feat: Add experimental support to discover functions via dynamic generation of functions.yaml (#8848)

taeold · web-flow · commit a02b9789b55d · 2025-07-16T22:24:37.000Z
Adds a new environment variable, FIREBASE_FUNCTIONS_DISCOVERY_OUTPUT_PATH, to enable an experimental file-based function discovery mechanism.

If FIREBASE_FUNCTIONS_DISCOVERY_OUTPUT_PATH=true, a temporary file path will be generated for the discovery manifest (functions.yaml).
If FIREBASE_FUNCTIONS_DISCOVERY_OUTPUT_PATH is set to a path, that path will be used to store the discovery manifest.
This change also includes a refactoring of the discovery codebase to use the modern fs/promises API instead of util.promisify.
diff --git a/.gitignore b/.gitignore
@@ -27,3 +27,4 @@ scripts/*.json
 lib/
 dev/
 clean/
+.gemini/
diff --git a/scripts/functions-discover-tests/fixtures/bundled/dist/package.json b/scripts/functions-discover-tests/fixtures/bundled/dist/package.json
@@ -1,7 +1,4 @@
 {
   "name": "dist",
-  "version": "0.0.1",
-  "engines": {
-    "node": "20"
-  }
+  "version": "0.0.1"
 }
diff --git a/scripts/functions-discover-tests/fixtures/bundled/firebase.json b/scripts/functions-discover-tests/fixtures/bundled/firebase.json
@@ -1,5 +1,6 @@
 {
   "functions": {
-    "source": "dist"
+    "source": "dist",
+    "runtime": "nodejs22"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/bundled/package.json b/scripts/functions-discover-tests/fixtures/bundled/package.json
@@ -2,9 +2,6 @@
   "name": "dist",
   "version": "0.0.1",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/codebases/firebase.json b/scripts/functions-discover-tests/fixtures/codebases/firebase.json
@@ -3,6 +3,7 @@
     {
       "source": "v1",
       "codebase": "v1",
+      "runtime": "nodejs22",
       "ignore": [
         "node_modules",
         ".git",
@@ -13,6 +14,7 @@
     {
       "source": "v2",
       "codebase": "v2",
+      "runtime": "nodejs22",
       "ignore": [
         "node_modules",
         ".git",
diff --git a/scripts/functions-discover-tests/fixtures/codebases/v1/package.json b/scripts/functions-discover-tests/fixtures/codebases/v1/package.json
@@ -1,9 +1,6 @@
 {
   "name": "codebase-v1",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/codebases/v2/package.json b/scripts/functions-discover-tests/fixtures/codebases/v2/package.json
@@ -2,9 +2,6 @@
   "name": "codebase-v2",
   "type": "module",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/esm/firebase.json b/scripts/functions-discover-tests/fixtures/esm/firebase.json
@@ -1,3 +1,6 @@
 {
-  "functions": {}
+  "functions": {
+    "source": "functions",
+    "runtime": "nodejs22"
+  }
 }
diff --git a/scripts/functions-discover-tests/fixtures/esm/functions/package.json b/scripts/functions-discover-tests/fixtures/esm/functions/package.json
@@ -2,9 +2,6 @@
   "name": "esm",
   "type": "module",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/pnpm/firebase.json b/scripts/functions-discover-tests/fixtures/pnpm/firebase.json
@@ -1,3 +1,6 @@
 {
-  "functions": {}
+  "functions": {
+    "source": "functions",
+    "runtime": "nodejs22"
+  }
 }
diff --git a/scripts/functions-discover-tests/fixtures/pnpm/functions/package.json b/scripts/functions-discover-tests/fixtures/pnpm/functions/package.json
@@ -1,9 +1,6 @@
 {
   "name": "pnpm",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/simple/firebase.json b/scripts/functions-discover-tests/fixtures/simple/firebase.json
@@ -1,3 +1,6 @@
 {
-  "functions": {}
+  "functions": {
+    "source": "functions",
+    "runtime": "nodejs22"
+  }
 }
diff --git a/scripts/functions-discover-tests/fixtures/simple/functions/package.json b/scripts/functions-discover-tests/fixtures/simple/functions/package.json
@@ -1,9 +1,6 @@
 {
   "name": "simple",
   "dependencies": {
-    "firebase-functions": "^5.1.0"
-  },
-  "engines": {
-    "node": "20"
+    "firebase-functions": "^6.4.0"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/stress-test/firebase.json b/scripts/functions-discover-tests/fixtures/stress-test/firebase.json
@@ -0,0 +1,6 @@
+{
+  "functions": {
+    "source": "functions",
+    "runtime": "nodejs22"
+  }
+}
diff --git a/scripts/functions-discover-tests/fixtures/stress-test/functions/index.js b/scripts/functions-discover-tests/fixtures/stress-test/functions/index.js
@@ -0,0 +1,8 @@
+const { onRequest } = require("firebase-functions/v2/https");
+
+// Generate 20 functions for stress testing
+for (let i = 1; i <= 20; i++) {
+  exports[`stressFunction${i}`] = onRequest((request, response) => {
+    response.send(`Hello from stress function ${i}!`);
+  });
+}
diff --git a/scripts/functions-discover-tests/fixtures/stress-test/functions/package.json b/scripts/functions-discover-tests/fixtures/stress-test/functions/package.json
@@ -0,0 +1,6 @@
+{
+  "name": "stress-test",
+  "dependencies": {
+    "firebase-functions": "^6.4.0"
+  }
+}
diff --git a/scripts/functions-discover-tests/fixtures/stress-test/install.sh b/scripts/functions-discover-tests/fixtures/stress-test/install.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+set -euxo pipefail # bash strict mode
+IFS=$'\n\t'
+
+cd functions && npm i
diff --git a/scripts/functions-discover-tests/fixtures/yarn-workspaces/firebase.json b/scripts/functions-discover-tests/fixtures/yarn-workspaces/firebase.json
@@ -1,5 +1,6 @@
 {
   "functions": {
-    "source": "packages/functions"
+    "source": "packages/functions",
+    "runtime": "nodejs22"
   }
 }
diff --git a/scripts/functions-discover-tests/fixtures/yarn-workspaces/packages/functions/package.json b/scripts/functions-discover-tests/fixtures/yarn-workspaces/packages/functions/package.json
@@ -2,12 +2,12 @@
   "name": "simple",
   "version": "0.0.1",
   "dependencies": {
-    "firebase-functions": "5.1.0",
+    "firebase-functions": "^6.4.0",
     "firebase-admin": "^11.2.0",
     "@firebase/a-test-pkg": "0.0.1"
   },
   "engines": {
-    "node": "20"
+    "node": ">=20"
   },
   "private": true
 }
diff --git a/scripts/functions-discover-tests/tests.ts b/scripts/functions-discover-tests/tests.ts
@@ -1,4 +1,6 @@
-import * as path from "path";
+import * as path from "node:path";
+import * as os from "node:os";
+import * as fs from "node:fs/promises";
 
