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Configuration with eas.json

eas.json is your go-to place for configuring EAS Build. It is located at the root of your project next to your package.json. It looks something like this:
{
  "builds": {
    "android": {
      "release": {
        "workflow": "generic"
      }
    },
    "ios": {
      "release": {
        "workflow": "generic"
      }
    }
  }
}
The JSON object under the builds key contains the platforms that you want to build for. The example above declares that you want to build app binaries for both Android and iOS platforms.
Each object under the platform key can contain multiple build profiles. Every build profile can have an arbitrary name. The default profile that is expected by EAS CLI to exist is release (if you'd like to build your app using another build profile you need to specify it with a parameter - eas build --platform android --profile foobar). In the example, there are two build profiles (one for Android and one for iOS) and they are both named release. However, they could be named foo or bar or whatever you'd like.
Generally, the schema of this file looks like this:
{
  "builds": {
    "PLATFORM_NAME": {
      "BUILD_PROFILE_NAME_1": { ... },
      "BUILD_PROFILE_NAME_2": { ... },
      ...,
    },
    ...
  }
}
where PLATFORM_NAME is one of android or ios.

Build Profiles

There are two types of build profiles: generic and managed.
Generic projects make almost no assumptions about your project's structure. The only requirement is that your project follows the general structure of React Native projects. This means there are android and ios directories in the root directory with the Gradle and Xcode projects, respectively. Whether you've intialized your project with expo init --template bare-minimum or with npx react-native init, you can build it with EAS Build.
Managed projects are much simpler in terms of the project's structure and the knowledge needed to start developing your application. Those projects don't have the native code in the repository and they are tightly coupled with Expo. Basically, by managed projects, we mean projects initialized with expo init using a managed workflow template (like blank, blank-typescript, or tabs).

Android

Generic project

The schema of a build profile for a generic Android project looks like this:
{
  "workflow": "generic",
  "credentialsSource": "local" | "remote" | "auto", // default: "auto"
  "withoutCredentials": boolean, // default: false
  "gradleCommand": string, // default: ":app:bundleRelease"
  "artifactPath": string, // default: "android/app/build/outputs/**/*.{apk,aab}"
  "releaseChannel": string, // default: "default"
  "distribution": "store" | "internal" // default: "store"
}
  • "workflow": "generic" indicates that your project is a generic one.
  • credentialsSource defines the source of credentials for this build profile. If you want to provide your own credentials.json file, set this to local (learn more on this here). If you want to use the credentials EAS already has stored for you, choose remote. If you're not sure what to do, choose auto (this is the default option).
  • withoutCredentials: when set to true, EAS CLI won't require you to configure credentials when building the app using this profile. This comes in handy when you want to build debug binaries and the debug keystore is checked in to the repository. The default is false.
  • gradleCommand defines the Gradle task to be run on EAS servers to build your project. You can set it to any valid Gradle task, e.g. :app:assembleDebug to build a debug binary. The default Gradle command is :app:bundleRelease.
  • artifactPath is the path (or pattern) where EAS Build is going to look for the build artifacts. EAS Build uses the fast-glob npm package for pattern matching (see their README to learn more about the syntax you can use). The default value is android/app/build/outputs/**/*.{apk,aab}.
  • releaseChannel is the release channel for the expo-updates package (Learn more about this). If you do not specify a channel, your binary will pull releases from the default channel. If you do not use expo-updates in your project then this property will have no effect.
  • distribution is the flow of distributing your app. If you choose internal you'll be able to share your build URLs with anyone, and they will be able to install the builds to their devices straight from the Expo website. When using internal, make sure the gradleCommand produces an APK file (e.g. :app:assembleRelease). Otherwise, the sharable URL will be useless. The default is store which means your build URLs won't be sharable. Learn more about internal distribution.

