Connect your app to the Cloud Functions Emulator

Before connecting your app to the Cloud Functions emulator, make sure that you understand the overall Firebase Local Emulator Suite workflow and that you install and configure the Local Emulator Suite.

Instrument your app to talk to the emulators

Callable Functions

If your prototype and test activities involve callable backend functions, configure interaction with the Cloud Functions for Firebase emulator like this:

Android

FirebaseFunctions.getInstance().useFunctionsEmulator("http://10.0.2.2:5001");
MainActivity.java

iOS - Swift

Functions.functions().useFunctionsEmulator(origin: "http://localhost:5001")
ViewController.swift

Web

firebase.functions().useFunctionsEmulator("http://localhost:5001")
emulator-suite.js

Note: Android only. Android network security configuration policies may affect how your code interacts with the Cloud Functions emulator, which serves data locally via unencrypted HTTP. Starting with Android 9 (API level 28), clear text communication is disabled by default. You can set up a network_security_config.xml file to whitelist the Cloud Functions emulator for development on localhost. See the relevant Android developer documentation.

HTTPS Functions

Each HTTPS function in your code will be served from the local emulator using the following URL format:

http://$HOST:$PORT/$PROJECT/$REGION/$NAME

For example a simple helloWorld function with the default host port and region would be served at:

https://localhost:5001/$PROJECT/us-central1/helloWorld

Background Triggered Functions

The Cloud Functions emulator supports background-triggered functions from the following sources:

• Realtime Database emulator
• Cloud Firestore emulator
• Cloud Pub/Sub emulator

To trigger background events, connect your app or test code to the emulators using the SDK for your platform.

What next?

• For a curated set of videos and detailed how-to examples, follow the Firebase Emulators Training Playlist.
• Learn more about the Cloud Functions for Firebase emulator at Run functions locally.