129,11 +129,15 @@ export const initializeProxy = async ({
       return
     }
 
+    const featureFlags = ['edge_functions_bootstrap_failure_mode']
+
     req[headersSymbol] = {
-      [headers.Functions]: functionNames.join(','),
+      [headers.FeatureFlags]: getFeatureFlagsHeader(featureFlags),
       [headers.ForwardedHost]: `localhost:${passthroughPort}`,
-      [headers.Passthrough]: 'passthrough',
+      [headers.Functions]: functionNames.join(','),
+      [headers.InvocationMetadata]: getInvocationMetadataHeader(invocationMetadata),
       [headers.IP]: LOCAL_HOST,
+      [headers.Passthrough]: 'passthrough',
     }
 
     if (debug) {

src/lib/edge-functions/registry.mjs

@@ -268,6 +268,10 @@ export class EdgeFunctionsRegistry {
       functionConfig: this.declarationsFromSource,
       functions: this.functions,
     })
+    const invocationMetadata = {
+      function_config: manifest.function_config,
+      routes: manifest.routes.map((route) => ({ function: route.function, pattern: route.pattern })),
+    }
     const routes = [...manifest.routes, ...manifest.post_cache_routes].map((route) => ({
       ...route,
       pattern: new RegExp(route.pattern),
@@ -283,7 +287,7 @@ export class EdgeFunctionsRegistry {
       .map((route) => route.function)
     const orphanedDeclarations = this.matchURLPathAgainstOrphanedDeclarations(urlPath)
 
-    return { functionNames, orphanedDeclarations }
+    return { functionNames, invocationMetadata, orphanedDeclarations }
   }
 
   matchURLPathAgainstOrphanedDeclarations(urlPath) {

tests/integration/100.command.dev.test.cjs

@@ -225,9 +225,17 @@ test('Serves an Edge Function with a rewrite', async (t) => {
             edge_functions: 'netlify/edge-functions',
           },
           edge_functions: [
+            {
+              function: 'hello-legacy',
+              path: '/hello-legacy',
+            },
+            {
+              function: 'yell',
+              path: '/hello',
+            },
             {
               function: 'hello',
-              path: '/edge-function',
+              path: '/hello',
             },
           ],
         },
@@ -238,18 +246,36 @@ test('Serves an Edge Function with a rewrite', async (t) => {
           content: '<html>goodbye</html>',
         },
       ])
+      .withEdgeFunction({
+        handler: async (_, context) => {
+          const res = await context.next()
+          const text = await res.text()
+
+          return new Response(text.toUpperCase(), res)
+        },
+        name: 'yell',
+      })
       .withEdgeFunction({
         handler: (_, context) => context.rewrite('/goodbye'),
+        name: 'hello-legacy',
+      })
+      .withEdgeFunction({
+        handler: (req) => new URL('/goodbye', req.url),
         name: 'hello',
       })
 
     await builder.buildAsync()
 
     await withDevServer({ cwd: builder.directory }, async (server) => {
-      const response = await got(`${server.url}/edge-function`)
+      const response1 = await got(`${server.url}/hello-legacy`)
 
-      t.is(response.statusCode, 200)
-      t.is(response.body, '<html>goodbye</html>')
+      t.is(response1.statusCode, 200)
+      t.is(response1.body, '<html>goodbye</html>')
+
+      const response2 = await got(`${server.url}/hello`)
+
+      t.is(response2.statusCode, 200)
+      t.is(response2.body, '<HTML>GOODBYE</HTML>')
     })
   })
 })
@@ -467,6 +493,67 @@ test('Serves an Edge Function that streams the response', async (t) => {
   })
 })
 
+test('When an edge function fails, serves a fallback defined by its `on_error` mode', async (t) => {
+  await withSiteBuilder('site-with-edge-function-that-fails', async (builder) => {
+    const publicDir = 'public'
+    builder
+      .withNetlifyToml({
+        config: {
+          build: {
+            publish: publicDir,
+            edge_functions: 'netlify/edge-functions',
+          },
+        },
+      })
+      .withContentFiles([
+        {
+          path: path.join(publicDir, 'hello-1.html'),
+          content: '<html>hello from the origin</html>',
+        },
+      ])
+      .withContentFiles([
+        {
+          path: path.join(publicDir, 'error-page.html'),
+          content: '<html>uh-oh!</html>',
+        },
+      ])
+      .withEdgeFunction({
+        config: { onError: 'bypass', path: '/hello-1' },
+        handler: () => {
+          // eslint-disable-next-line no-undef
+          ermThisWillFail()
+
+          return new Response('I will never get here')
+        },
+        name: 'hello-1',
+      })
+      .withEdgeFunction({
+        config: { onError: '/error-page', path: '/hello-2' },
+        handler: () => {
+          // eslint-disable-next-line no-undef
+          ermThisWillFail()
+
+          return new Response('I will never get here')
+        },
+        name: 'hello-2',
+      })
+
+    await builder.buildAsync()
+
+    await withDevServer({ cwd: builder.directory }, async (server) => {
+      const response1 = await got(`${server.url}/hello-1`)
+
+      t.is(response1.statusCode, 200)
+      t.is(response1.body, '<html>hello from the origin</html>')
+
+      const response2 = await got(`${server.url}/hello-2`)
+
+      t.is(response2.statusCode, 200)
+      t.is(response2.body, '<html>uh-oh!</html>')
+    })
+  })
+})
+
 test('redirect with country cookie', async (t) => {
   await withSiteBuilder('site-with-country-cookie', async (builder) => {
     builder