Fixing some issues around handling multiple firestore DBs #9770
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Summary of ChangesHello @joehan, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request significantly enhances the Firebase Firestore emulator by introducing comprehensive support for multiple Firestore databases. It addresses long-standing limitations and bugs, allowing developers to configure, emulate, and manage security rules for several Firestore instances within a single project. This change improves the development workflow for applications utilizing multiple Firestore databases by making the emulator more robust and feature-complete. Highlights
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Code Review
The pull request successfully addresses the issues related to handling multiple Firestore databases during emulation and deployment. The changes in src/emulator/controller.ts correctly adapt the rule processing logic to support multiple configurations, and the FirestoreEmulatorArgs and updateRules method in src/emulator/firestoreEmulator.ts have been updated to reflect this. The new test cases in src/firestore/fsConfig.spec.ts provide good coverage for the getFirestoreConfig function's behavior with firestore:rules and firestore:indexes filters. However, there are a couple of areas that need attention to ensure correctness and efficiency.
| for (const c of this.args.rules) { | ||
| const rulesPath = c.rules; | ||
| this.rulesWatcher = chokidar.watch(rulesPath, { persistent: true, ignoreInitial: true }); | ||
| this.rulesWatcher.on("change", async () => { | ||
| // There have been some race conditions reported (on Windows) where reading the | ||
| // file too quickly after the watcher fires results in an empty file being read. | ||
| // Adding a small delay prevents that at very little cost. | ||
| await new Promise((res) => setTimeout(res, 5)); | ||
|
|
||
| utils.logLabeledBullet( | ||
| "firestore", | ||
| `Change detected, updating rules for ${c.database}...`, | ||
| ); | ||
| const newContent = fs.readFileSync(rulesPath, "utf8").toString(); | ||
| const issues = await this.updateRules(c.database, newContent); | ||
| if (issues) { | ||
| for (const issue of issues) { | ||
| utils.logWarning(this.prettyPrintRulesIssue(rulesPath, issue)); | ||
| } | ||
| } | ||
| } | ||
| if (issues.some((issue) => issue.severity === Severity.ERROR)) { | ||
| utils.logWarning("Failed to update rules"); | ||
| } else { | ||
| utils.logLabeledSuccess("firestore", "Rules updated."); | ||
| } | ||
| }); | ||
| if (issues.some((issue) => issue.severity === Severity.ERROR)) { | ||
| utils.logWarning("Failed to update rules"); | ||
| } else { | ||
| utils.logLabeledSuccess("firestore", "Rules updated."); | ||
| } | ||
| }); | ||
| } |
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The this.rulesWatcher is reassigned within the for...of loop. This means that only the chokidar.watch instance created for the last firestoreConfig in the this.args.rules array will be active. Consequently, changes to rule files for other databases will not be detected or trigger updates. To correctly watch all rule files, each chokidar.watch instance should be stored in a collection (e.g., an array of FSWatcher instances) and then iterated over when stopping the emulator.
const rulesWatchers: chokidar.FSWatcher[] = [];
for (const c of this.args.rules) {
const rulesPath = c.rules;
const watcher = chokidar.watch(rulesPath, { persistent: true, ignoreInitial: true });
watcher.on("change", async () => {
// There have been some race conditions reported (on Windows) where reading the
// file too quickly after the watcher fires results in an empty file being read.
// Adding a small delay prevents that at very little cost.
await new Promise((res) => setTimeout(res, 5));
utils.logLabeledBullet(
"firestore",
`Change detected, updating rules for ${c.database}...`
);
const newContent = fs.readFileSync(rulesPath, "utf8").toString();
const issues = await this.updateRules(c.database, newContent);
if (issues) {
for (const issue of issues) {
utils.logWarning(this.prettyPrintRulesIssue(rulesPath, issue));
}
}
if (issues.some((issue) => issue.severity === Severity.ERROR)) {
utils.logWarning("Failed to update rules");
} else {
utils.logLabeledSuccess("firestore", "Rules updated.");
}
});
rulesWatchers.push(watcher);
}
this.rulesWatcher = rulesWatchers; // Update the type of rulesWatcher to be FSWatcher[]
aalej
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aalej
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I can't seem to run the Firestore emulators. Given this test case https://github.com/aalej/pulls-9770, running firebase emulators:start will raise
Jan 21, 2026 9:50:13 PM com.google.cloud.datastore.emulator.firestore.CloudFirestore main
SEVERE: Exiting due to unexpected exception.