 import { expect } from "chai";
 import { CLIProcess } from "../integration-helpers/cli";
@@ -15,8 +17,45 @@ interface Testcase {
   }[];
 }
 
+async function runDiscoveryTest(
+  projectDir: string,
+  testcase: Testcase,
+  env?: Record<string, string>,
+): Promise<void> {
+  const cli = new CLIProcess("default", projectDir);
+
+  let outputBuffer = "";
+  let output: any;
+  await cli.start(
+    "internaltesting:functions:discover",
+    FIREBASE_PROJECT,
+    ["--json"],
+    (data: any) => {
+      outputBuffer += data;
+      try {
+        output = JSON.parse(outputBuffer);
+        return true;
+      } catch (e) {
+        // Not complete JSON yet, continue buffering
+        return false;
+      }
+    },
+    env,
+  );
+
+  expect(output.status).to.equal("success");
+  for (const e of testcase.expects) {
+    const endpoints = output.result?.[e.codebase]?.endpoints;
+    expect(endpoints).to.be.an("object").that.is.not.empty;
+    expect(Object.keys(endpoints)).to.have.length(e.endpoints.length);
+    expect(Object.keys(endpoints)).to.include.members(e.endpoints);
+  }
+
+  await cli.stop();
+}
+
 describe("Function discovery test", function (this) {
-  this.timeout(1000_000);
+  this.timeout(2000_000);
 
