feat: add file-based function discovery mode

scripts/bin-test/sources/broken-syntax/index.js

@@ -0,0 +1,6 @@
+const functions = require("firebase-functions");
+
+// This will cause a syntax error
+exports.broken = functions.https.onRequest((request, response) => {
+  response.send("Hello from Firebase!"
+}); // Missing closing parenthesis

scripts/bin-test/sources/broken-syntax/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "broken-syntax"
+}

scripts/bin-test/test.ts

@@ -105,7 +105,13 @@ const BASE_STACK = {
 interface Testcase {
   name: string;
   modulePath: string;
-  expected: Record<string, any>;
+  expected: Record<string, unknown>;
+}
+
+interface DiscoveryResult {
+  success: boolean;
+  manifest?: Record<string, unknown>;
+  error?: string;
 }
 
 async function retryUntil(
@@ -134,102 +140,121 @@ async function retryUntil(
   await Promise.race([retry, timedOut]);
 }
 
-async function startBin(
-  tc: Testcase,
-  debug?: boolean
-): Promise<{ port: number; cleanup: () => Promise<void> }> {
+async function runHttpDiscovery(modulePath: string): Promise<DiscoveryResult> {
   const getPort = promisify(portfinder.getPort) as () => Promise<number>;
   const port = await getPort();
 
   const proc = subprocess.spawn("npx", ["firebase-functions"], {
-    cwd: path.resolve(tc.modulePath),
+    cwd: path.resolve(modulePath),
     env: {
       PATH: process.env.PATH,
-      GLCOUD_PROJECT: "test-project",
+      GCLOUD_PROJECT: "test-project",
       PORT: port.toString(),
       FUNCTIONS_CONTROL_API: "true",
     },
   });
-  if (!proc) {
-    throw new Error("Failed to start firebase functions");
-  }
-  proc.stdout?.on("data", (chunk: Buffer) => {
-    console.log(chunk.toString("utf8"));
-  });
-  proc.stderr?.on("data", (chunk: Buffer) => {
-    console.log(chunk.toString("utf8"));
-  });
 
-  await retryUntil(async () => {
-    try {
-      await fetch(`http://localhost:${port}/__/functions.yaml`);
-    } catch (e) {
-      if (e?.code === "ECONNREFUSED") {
-        return false;
+  try {
+    // Wait for server to be ready
+    await retryUntil(async () => {
+      try {
+        await fetch(`http://localhost:${port}/__/functions.yaml`);
+        return true;
+      } catch (e: unknown) {
+        const error = e as { code?: string };
+        if (error.code === "ECONNREFUSED") {
+          // This is an expected error during server startup, so we should retry.
+          return false;
+        }
+        // Any other error is unexpected and should fail the test immediately.
+        throw e;
       }
-      throw e;
+    }, TIMEOUT_L);
+
+    const res = await fetch(`http://localhost:${port}/__/functions.yaml`);
+    const body = await res.text();
+
+    if (res.status === 200) {
+      const manifest = yaml.load(body) as Record<string, unknown>;
+      return { success: true, manifest };
+    } else {
+      return { success: false, error: body };
     }
-    return true;
-  }, TIMEOUT_L);
+  } finally {
+    proc.kill(9);
+  }
+}
 
-  if (debug) {
-    proc.stdout?.on("data", (data: unknown) => {
-      console.log(`[${tc.name} stdout] ${data}`);
+async function runStdioDiscovery(modulePath: string): Promise<DiscoveryResult> {
+  return new Promise((resolve, reject) => {
+    const proc = subprocess.spawn("npx", ["firebase-functions"], {
+      cwd: path.resolve(modulePath),
+      env: {
+        PATH: process.env.PATH,
+        GCLOUD_PROJECT: "test-project",
+        FUNCTIONS_CONTROL_API: "true",
+        FUNCTIONS_DISCOVERY_MODE: "stdio",
+      },
     });
 
-    proc.stderr?.on("data", (data: unknown) => {
-      console.log(`[${tc.name} stderr] ${data}`);
+    let stderr = "";
+
+    proc.stderr?.on("data", (chunk: Buffer) => {
+      stderr += chunk.toString("utf8");
     });
-  }
 