java.io.FileNotFoundException: [object Object],[object Object] (No such file or directory)
at java.base/java.io.FileInputStream.open0(Native Method)
at java.base/java.io.FileInputStream.open(FileInputStream.java:213)
at java.base/java.io.FileInputStream.<init>(FileInputStream.java:152)
at com.google.common.io.Files$FileByteSource.openStream(Files.java:140)
at com.google.common.io.Files$FileByteSource.read(Files.java:170)
at com.google.common.io.ByteSource$AsCharSource.read(ByteSource.java:534)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.init(CloudFirestore.java:186)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.startLocally(CloudFirestore.java:120)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.main(CloudFirestore.java:101)
Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/util/LegacySystemExit
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.main(CloudFirestore.java:106)
Caused by: java.lang.ClassNotFoundException: com.google.common.util.LegacySystemExit
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
... 1 more
| // TODO(VicVer09): b/269787702 | ||
| let rulesLocalPath; | ||
| let rulesFileFound; | ||
| const rules: { database: string; rules: string }[] = []; |
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I don't think the Firestore emulator binary accepts an array of objects for rules(I could be wrong though, I can't find any docs on how to use the binary).
Running the emulator with the code below(from what I can tell, this is what we do with the CLI):
minimal firestore emulator spawn code
const childProcess = require("node:child_process")
const BINARY_PATH = "/Users/alejandromarco/.cache/firebase/emulators/cloud-firestore-emulator-v1.20.2.jar"
let emulator = {}
emulator.instance = childProcess.spawn("java", [
'-Dgoogle.cloud_firestore.debug_log_level=FINE',
'-Duser.language=en',
'-jar',
BINARY_PATH,
'--host',
'127.0.0.1',
'--port',
8080,
'--websocket_port',
9150,
'--project_id',
'demo-project',
'--rules',
[
{
database: '(default)',
rules: '/Users/alejandromarco/Desktop/firebase-tools/issues/9770/firestore.rules'
},
{
database: 'non-default',
rules: '/Users/alejandromarco/Desktop/firebase-tools/issues/9770/firestore.non-default.rules'
}
],
'--single_project_mode',
true
])
emulator.instance.stderr?.on("data", (data) => {
console.log("DEBUG", data.toString());
});
emulator.instance.once("exit", async (code, signal) => {
if (signal) {
console.log(`Firestore emulator has exited upon receiving signal: ${signal}`);
} else if (code && code !== 0 && code !== /* SIGINT */ 130) {
console.log("Firestore emulator", `has exited with code: ${code}`);
}
});Will raise an error java.io.FileNotFoundException: [object Object],[object Object] (No such file or directory)
error output
$ node .
DEBUG Jan 21, 2026 10:19:04 PM com.google.cloud.datastore.emulator.firestore.CloudFirestore main
SEVERE: Exiting due to unexpected exception.
java.io.FileNotFoundException: [object Object],[object Object] (No such file or directory)
at java.base/java.io.FileInputStream.open0(Native Method)
at java.base/java.io.FileInputStream.open(FileInputStream.java:213)
at java.base/java.io.FileInputStream.<init>(FileInputStream.java:152)
at com.google.common.io.Files$FileByteSource.openStream(Files.java:140)
at com.google.common.io.Files$FileByteSource.read(Files.java:170)
at com.google.common.io.ByteSource$AsCharSource.read(ByteSource.java:534)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.init(CloudFirestore.java:186)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.startLocally(CloudFirestore.java:120)
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.main(CloudFirestore.java:101)
DEBUG Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/util/LegacySystemExit
at com.google.cloud.datastore.emulator.firestore.CloudFirestore.main(CloudFirestore.java:106)
Caused by: java.lang.ClassNotFoundException: com.google.common.util.LegacySystemExit
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
... 1 more
Firestore emulator has exited with code: 1
Changing the code the use a string for rules makes the process run again
minimal firestore spawn code
const childProcess = require("node:child_process")
const BINARY_PATH = "/Users/alejandromarco/.cache/firebase/emulators/cloud-firestore-emulator-v1.20.2.jar"
let emulator = {}
emulator.instance = childProcess.spawn("java", [
'-Dgoogle.cloud_firestore.debug_log_level=FINE',
'-Duser.language=en',
'-jar',
BINARY_PATH,
'--host',
'127.0.0.1',
'--port',
8080,
'--websocket_port',
9150,
'--project_id',
'demo-project',
'--rules',
'/Users/alejandromarco/Desktop/firebase-tools/issues/9770/firestore.rules',
'--single_project_mode',
true
])
emulator.instance.stderr?.on("data", (data) => {
console.log("DEBUG", data.toString());
});
emulator.instance.once("exit", async (code, signal) => {
if (signal) {
console.log(`Firestore emulator has exited upon receiving signal: ${signal}`);
} else if (code && code !== 0 && code !== /* SIGINT */ 130) {
console.log("Firestore emulator", `has exited with code: ${code}`);
}
});outputs
log output
$ node working.js
DEBUG Jan 21, 2026 10:18:45 PM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start
INFO: Started WebSocket server on ws://127.0.0.1:9150
2 participants
Description
Fixes some issues related to handling multiple Firestore DBs during emulation and deployment. Fixes #9742 and #8114