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Integrating with third-party tooling

This document outlines how to configure EAS Build for some common scenarios, such as monorepos and repositories with private dependencies. The examples described here do not provide step-by-step instructions to set up EAS Build from scratch. Instead, they explain the changes from the standard process that are necessary to accommodate the given scenario.

EAS Build-specific npm hooks

There are three EAS Build-specific npm hooks that you can set in your package.json. See the Android build process and iOS build process docs to get a better understanding about the internals of the build process.
  • eas-build-pre-install - executed before EAS Build runs yarn install
  • eas-build-post-install - the behavior depends on the platform:
    • for Android, after yarn install has completed
    • for iOS, after yarn install and pod install have completed
  • eas-build-pre-upload-artifacts - this hook is triggered almost at the end of the build process, just before EAS Build uploads the build artifacts to AWS S3
This is an example of how your package.json might look like:
  "main": "index.js",
  "scripts": {
    "eas-build-pre-install": "echo 123",
    "eas-build-post-install": "echo 456",
    "eas-build-pre-upload-artifacts": "echo 789",
    "android": "expo run:android",
    "ios": "expo run:ios",
    "web": "expo start --web",
    "start": "react-native start",
    "test": "jest"
  "dependencies": {
    "expo": "~40.0.0"
    // ...
  "devDependencies": {
    // ...
  "jest": {
    "preset": "react-native"
  "private": true

  • Run all EAS CLI commands from the root of the app directory. For example: if your project exists inside of your git repository at apps/my-app, then run eas build from there.
  • All files related to EAS Build, such as eas.json and credentials.json, should be in the root of the app directory. If you have multiple apps that use EAS Build in your monorepo, each app directory will have its own copy of these files.
  • If you are building a managed project in a monorepo, please refer to byCedric/eas-monorepo-example for a working example. You will need to set up symlinks with expo-yarn-workspaces in order to ensure that Expo module packages can be resolved. A better solution for this is in progress and should be available by SDK 43.
  • If your project needs additional setup beyond what is provided, add a postinstall step to package.json in your project that builds all necessary dependencies in other workspaces. For example:
  "scripts": {
    "postinstall": "cd ../.. && yarn build"

  • Configure your project in a way that relies on the NPM_TOKEN env variable to authenticate with private repositories.
  • Add NPM_TOKEN to your account or project's secrets. See the secret environment variables docs to learn how to do this.
Secret creation UI filled
Before setting up private packages, check the existing configuration described in the build server infrastructure page under .npmrc and yarnrc.yml to verify that it won't affect your setup.

By default the EAS npm cache won't work with yarn v1, because yarn.lock files contain URLs to registries for every package and yarn does not provide any way to override it. The issue is fixed in yarn v2, but the yarn team does not plan to backport it to yarn v1. If you want to take advantage of the npm cache, you can use the eas-build-pre-install script to override the registry in your yarn.lock.
 "scripts": {
    "eas-build-pre-install": "bash -c \"[ ! -z \\\"EAS_BUILD_NPM_CACHE_URL\\\" ] && sed -i -e \\\"s#https://registry.yarnpkg.com#$EAS_BUILD_NPM_CACHE_URL#g\\\" yarn.lock\""

First, create a secret with a base64 encoded private SSH key that has permission to access submodule repositories. Next, add an eas-build-pre-install npm hook to check out those submodules, for example:
#!/usr/bin/env bash

mkdir -p ~/.ssh

# Real origin URl is lost during the packaging process, so if your
# submodules are defined using relative urls in .gitmodules then
# you need to restore it with:
# git remote set-url origin git@github.com:example/repo.git

# restore private key from env variable and generate public key
echo "$SSH_KEY_BASE64" | base64 -d > ~/.ssh/id_rsa
chmod 0600 ~/.ssh/id_rsa
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub

# add your git provider to the list of known hosts
ssh-keyscan github.com >> ~/.ssh/known_hosts

git submodule update --init