The Firebase Local Emulator Suite can be installed and configured for different
prototype and test environments, anything from one-off prototyping sessions to
production-scale continuous integration workflows.
## Install the Local Emulator Suite
Before installing the Emulator Suite you will need:
- [Node.js](https://nodejs.org/en/download) version 16.0 or higher.
- [Java](https://jdk.java.net) JDK version 11 or higher.
To install the Emulator Suite:
1. Install the [Firebase CLI](https://firebase.google.com/docs/cli.md.txt). If you don't already have the Firebase CLI installed, [install it now](https://firebase.google.com/docs/cli.md.txt#install_the_firebase_cli). You will need CLI version 8.14.0 or higher to use the Emulator Suite. You can check which version you have installed using the following command:
```
firebase --version
```
2. If you haven't already done so, initialize the current working directory as a Firebase project, following the onscreen prompts to specify which products to use:
```
firebase init
```
3. Set up the Emulator Suite. This command starts a configuration wizard that lets you select emulators of interest, download the corresponding emulator binary files, and set emulator ports if the defaults are not appropriate.
```
firebase init emulators
```
Once an emulator is installed, no update checks are performed and no additional
automatic downloads will occur until you update your Firebase CLI version.
## Configure Emulator Suite
You can optionally configure the emulators' network ports and path to Security
Rules definitions in the `firebase.json` file:
- Change emulator ports by running `firebase init emulators` or by editing `firebase.json` manually.
- Change the path to Security Rules definitions by editing `firebase.json` manually.
If you don't configure these settings, the emulators will listen on their
default ports, and the Cloud Firestore, Realtime Database and Cloud Storage for Firebase
emulators will run with open data security.
| Command | Description |
|---|---|
| **init emulators** | Start an emulator initialization wizard. Identify emulators to be installed and optionally specify emulator port settings. `init emulators` is non-destructive; accepting defaults will preserve the current emulator configuration. |
### Port configuration
Each emulator binds to a different port on your machine with a preferred default
value.
| **Emulator** | **Default Port** |
|---|---|
| Authentication | 9099 |
| App Hosting | 5002 |
| Emulator Suite UI | 4000 |
| Cloud Functions | 5001 |
| Eventarc | 9299 |
| Realtime Database | 9000 |
| Cloud Firestore | 8080 |
| Cloud Storage for Firebase | 9199 |
| Firebase Hosting | 5000 |
| Pub/Sub | 8085 |
### Project ID configuration
Depending on how you invoke emulators, you may run multiple instances of an
emulator using different Firebase project IDs or multiple emulator instances
for a given project ID. In such cases, emulator instances are running in a
separate environment.
It's generally a good practice to set one project ID for all emulator
invocations, so the Emulator Suite UI, different product emulators, and all
running instances of a particular emulator can communicate correctly in all
cases.
Local Emulator Suite issues warnings when it detects multiple project IDs in
the environment, though you can override this behavior by setting the
`singleProjectMode` key to `false` in your `firebase.json`.
You can check project ID declaration(s) for mismatches in:
- **The default project in the command line.** By default, the project ID will be taken on startup from the project selected with `firebase init` or `firebase use`. To view the list of projects (and see which one is selected) use `firebase projects:list`.
- **Rules unit tests.** The project ID is often specified in calls to the Rules Unit Testing library methods `initializeTestEnvironment` or `initializeTestApp`.
- **The command line `--project` flag.** Passing the Firebase CLI `--project` flag overrides the default project. You'll need to ensure the value of the flag matches the project ID in unit tests and app initialization.
Also check platform-specific project ID configurations you've set while
configuring your [Apple platforms](https://firebase.google.com/docs/ios/setup.md.txt#add-config-file),
[Android](https://firebase.google.com/docs/android/setup.md.txt#add-config-file), and [web](https://firebase.google.com/docs/web/setup.md.txt#add-sdks-initialize) projects.
### Security Rules configuration
The emulators will take Security Rules configuration from the `database`,
`firestore` and `storage` configuration keys in `firebase.json`.
```json
{
// Existing firebase configuration ...
"database": {
"rules": "database.rules.json"
},
"firestore": {
"rules": "firestore.rules"
},
"storage": {
"rules": "storage.rules"
}
// ...
// Optional emulator configuration. Default
// values are used if absent.
"emulators": {
"singleProjectMode": false, // do not warn on detection of multiple project IDs
"firestore": {
"port": "8080"
},
"ui": {
"enabled": true, // Default is `true`
"port": 4000 // If unspecified, see CLI log for selected port
},
"auth": {
"port": "9099"
},
"pubsub": {
"port": "8085"
}
}
}
```
### Specifying Java options
The Realtime Database emulator, Cloud Firestore emulator, and part of
Cloud Storage for Firebase emulator are based on Java, which can be customized
with JVM flags via the environment variable `JAVA_TOOL_OPTIONS`.
