Assign emulator ports and resolve hostnames upfront.

scripts/emulator-tests/functionsEmulator.spec.ts

@@ -10,13 +10,12 @@ import * as logform from "logform";
 
 import { EmulatedTriggerDefinition } from "../../src/emulator/functionsEmulatorShared";
 import { FunctionsEmulator } from "../../src/emulator/functionsEmulator";
-import { Emulators } from "../../src/emulator/types";
+import { EmulatorInfo, Emulators } from "../../src/emulator/types";
 import { FakeEmulator } from "../../src/test/emulators/fakeEmulator";
 import { TIMEOUT_LONG, TIMEOUT_MED, MODULE_ROOT } from "./fixtures";
 import { logger } from "../../src/logger";
 import * as registry from "../../src/emulator/registry";
 import * as secretManager from "../../src/gcp/secretManager";
-import { findAvailablePort } from "../../src/emulator/portUtils";
 
 if ((process.env.DEBUG || "").toLowerCase().includes("spec")) {
   const dropLogLevels = (info: logform.TransformableInfo) => info.message;
@@ -614,22 +613,20 @@ describe("FunctionsEmulator-Hub", function () {
   });
 
   describe("environment variables", () => {
-    const host = "127.0.0.1";
-    const startFakeEmulator = async (emulator: Emulators): Promise<number> => {
-      const port = await findAvailablePort(host, 4000);
-      const fake = new FakeEmulator(emulator, host, port);
+    const startFakeEmulator = async (emulator: Emulators): Promise<EmulatorInfo> => {
+      const fake = await FakeEmulator.create(emulator);
       await registry.EmulatorRegistry.start(fake);
-      return port;
+      return fake.getInfo();
     };
 
     afterEach(() => {
       return registry.EmulatorRegistry.stopAll();
     });
 
     it("should set env vars when the emulator is running", async () => {
-      const databasePort = await startFakeEmulator(Emulators.DATABASE);
-      const firestorePort = await startFakeEmulator(Emulators.FIRESTORE);
-      const authPort = await startFakeEmulator(Emulators.AUTH);
+      const database = await startFakeEmulator(Emulators.DATABASE);
+      const firestore = await startFakeEmulator(Emulators.FIRESTORE);
+      const auth = await startFakeEmulator(Emulators.AUTH);
 
       await useFunction(emu, "functionId", () => {
         return {
@@ -649,9 +646,9 @@ describe("FunctionsEmulator-Hub", function () {
         .get("/fake-project-id/us-central1/functionId")
         .expect(200)
         .then((res) => {
-          expect(res.body.databaseHost).to.eql(`${host}:${databasePort}`);
-          expect(res.body.firestoreHost).to.eql(`${host}:${firestorePort}`);
-          expect(res.body.authHost).to.eql(`${host}:${authPort}`);
+          expect(res.body.databaseHost).to.eql(`${database.host}:${database.port}`);
+          expect(res.body.firestoreHost).to.eql(`${firestore.host}:${firestore.port}`);
+          expect(res.body.authHost).to.eql(`${auth.host}:${auth.port}`);
         });
     }).timeout(TIMEOUT_MED);
 

src/emulator/ExpressBasedEmulator.ts

@@ -0,0 +1,121 @@
+import * as cors from "cors";
+import * as express from "express";
+import * as bodyParser from "body-parser";
+
+import * as utils from "../utils";
+import { Emulators, EmulatorInstance, EmulatorInfo, ListenSpec } from "./types";
+import { createServer } from "node:http";
+import { IPV4_UNSPECIFIED, IPV6_UNSPECIFIED } from "./dns";
+import { ListenOptions } from "node:net";
+
+export interface ExpressBasedEmulatorOptions {
+  listen: ListenSpec[];
+  noCors?: boolean;
+  noBodyParser?: boolean;
+}
+
+export abstract class ExpressBasedEmulator implements EmulatorInstance {
+  static PATH_EXPORT = "/_admin/export";
+  static PATH_DISABLE_FUNCTIONS = "/functions/disableBackgroundTriggers";
+  static PATH_ENABLE_FUNCTIONS = "/functions/enableBackgroundTriggers";
+  static PATH_EMULATORS = "/emulators";
+
+  private destroyers = new Set<() => Promise<void>>();
+
+  constructor(private options: ExpressBasedEmulatorOptions) {}
+
+  protected createExpressApp(): Promise<express.Express> {
+    const app = express();
+    if (!this.options.noCors) {
+      // Enable CORS for all APIs, all origins (reflected), and all headers (reflected).
+      // This is enabled by default since most emulators are cookieless.
+      app.use(cors({ origin: true }));
+
+      // Return access-control-allow-private-network heder if requested
+      // Enables accessing locahost when site is exposed via tunnel see https://github.com/firebase/firebase-tools/issues/4227
+      // Aligns with https://wicg.github.io/private-network-access/#headers
+      // Replace with cors option if adopted, see https://github.com/expressjs/cors/issues/236
+      app.use((req, res, next) => {
+        if (req.headers["access-control-request-private-network"]) {
+          res.setHeader("access-control-allow-private-network", "true");
+        }
+        next();
+      });
+    }
+    if (!this.options.noBodyParser) {
+      app.use(bodyParser.json()); // used in most emulators
+    }
+    app.set("json spaces", 2);
+
+    return Promise.resolve(app);
+  }
+
+  async start(): Promise<void> {
+    const app = await this.createExpressApp();
+
+    const promises = [];
+    const specs = this.options.listen;
+
+    const listenOptions: ListenOptions[] = [];
+
+    const dualStackPorts = new Set();
+    for (const spec of specs) {
+      if (spec.address === IPV6_UNSPECIFIED.address) {
+        if (specs.some((s) => s.port === spec.port && s.address === IPV4_UNSPECIFIED.address)) {
+          // We can use the default dual-stack behavior in Node.js to listen on
+          // the same port on both IPv4 and IPv6 unspecified addresses on most OSes.
+          // https://nodejs.org/api/net.html#serverlistenport-host-backlog-callback
+          listenOptions.push({
+            port: spec.port,
+            ipv6Only: false,
+          });
+          dualStackPorts.add(spec.port);
+        }
+      }
+    }
+    // Then add options for non-dual-stack addresses and ports.
+    for (const spec of specs) {
+      if (!dualStackPorts.has(spec.port)) {
+        listenOptions.push({
+          host: spec.address,
+          port: spec.port,
+          ipv6Only: spec.family === "IPv6",
+        });
+      }
+    }
+
+    for (const opt of listenOptions) {
+      promises.push(
+        new Promise((resolve, reject) => {
+          const server = createServer(app).listen(opt);
+          server.once("listening", resolve);
+          server.once("error", reject);
+          this.destroyers.add(utils.createDestroyer(server));
+        })
+      );
+    }
+  }
+
+  async connect(): Promise<void> {
+    // no-op
+  }
+
+  async stop(): Promise<void> {
+    const promises = [];
+    for (const destroyer of this.destroyers) {
+      promises.push(destroyer().then(() => this.destroyers.delete(destroyer)));
+    }
+    await Promise.all(promises);
+  }
+
+  getInfo(): EmulatorInfo {
+    return {
+      name: this.getName(),
+      listen: this.options.listen,
+      host: this.options.listen[0].address,
+      port: this.options.listen[0].port,
+    };
+  }
+
+  abstract getName(): Emulators;
+}