-  return {
-    port,
-    cleanup: async () => {
-      process.kill(proc.pid, 9);
-      await retryUntil(async () => {
-        try {
-          process.kill(proc.pid, 0);
-        } catch {
-          // process.kill w/ signal 0 will throw an error if the pid no longer exists.
-          return Promise.resolve(true);
-        }
-        return Promise.resolve(false);
-      }, TIMEOUT_L);
-    },
-  };
-}
+    const timeoutId = setTimeout(() => {
+      proc.kill(9);
+      reject(new Error(`Stdio discovery timed out after ${TIMEOUT_M}ms`));
+    }, TIMEOUT_M);
 
-describe("functions.yaml", function () {
-  // eslint-disable-next-line @typescript-eslint/no-invalid-this
-  this.timeout(TIMEOUT_XL);
+    proc.on("close", () => {
+      clearTimeout(timeoutId);
+      const manifestMatch = stderr.match(/__FIREBASE_FUNCTIONS_MANIFEST__:([\s\S]+)/);
+      if (manifestMatch) {
+        const base64 = manifestMatch[1];
+        const manifestJson = Buffer.from(base64, "base64").toString("utf8");
+        const manifest = JSON.parse(manifestJson) as Record<string, unknown>;
+        resolve({ success: true, manifest });
+        return;
+      }
 
-  function runTests(tc: Testcase) {
-    let port: number;
-    let cleanup: () => Promise<void>;
+      const errorMatch = stderr.match(/__FIREBASE_FUNCTIONS_MANIFEST_ERROR__:([\s\S]+)/);
+      if (errorMatch) {
+        resolve({ success: false, error: errorMatch[1] });
+        return;
+      }
 
-    before(async () => {
-      const r = await startBin(tc);
-      port = r.port;
-      cleanup = r.cleanup;
+      resolve({ success: false, error: "No manifest or error found" });
     });
 
-    after(async () => {
-      await cleanup?.();
+    proc.on("error", (err) => {
+      clearTimeout(timeoutId);
+      reject(err);
     });
+  });
+}
 
-    it("functions.yaml returns expected Manifest", async function () {
+describe("functions.yaml", function () {
+  // eslint-disable-next-line @typescript-eslint/no-invalid-this
+  this.timeout(TIMEOUT_XL);
+
+  const discoveryMethods = [
+    { name: "http", fn: runHttpDiscovery },
+    { name: "stdio", fn: runStdioDiscovery },
+  ];
+
+  function runDiscoveryTests(
+    tc: Testcase,
+    discoveryFn: (path: string) => Promise<DiscoveryResult>
+  ) {
+    it("returns expected manifest", async function () {
       // eslint-disable-next-line @typescript-eslint/no-invalid-this
       this.timeout(TIMEOUT_M);
 
-      const res = await fetch(`http://localhost:${port}/__/functions.yaml`);
-      const text = await res.text();
-      let parsed: any;
-      try {
-        parsed = yaml.load(text);
-      } catch (err) {
-        throw new Error(`Failed to parse functions.yaml: ${err}`);
-      }
-      expect(parsed).to.be.deep.equal(tc.expected);
+      const result = await discoveryFn(tc.modulePath);
+      expect(result.success).to.be.true;
+      expect(result.manifest).to.deep.equal(tc.expected);
     });
   }
 
@@ -320,7 +345,11 @@ describe("functions.yaml", function () {
 
     for (const tc of testcases) {
       describe(tc.name, () => {
-        runTests(tc);
+        for (const discovery of discoveryMethods) {
+          describe(`${discovery.name} discovery`, () => {
+            runDiscoveryTests(tc, discovery.fn);
+          });
+        }
       });
     }
   });
@@ -350,7 +379,33 @@ describe("functions.yaml", function () {
 