For example, if you experience Java heap space related errors, you may increase
the maximum Java heap size to 4GB:
```bash
export JAVA_TOOL_OPTIONS="-Xmx4g"
firebase emulators:start
```
Multiple flags can be specified in quotes separated by spaces, like
`JAVA_TOOL_OPTIONS="-Xms2g -Xmx4g"`. The flags only affect the Java-based
components of the emulators and have no effect on other parts of the
Firebase CLI, such as Emulator Suite UI.
## Start up emulators
You can start emulators to run until manually terminated, or to run for the
duration of a designated test script then automatically shut down.
Command Description `emulators:start`
Start emulators for the Firebase products configured in
`firebase.json`. Emulator processes will continue running
until explicitly stopped. Calling `emulators:start` will
download the emulators to `~/.cache/firebase/emulators/` if
they aren't already installed.
Flag Description `--only` *Optional.* Limit which emulators start. Supply a comma-separated list of emulator names, specifying one or more of the following: `auth`, `database`, `firestore`, `functions`, `hosting`, or `pubsub`. `--inspect-functions DEBUG_PORT` *Optional.* Use with the Cloud Functions emulator to enable breakpoint debugging of functions at the specified port (or the default port `9229` if argument omitted). Note that when this flag is supplied, the Cloud Functions emulator switches to a special serialized execution mode in which functions are executed in a single process, in sequential (FIFO) order; this simplifies function debugging, though the behavior differs from multi-process, parallel execution of functions in the cloud. `--export-on-exit=` *Optional.* Use with the Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator. Instruct the emulator(s) to export data to a directory when shutdown occurs, as described for the `emulators:export` command. The export directory can be specified with this flag: `firebase emulators:start --export-on-exit=./saved-data`. If `--import` is used, the export path defaults to the same; for example: `firebase emulators:start --import=./data-path --export-on-exit`. Lastly, if preferred, pass different directory paths to the `--import` and `--export-on-exit` flags. `--import=IMPORT_DIRECTORY` *Optional.* Use with the Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator. Import data saved using the `--export-on-exit` startup option or the `emulators:export` command to a running Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator instance. Any data currently in emulator memory will be overwritten. `--log-verbosity=VERBOSITY` *Optional.* Reduces the amount of logging output from the emulators to reduce noise in the console and in log files. Valid values are `DEBUG`, `INFO`, `QUIET`, `SILENT`. `emulators:exec PATH/TO/SCRIPT`
Run the script at PATH/TO/SCRIPT after starting emulators for
the Firebase products configured in `firebase.json`. Emulator
processes will automatically stop when the script has finished running.
Flag Description `--only` *Optional.* Limit which emulators start. Supply a comma-separated list of emulator names, specifying one or more of the following: `firestore`, `database`, `functions`, `hosting`, or `pubsub`. `--inspect-functions DEBUG_PORT` *Optional.* Use with the Cloud Functions emulator to enable breakpoint debugging of functions at the specified port (or the default port `9229` if argument omitted). Note that when this flag is supplied, the Cloud Functions emulator switches to a special serialized execution mode in which functions are executed in a single process, in sequential (FIFO) order; this simplifies function debugging, though the behavior differs from multi-process, parallel execution of functions in the cloud. `--export-on-exit=` *Optional.* Use with the Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator. Instruct the emulator(s) to export data to a directory when shutdown occurs, as described for the `emulators:export` command. The export directory can be specified with this flag: `firebase emulators:start --export-on-exit=./saved-data`. If `--import` is used, the export path defaults to the same; for example: `firebase emulators:start --import=./data-path --export-on-exit`. Lastly, if preferred, pass different directory paths to the `--import` and `--export-on-exit` flags. `--import=IMPORT_DIRECTORY` *Optional.* Use with the Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator. Import data saved using the `--export-on-exit` startup option or the `emulators:export` command to a running Authentication, Cloud Firestore, Realtime Database, or Cloud Storage for Firebase emulator instance. Any data currently in emulator memory will be overwritten. `--ui` *Optional.* Run the Emulator UI during execution. `--log-verbosity=VERBOSITY` *Optional.* Reduces the amount of logging output from the emulators to reduce noise in the console and in log files. Valid values are `DEBUG`, `INFO`, `QUIET`, `SILENT`.
The `firebase emulators:exec` method is generally more appropriate for
continuous integration workflows.
## Export and import emulator data
You can export data from the Authentication, Cloud Firestore, Realtime Database and
Cloud Storage for Firebase emulators to use as a shareable, common baseline data
set. These data sets can be imported using the `--import` flag, as
described above.
|---|---|
| **emulators:export export_directory** | *Authentication, Cloud Firestore, Realtime Database or Cloud Storage for Firebase emulator*. Export data from a running Cloud Firestore, Realtime Database or Cloud Storage for Firebase emulator instance. The specified `export_directory` will be created if it does not already exist. If the specified directory exists, you will be prompted to confirm that the previous export data should be overwritten. You can skip this prompt using the **--force** flag. The export directory contains a data manifest file, `firebase-export-metadata.json`. You can instruct the emulators to export data automatically when they shutdown using the `--export-on-exit` flags described above. |
## Integrate with your CI system
### Running containerized Emulator Suite images
Installation and configuration of the Emulator Suite with containers in a
typical CI setup is straightforward.