   before(() => {
     expect(FIREBASE_PROJECT).to.exist.and.not.be.empty;
@@ -87,31 +126,41 @@ describe("Function discovery test", function (this) {
         },
       ],
     },
+    {
+      name: "stress-test",
+      projectDir: "stress-test",
+      expects: [
+        {
+          codebase: "default",
+          endpoints: Array.from({ length: 20 }, (_, i) => `stressFunction${i + 1}`),
+        },
+      ],
+    },
   ];
 
-  for (const tc of testCases) {
-    it(`discovers functions in a ${tc.name} project`, async () => {
-      const cli = new CLIProcess("default", path.join(FIXTURES, tc.projectDir));
-
-      let output: any;
-      await cli.start(
-        "internaltesting:functions:discover",
-        FIREBASE_PROJECT,
-        ["--json"],
-        (data: any) => {
-          output = JSON.parse(data);
-          return true;
-        },
-      );
-      expect(output.status).to.equal("success");
-      for (const e of tc.expects) {
-        const endpoints = output.result?.[e.codebase]?.endpoints;
-        expect(endpoints).to.be.an("object").that.is.not.empty;
-        expect(Object.keys(endpoints)).to.have.length(e.endpoints.length);
-        expect(Object.keys(endpoints)).to.include.members(e.endpoints);
-      }
+  describe("detectFromPort", () => {
+    for (const tc of testCases) {
+      it(`discovers functions using HTTP in a ${tc.name} project`, async () => {
+        await runDiscoveryTest(path.join(FIXTURES, tc.projectDir), tc);
+      });
+    }
+  });
 
-      await cli.stop();
-    });
-  }
+  describe("detectFromOutputPath", () => {
+    for (const tc of testCases) {
+      it(`discovers functions using file-based discovery in a ${tc.name} project`, async () => {
+        const tempDir = await fs.mkdtemp(path.join(os.tmpdir(), "firebase-test-"));
+        try {
+          await runDiscoveryTest(path.join(FIXTURES, tc.projectDir), tc, {
+            FIREBASE_FUNCTIONS_DISCOVERY_OUTPUT_PATH: tempDir,
+          });
+        } finally {
+          // Clean up the temp directory
+          await fs.rm(tempDir, { recursive: true, force: true }).catch(() => {
+            // Ignore cleanup errors
+          });
+        }
+      });
+    }
+  });
 });
diff --git a/scripts/integration-helpers/cli.ts b/scripts/integration-helpers/cli.ts
@@ -14,14 +14,18 @@ export class CLIProcess {
     project: string,
     additionalArgs: string[],
     logDoneFn?: (d: unknown) => unknown,
+    env?: Record<string, string>,
   ): Promise<void> {
     const args = [cmd, "--project", project];
 
     if (additionalArgs) {
       args.push(...additionalArgs);
     }
 
-    const p = spawn("firebase", args, { cwd: this.workdir });
+    const p = spawn("firebase", args, {
+      cwd: this.workdir,
+      env: env ? { ...process.env, ...env } : process.env,
+    });
     if (!p) {
       throw new Error("Failed to start firebase CLI");
     }
@@ -51,6 +55,9 @@ export class CLIProcess {
         };
         p.stdout?.on("data", customCallback);
         p.stdout?.on("close", customFailure);
+        p.stderr?.on("data", (data) => {
+          console.error(`[${this.name} stderr]`, data.toString());
+        });
       });
     } else {
       started = new Promise((resolve) => {
diff --git a/src/deploy/functions/runtimes/discovery/index.spec.ts b/src/deploy/functions/runtimes/discovery/index.spec.ts
@@ -1,4 +1,5 @@
 import { expect } from "chai";
+import * as fs from "fs/promises";
 import * as yaml from "yaml";
 import * as sinon from "sinon";
 import * as nock from "nock";
@@ -63,26 +64,26 @@ describe("yamlToBuild", () => {
 });
 
