Adding support for <product>_EMULATOR_BINARY_PATH for local emualtor dev

src/emulator/download.ts

@@ -12,8 +12,16 @@
 
 tmp.setGracefulCleanup();
 
 export async function downloadEmulator(name: DownloadableEmulators): Promise<void> {
   const emulator = downloadableEmulators.getDownloadDetails(name);
+  if (emulator.localOnly) {
+    EmulatorLogger.forEmulator(name).logLabeled(
+      "WARN",
+      name,
+      `Env variable override detected, skipping download. Using ${emulator} emulator at ${emulator.binaryPath}`,
+    );
+    return;
+  }
   EmulatorLogger.forEmulator(name).logLabeled(
     "BULLET",
     name,
@@ -43,7 +51,7 @@
   removeOldFiles(name, emulator);
 }
 
 export async function downloadExtensionVersion(
   extensionVersionRef: string,
   sourceDownloadUri: string,
   targetDir: string,
@@ -86,7 +94,7 @@
   for (const file of files) {
     const fullFilePath = path.join(emulator.opts.cacheDir, file);
 
     if (file.indexOf(emulator.opts.namePrefix) < 0) {
       // This file is not related to this emulator, could be a JAR
       // from a different emulator or just a random file.
       continue;
@@ -130,7 +138,7 @@
   return new Promise((resolve, reject) => {
     const hash = crypto.createHash("md5");
     const stream = fs.createReadStream(filepath);
     stream.on("data", (data: any) => hash.update(data));
     stream.on("end", () => {
       const checksum = hash.digest("hex");
       return checksum === expectedChecksum

src/emulator/downloadableEmulators.ts

@@ -265,7 +265,7 @@
     shell: false,
   },
   pubsub: {
     binary: getExecPath(Emulators.PUBSUB)!,
     args: [],
     optionalArgs: ["port", "host"],
     joinArgs: true,
@@ -293,7 +293,7 @@
 }
 
 /**
  * @param name
  */
 export function getLogFileName(name: string): string {
   return `${name}-debug.log`;
@@ -306,7 +306,7 @@
  */
 export function _getCommand(
   emulator: DownloadableEmulators,
   args: { [s: string]: any },
 ): DownloadableEmulatorCommand {
   const baseCmd = Commands[emulator];
 
@@ -489,7 +489,21 @@
  * @param emulator
  */
 export function getDownloadDetails(emulator: DownloadableEmulators): EmulatorDownloadDetails {
-  return DownloadDetails[emulator];
+  const details = DownloadDetails[emulator];
+  const pathOverride = process.env[`${emulator.toUpperCase()}_EMULATOR_BINARY_PATH`];
+  if (pathOverride) {
+    const logger = EmulatorLogger.forEmulator(emulator);
+    logger.logLabeled(
+      "WARN",
+      emulator,
+      `Env variable override detected. Using ${emulator} emulator at ${pathOverride}`,
+    );
+    details.downloadPath = pathOverride;
+    details.binaryPath = pathOverride;
+    details.localOnly = true;
+    fs.chmodSync(pathOverride, 0o755);
+  }
+  return details;
 }
 
 /**
@@ -565,7 +579,7 @@
   },
   extraEnv: Partial<NodeJS.ProcessEnv> = {},
 ): Promise<void> {
-  const downloadDetails = DownloadDetails[targetName];
+  const downloadDetails = getDownloadDetails(targetName);
   const emulator = get(targetName);
   const hasEmulator = fs.existsSync(getExecPath(targetName));
   const logger = EmulatorLogger.forEmulator(targetName);

