use fake "owner" credential when rtdb emulator env var is set (#2029)

* omit access token exchange if talking to an emulator

* [AUTOMATED]: Prettier Code Styling

* create TokenProvider interface and add EmulatorAuthTokenProvider

* [AUTOMATED]: Prettier Code Styling

* Update packages/database/src/core/EmulatorAuthTokenProvider.ts

Co-Authored-By: Yuchen Shi <[email protected]>

* break circular dependency by extracting env var constant

* [AUTOMATED]: Prettier Code Styling

* rename AuthTokenProvider -> FirebaseAuthTokenProvider etc.

* [AUTOMATED]: Prettier Code Styling

* fix ReadOnlyRestClient constructor comment

* poke travis CI

* remove unnecessary js docs

Author: jmwski

packages/database/src/core/AuthTokenProvider.ts

@@ -20,18 +20,28 @@ import { FirebaseAuthTokenData } from '@firebase/app-types/private';
 import { log, warn } from './util/util';
 
 /**
- * Abstraction around FirebaseApp's token fetching capabilities.
+ * An interface for token fetchers.
  */
-export class AuthTokenProvider {
-  /**
-   * @param {!FirebaseApp} app_
-   */
-  constructor(private app_: FirebaseApp) {}
-
+export interface AuthTokenProvider {
   /**
    * @param {boolean} forceRefresh
    * @return {!Promise<FirebaseAuthTokenData>}
    */
+  getToken(forceRefresh: boolean): Promise<FirebaseAuthTokenData>;
+
+  addTokenChangeListener(listener: (token: string | null) => void);
+
+  removeTokenChangeListener(listener: (token: string | null) => void);
+
+  notifyForInvalidToken();
+}
+
+/**
+ * Abstraction around FirebaseApp's token fetching capabilities.
+ */
+export class FirebaseAuthTokenProvider implements AuthTokenProvider {
+  constructor(private app_: FirebaseApp) {}
+
   getToken(forceRefresh: boolean): Promise<FirebaseAuthTokenData> {
     return this.app_['INTERNAL']['getToken'](forceRefresh).then(
       null,

packages/database/src/core/EmulatorAuthTokenProvider.ts

@@ -0,0 +1,44 @@
+/**
+ * @license
+ * Copyright 2019 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { FirebaseApp } from '@firebase/app-types';
+import { FirebaseAuthTokenData } from '@firebase/app-types/private';
+
+import { AuthTokenProvider } from './AuthTokenProvider';
+import { log, warn } from './util/util';
+
+class EmulatorAuthToken implements FirebaseAuthTokenData {
+  constructor(public accessToken: string) {}
+}
+
+export class EmulatorAuthTokenProvider implements AuthTokenProvider {
+  constructor(private app_: FirebaseApp) {}
+
+  getToken(forceRefresh: boolean): Promise<FirebaseAuthTokenData> {
+    return Promise.resolve(new EmulatorAuthToken('owner'));
+  }
+
+  addTokenChangeListener(listener: (token: string | null) => void) {}
+
+  removeTokenChangeListener(listener: (token: string | null) => void) {}
+
+  notifyForInvalidToken() {
+    let errorMessage =
+      'Database emulator unexpectedly rejected fake "owner" credentials.';
+    warn(errorMessage);
+  }
+}

packages/database/src/core/ReadonlyRestClient.ts

@@ -22,7 +22,10 @@ import { safeGet } from '@firebase/util';
 import { querystring } from '@firebase/util';
 import { ServerActions } from './ServerActions';
 import { RepoInfo } from './RepoInfo';
-import { AuthTokenProvider } from './AuthTokenProvider';
+import {
+  FirebaseAuthTokenProvider,
+  AuthTokenProvider
+} from './AuthTokenProvider';
 import { Query } from '../api/Query';
 
 /**

packages/database/src/core/Repo.ts

@@ -26,9 +26,20 @@ import { SparseSnapshotTree } from './SparseSnapshotTree';
 import { SyncTree } from './SyncTree';
 import { SnapshotHolder } from './SnapshotHolder';
 import { stringify } from '@firebase/util';
-import { beingCrawled, each, exceptionGuard, warn, log } from './util/util';
+import {
+  beingCrawled,
+  each,
+  exceptionGuard,
+  warn,
+  log,
+  FIREBASE_DATABASE_EMULATOR_HOST_VAR
+} from './util/util';
 import { map, isEmpty } from '@firebase/util';
-import { AuthTokenProvider } from './AuthTokenProvider';
+import {
+  FirebaseAuthTokenProvider,
+  AuthTokenProvider
+} from './AuthTokenProvider';
+import { EmulatorAuthTokenProvider } from './EmulatorAuthTokenProvider';
 import { StatsManager } from './stats/StatsManager';
 import { StatsReporter } from './stats/StatsReporter';
 import { StatsListener } from './stats/StatsListener';
@@ -81,7 +92,15 @@ export class Repo {
     forceRestClient: boolean,
     public app: FirebaseApp
   ) {
-    const authTokenProvider = new AuthTokenProvider(app);
+    let authTokenProvider: AuthTokenProvider;
+    if (
+      typeof process !== 'undefined' &&
+      process.env[FIREBASE_DATABASE_EMULATOR_HOST_VAR]
+    ) {
+      authTokenProvider = new EmulatorAuthTokenProvider(app);
+    } else {
+      authTokenProvider = new FirebaseAuthTokenProvider(app);
+    }
 
     this.stats_ = StatsManager.getCollection(repoInfo_);
 

packages/database/src/core/RepoManager.ts

@@ -18,7 +18,7 @@
 import { FirebaseApp } from '@firebase/app-types';
 import { safeGet } from '@firebase/util';
 import { Repo } from './Repo';
-import { fatal } from './util/util';
+import { fatal, FIREBASE_DATABASE_EMULATOR_HOST_VAR } from './util/util';
 import { parseRepoInfo, parseURL } from './util/libs/parser';
 import { validateUrl } from './util/validation';
 import './Repo_transaction';
@@ -28,16 +28,6 @@ import { RepoInfo } from './RepoInfo';
 /** @const {string} */
 const DATABASE_URL_OPTION = 'databaseURL';
 
-/**
- * This variable is also defined in the firebase node.js admin SDK. Before
- * modifying this definition, consult the definition in:
- *
- * https://github.com/firebase/firebase-admin-node
- *
- * and make sure the two are consistent.
- */
-const FIREBASE_DATABASE_EMULATOR_HOST_VAR = 'FIREBASE_DATABASE_EMULATOR_HOST';
-
 let _staticInstance: RepoManager;
 
 /**

packages/database/src/core/util/util.ts

@@ -31,6 +31,17 @@ import { Logger, LogLevel } from '@firebase/logger';
 
 const logClient = new Logger('@firebase/database');
 
+/**
+ * Environment variable for enabling interaction with the Firebase Realtime Database
+ * emulator. If set, the module will present the endpoint with a fake "owner" credential
+ * (see EmulatorAuthTokenProvider) instead of one belonging to a real account.
+ *
+ * The expected format for this variable is '<HOST>:<PORT>'. The transfer protocol must be
+ * omitted and will default to 'http'.
+ */
+export const FIREBASE_DATABASE_EMULATOR_HOST_VAR =
+  'FIREBASE_DATABASE_EMULATOR_HOST';
+
 /**
  * Returns a locally-unique ID (generated by just incrementing up from 0 each time its called).
  * @type {function(): number} Generated ID.