     for (const tc of testcases) {
       describe(tc.name, () => {
-        runTests(tc);
+        for (const discovery of discoveryMethods) {
+          describe(`${discovery.name} discovery`, () => {
+            runDiscoveryTests(tc, discovery.fn);
+          });
+        }
+      });
+    }
+  });
+
+  describe("error handling", () => {
+    const errorTestcases = [
+      {
+        name: "broken syntax",
+        modulePath: "./scripts/bin-test/sources/broken-syntax",
+        expectedError: "missing ) after argument list",
+      },
+    ];
+
+    for (const tc of errorTestcases) {
+      describe(tc.name, () => {
+        for (const discovery of discoveryMethods) {
+          it(`${discovery.name} discovery handles error correctly`, async () => {
+            const result = await discovery.fn(tc.modulePath);
+            expect(result.success).to.be.false;
+            expect(result.error).to.include(tc.expectedError);
+          });
+        }
       });
     }
   });

src/bin/firebase-functions.ts

@@ -49,34 +49,62 @@ if (args.length > 1) {
   functionsDir = args[0];
 }
 
-let server: http.Server = undefined;
-const app = express();
+const MANIFEST_PREFIX = "__FIREBASE_FUNCTIONS_MANIFEST__:";
+const MANIFEST_ERROR_PREFIX = "__FIREBASE_FUNCTIONS_MANIFEST_ERROR__:";
 
-function handleQuitquitquit(req: express.Request, res: express.Response) {
+async function runStdioDiscovery() {
+  try {
+    const stack = await loadStack(functionsDir);
+    const wireFormat = stackToWire(stack);
+    const manifestJson = JSON.stringify(wireFormat);
+    const base64 = Buffer.from(manifestJson).toString("base64");
+    process.stderr.write(`${MANIFEST_PREFIX}${base64}\n`);
+    process.exitCode = 0;
+  } catch (e) {
+    console.error("Failed to generate manifest from function source:", e);
+    const message = e instanceof Error ? e.message : String(e);
+    process.stderr.write(`${MANIFEST_ERROR_PREFIX}${message}\n`);
+    process.exitCode = 1;
+  }
+}
+
+function handleQuitquitquit(req: express.Request, res: express.Response, server: http.Server) {
   res.send("ok");
   server.close();
 }
 
-app.get("/__/quitquitquit", handleQuitquitquit);
-app.post("/__/quitquitquit", handleQuitquitquit);
+if (
+  process.env.FUNCTIONS_CONTROL_API === "true" &&
+  process.env.FUNCTIONS_DISCOVERY_MODE === "stdio"
+) {
+  void runStdioDiscovery();
+} else {
+  let server: http.Server = undefined;
+  const app = express();
 
-if (process.env.FUNCTIONS_CONTROL_API === "true") {
-  app.get("/__/functions.yaml", async (req, res) => {
-    try {
-      const stack = await loadStack(functionsDir);
-      res.setHeader("content-type", "text/yaml");
-      res.send(JSON.stringify(stackToWire(stack)));
-    } catch (e) {
-      console.error(e);
-      res.status(400).send(`Failed to generate manifest from function source: ${e}`);
-    }
-  });
-}
+  app.get("/__/quitquitquit", (req, res) => handleQuitquitquit(req, res, server));
+  app.post("/__/quitquitquit", (req, res) => handleQuitquitquit(req, res, server));
 
-let port = 8080;
-if (process.env.PORT) {
-  port = Number.parseInt(process.env.PORT);
-}
+  if (process.env.FUNCTIONS_CONTROL_API === "true") {
+    // eslint-disable-next-line @typescript-eslint/no-misused-promises
+    app.get("/__/functions.yaml", async (req, res) => {
+      try {
+        const stack = await loadStack(functionsDir);
+        res.setHeader("content-type", "text/yaml");
+        res.send(JSON.stringify(stackToWire(stack)));
+      } catch (e) {
+        console.error(e);
+        const errorMessage = e instanceof Error ? e.message : String(e);
+        res.status(400).send(`Failed to generate manifest from function source: ${errorMessage}`);
+      }
+    });
+  }
+
+  let port = 8080;
+  if (process.env.PORT) {
+    port = Number.parseInt(process.env.PORT);
+  }
 
-console.log("Serving at port", port);
-server = app.listen(port);
+  console.log("Serving at port", port);
+  server = app.listen(port);
+}