There are a few issues to note:
- JAR files are installed and cached at `~/.cache/firebase/emulators/`.
- You may want to add this path to your CI cache configuration to avoid repeated downloads.
- If you do not have a `firebase.json` file in your repository, you must add a
command line argument to the `emulators:start` or `emulators:exec` command
to specify which emulators should be started. For example,
`--only functions,firestore`.
### Generate an auth token (Hosting emulator only)
If your continuous integration workflows rely on Firebase Hosting , then you
will need to log in using a token in order to run `firebase emulators:exec`. The
other emulators do not require login.
> [!NOTE]
> **Note:** If you have configured hosting in `firebase.json` but do not need it in CI test setups, use the `--only` flag to `emulators:start` or `emulators:exec` to include only the emulators that you need.
To generate a token, run `firebase login:ci` on your local environment; this should not be performed from a CI system. Follow instructions to authenticate. You should only need to perform this step once per project, since the token will be valid across builds. The token should be treated like a password; make sure it is kept secret.
If your CI environment allows you to specify environment variables that can be
used in the build scripts, simply create an environment variable called
`FIREBASE_TOKEN`, with the value being the access token string. The Firebase CLI
will automatically pick up the `FIREBASE_TOKEN` environment variable and the
emulators will start properly.
As a last resort, you can simply include the token in your build script, but
make sure that untrusted parties do not have access. For this hard-coded
approach, you can add `--token "YOUR_TOKEN_STRING_HERE"` to the
`firebase emulators:exec` command.
## Use the Emulator Hub REST API
### List running emulators
To list the currently running emulators, send a `GET` request to the `/emulators`
endpoint of the Emulator Hub.
```bash
curl localhost:4400/emulators
```
The result will be a JSON object listing all running emulators and their
host/port configuration, for example:
```json
{
"hub":{
"name": "hub",
"host": "localhost",
"port": 4400
},
"functions": {
"name": "functions",
"host": "localhost",
"port": 5001
}
"firestore": {
"name": "firestore",
"host": "localhost",
"port": 8080
}
}
```
### Enable / Disable Background Function Triggers
In some situations you will need to temporarily disable local function and
extension triggers. For example you may want to delete all of the data in the
Cloud Firestore emulator without triggering any `onDelete` functions that
are running in the Cloud Functions or Extensions emulators.
To temporarily disable local function triggers, send a `PUT` request to the
`/functions/disableBackgroundTriggers` endpoint of the Emulator Hub.
```bash
curl -X PUT localhost:4400/functions/disableBackgroundTriggers
```
The result will be a JSON object detailing the current state.
```json
{
"enabled": false
}
```
To enable local function triggers after they have been disabled, send a `PUT`
request to the `/functions/enableBackgroundTriggers` endpoint of the Emulator
Hub.
```bash
curl -X PUT localhost:4400/functions/enableBackgroundTriggers
```
The result will be a JSON object detailing the current state.
```json
{
"enabled": true
}
```
## Emulator SDK integrations
The tables in this section indicate which emulators are supported by client
and Admin SDKs. *Future* means emulator support is planned but not yet
available.
### Client SDK availability
| | **Android** | **Apple platforms** | **Web** | **Firebase UI Android** | **Firebase UI iOS** | **Firebase UI Web** |
|---|---|---|---|---|---|---|
| Realtime Database | 19.4.0 | 7.2.0 | 8.0.0 | 6.4.0 | Future | N/A |
| Cloud Firestore | 21.6.0 | 7.2.0 | 8.0.0 | 6.4.0 | Future | N/A |
| Authentication | 20.0.0 | 7.0.0 | 8.0.0 | 7.0.0 | Future | 4.7.2 |
| Cloud Storage for Firebase | 20.0.0 | 8.0.0 | 8.4.0 | 7.0.0 | 11.0.0 | N/A |
| Cloud Functions | 19.1.0 | 7.2.0 | 8.0.0 | N/A | N/A | N/A |
| Hosting | N/A | N/A | N/A | N/A | N/A | N/A |
| Extensions | N/A | N/A | N/A | N/A | N/A | N/A |
### Admin SDK availability
| | **Node** | **Java** | **Python** | **Go** |
|---|---|---|---|---|
| Realtime Database | 8.6.0 | 6.10.0 | 2.18.0 | Future |
| Cloud Firestore | 8.0.0 | 6.10.0 | 3.0.0 | 1.0.0 |
| Authentication | 9.3.0 | 7.2.0 | 5.0.0 | 4.2.0 |
| Cloud Storage for Firebase | 9.8.0 | Future | Future | Future |
| Cloud Functions | N/A | N/A | N/A | N/A |
| Hosting | N/A | N/A | N/A | N/A |
| Extensions | N/A | N/A | N/A | N/A |