src/emulator/storage/rules/runtime.ts

@@ -27,7 +27,7 @@ import { downloadEmulator } from "../../download";
 import * as fs from "fs-extra";
 import {
   _getCommand,
-  DownloadDetails,
+  getDownloadDetails,
   handleEmulatorProcessError,
 } from "../../downloadableEmulators";
 import { EmulatorRegistry } from "../../registry";
@@ -124,7 +124,7 @@ export class StorageRulesRuntime {
     if (this.alive) {
       return;
     }
-    const downloadDetails = DownloadDetails[Emulators.STORAGE];
+    const downloadDetails = getDownloadDetails(Emulators.STORAGE);
     const hasEmulator = fs.existsSync(downloadDetails.downloadPath);
 
     if (!hasEmulator) {

src/emulator/types.ts

@@ -190,6 +190,9 @@ export interface EmulatorDownloadDetails {
   // If specified, a path where the runnable binary can be found after downloading and
   // unzipping. Otherwise downloadPath will be used.
   binaryPath?: string;
+
+  // If true, never try to download this emualtor. Set when developing with local versions of an emulator.
+  localOnly?: boolean;
 }
 
 export interface DownloadableEmulatorDetails {

src/test/emulators/downloadableEmulators.spec.ts

@@ -1,5 +1,7 @@
 import { expect } from "chai";
 import * as path from "path";
+import * as sinon from "sinon";
+import * as fs from "fs-extra";
 
 import * as downloadableEmulators from "../../emulator/downloadableEmulators";
 import { Emulators } from "../../emulator/types";
@@ -12,9 +14,48 @@ function checkDownloadPath(name: DownloadableEmulator): void {
 }
 
 describe("downloadDetails", () => {
+  const tempEnvVars: Record<DownloadableEmulator, string> = {
+    firestore: "",
+    database: "",
+    pubsub: "",
+  };
+  let chmodStub: sinon.SinonStub;
+  beforeEach(() => {
+    chmodStub = sinon.stub(fs, "chmodSync").returns();
+    tempEnvVars["firestore"] = process.env["FIRESTORE_EMULATOR_BINARY_PATH"] ?? "";
+    tempEnvVars["database"] = process.env["DATABASE_EMULATOR_BINARY_PATH"] ?? "";
+    tempEnvVars["pubsub"] = process.env["PUBSUB_EMULATOR_BINARY_PATH"] ?? "";
+    delete process.env["FIRESTORE_EMULATOR_BINARY_PATH"];
+    delete process.env["DATABASE_EMULATOR_BINARY_PATH"];
+    delete process.env["PUBSUB_EMULATOR_BINARY_PATH"];
+  });
+
+  afterEach(() => {
+    chmodStub.restore();
+    process.env["FIRESTORE_EMULATOR_BINARY_PATH"] = tempEnvVars["firestore"];
+    process.env["DATABASE_EMULATOR_BINARY_PATH"] = tempEnvVars["database"];
+    process.env["PUBSUB_EMULATOR_BINARY_PATH"] = tempEnvVars["pubsub"];
+  });
   it("should match the basename of remoteUrl", () => {
     checkDownloadPath(Emulators.FIRESTORE);
     checkDownloadPath(Emulators.DATABASE);
     checkDownloadPath(Emulators.PUBSUB);
   });
+
+  it("should apply environment varable overrides", () => {
+    process.env["FIRESTORE_EMULATOR_BINARY_PATH"] = "my/fake/firestore";
+    process.env["DATABASE_EMULATOR_BINARY_PATH"] = "my/fake/database";
+    process.env["PUBSUB_EMULATOR_BINARY_PATH"] = "my/fake/pubsub";
+
+    expect(downloadableEmulators.getDownloadDetails(Emulators.FIRESTORE).binaryPath).to.equal(
+      "my/fake/firestore",
+    );
+    expect(downloadableEmulators.getDownloadDetails(Emulators.DATABASE).binaryPath).to.equal(
+      "my/fake/database",
+    );
+    expect(downloadableEmulators.getDownloadDetails(Emulators.PUBSUB).binaryPath).to.equal(
+      "my/fake/pubsub",
+    );
+    expect(chmodStub.callCount).to.equal(3);
+  });
 });