 describe("detectFromYaml", () => {
-  let readFileAsync: sinon.SinonStub;
+  let readFile: sinon.SinonStub;
 
   beforeEach(() => {
-    readFileAsync = sinon.stub(discovery, "readFileAsync");
+    readFile = sinon.stub(fs, "readFile");
   });
 
   afterEach(() => {
     sinon.verifyAndRestore();
   });
 
   it("succeeds when YAML can be found", async () => {
-    readFileAsync.resolves(YAML_TEXT);
+    readFile.resolves(YAML_TEXT);
 
     await expect(
       discovery.detectFromYaml("directory", "project", "nodejs16"),
     ).to.eventually.deep.equal(BUILD);
   });
 
   it("returns undefined when YAML cannot be found", async () => {
-    readFileAsync.rejects({ code: "ENOENT" });
+    readFile.rejects({ code: "ENOENT" });
 
     await expect(discovery.detectFromYaml("directory", "project", "nodejs16")).to.eventually.equal(
       undefined,
diff --git a/src/deploy/functions/runtimes/discovery/index.ts b/src/deploy/functions/runtimes/discovery/index.ts
diff --git a/src/deploy/functions/runtimes/node/index.ts b/src/deploy/functions/runtimes/node/index.ts

-Original file line number
+Diff line change
 lib/
 dev/
 clean/
 +.gemini/
Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,4 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "dist",`
`3`		`- "version": "0.0.1",`
`4`		`- "engines": {`
`5`		`- "node": "20"`
`6`		`- }`
	`3`	`+ "version": "0.0.1"`
`7`	`4`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"functions": {`
`3`		`- "source": "dist"`
	`3`	`+ "source": "dist",`
	`4`	`+ "runtime": "nodejs22"`
`4`	`5`	`}`
`5`	`6`	`}`
Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,6 @@`
`2`	`2`	`"name": "dist",`
`3`	`3`	`"version": "0.0.1",`
`4`	`4`	`"dependencies": {`
`5`		`- "firebase-functions": "^5.1.0"`
`6`		`- },`
`7`		`- "engines": {`
`8`		`- "node": "20"`
	`5`	`+ "firebase-functions": "^6.4.0"`
`9`	`6`	`}`
`10`	`7`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,9 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "codebase-v1",`
`3`	`3`	`"dependencies": {`
`4`		`- "firebase-functions": "^5.1.0"`
`5`		`- },`
`6`		`- "engines": {`
`7`		`- "node": "20"`
	`4`	`+ "firebase-functions": "^6.4.0"`
`8`	`5`	`}`
`9`	`6`	`}`
Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,6 @@`
`2`	`2`	`"name": "codebase-v2",`
`3`	`3`	`"type": "module",`
`4`	`4`	`"dependencies": {`
`5`		`- "firebase-functions": "^5.1.0"`
`6`		`- },`
`7`		`- "engines": {`
`8`		`- "node": "20"`
	`5`	`+ "firebase-functions": "^6.4.0"`
`9`	`6`	`}`
`10`	`7`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,6 @@`
`1`	`1`	`{`
`2`		`- "functions": {}`
	`2`	`+ "functions": {`
	`3`	`+ "source": "functions",`
	`4`	`+ "runtime": "nodejs22"`
	`5`	`+ }`
`3`	`6`	`}`
Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,6 @@`
`2`	`2`	`"name": "esm",`
`3`	`3`	`"type": "module",`
`4`	`4`	`"dependencies": {`
`5`		`- "firebase-functions": "^5.1.0"`
`6`		`- },`
`7`		`- "engines": {`
`8`		`- "node": "20"`
	`5`	`+ "firebase-functions": "^6.4.0"`
`9`	`6`	`}`
`10`	`7`	`}`