Examples

This is the minimal working example. EAS CLI will ask you for the app's credentials, the project will be built with the ./gradlew :app:bundleRelease command, and you'll be provided with the URL to the android/app/build/outputs/bundle/release/app-release.aab file.
{
  "workflow": "generic"
}
If you'd like to build a release APK, use this example:
{
  "workflow": "generic",
  "gradleCommand": ":app:assembleRelease",
  "artifactPath": "android/app/build/outputs/apk/release/app-release.apk"
}
If you'd like to build a debug APK use the following example. Also, make sure the debug keystore is checked in to the repository.
{
  "workflow": "generic",
  "withoutCredentials": true,
  "gradleCommand": ":app:assembleDebug",
  "artifactPath": "android/app/build/outputs/apk/debug/app-debug.apk"
}

Managed Project

The schema of a build profile for a managed Android project looks like this:
{
  "workflow": "managed",
  "credentialsSource": "local" | "remote" | "auto", // default: "auto"
  "buildType": "app-bundle" | "apk", // default: "app-bundle"
  "releaseChannel": string, // default: "default"
  "distribution": "store" | "internal" // default: "store"
}
  • "workflow": "managed" indicates that your project is a managed one.
  • credentialsSource defines the source of credentials for this build profile. If you want to provide your own credentials.json file, set this to local (learn more on this here). If you want to use the credentials EAS already has stored for you, choose remote. If you're not sure what to do, choose auto (this is the default option).
  • buildType when set to app-bundle produces an AAB archive but when set to apk produces an APK instead.
  • releaseChannel is the release channel for the expo-updates package (Learn more about this). If you do not specify a channel, your binary will pull releases from the default channel. If you do not use expo-updates in your project then this property will have no effect.
  • distribution is the flow of distributing your app. If you choose internal you'll be able to share your build URLs with anyone, and they will be able to install the builds to their devices straight from the Expo website. When distribution is internal, buildType needs to be set to apk. The default is store which means your build URLs won't be sharable. Learn more about internal distribution.

Examples

This is the minimal working example. EAS CLI will ask you for the app's credentials, an AAB file will be produced.
{
  "workflow": "managed"
}
If you'd like to build a release APK instead, use the following example:
{
  "workflow": "managed",
  "buildType": "apk"
}

iOS

Generic Project

The schema of a build profile for a generic iOS project looks like this:
{
  "workflow": "generic",
  "credentialsSource": "local" | "remote" | "auto", // default: "auto"
  "scheme": string,
  "artifactPath": string, // default: "ios/build/App.ipa"
  "releaseChannel": string, // default: "default"
  "distribution": "store" | "internal" // default: "store"
}
  • "workflow": "generic" indicates that your project is a generic one.
  • credentialsSource defines the source of credentials for this build profile. If you want to provide your own credentials.json file, set this to local (learn more on this here). If you want to use the credentials EAS already has stored for you, choose remote. If you're not sure what to do, choose auto (this is the default option).
  • scheme defines the Xcode project's scheme to build. You should set it if your project has multiple schemes. Please note that if the project has only one scheme, it will automatically be detected. However, if multiple schemes exist and this value is not set, EAS CLI will prompt you to select one of them.
  • artifactPath is the path (or pattern) where EAS Build is going to look for the build artifacts. EAS Build uses the fast-glob npm package for pattern matching, (see their README to learn more about the syntax you can use). You should modify that path only if you are using a custom Gymfile. The default is ios/build/App.ipa.
  • releaseChannel is the release channel for the expo-updates package (Learn more about this). If you do not specify a channel, your binary will pull releases from the default channel. If you do not use expo-updates in your project then this property will have no effect.
  • distribution is the flow of distributing your app. If you choose internal you'll be able to share your build URLs with anyone, and they will be able to install the builds to their devices straight from the Expo website. The default is store which means your build URLs won't be sharable. Learn more about internal distribution.

Examples

This is the minimal working example. EAS CLI will ask you for the app's credentials and you'll be provided with the URL to the ios/build/App.ipa file.
{
  "workflow": "generic"
}
If you'd like to build your iOS project with a custom Gymfile (learn more on this here) where you've defined a different output directory than ios/build, use the following example:
{
  "workflow": "generic",
  "artifactPath": "ios/my/build/directory/RNApp.ipa" 
}

Managed Project

The schema of a build profile for a managed iOS project looks like this:
{
  "workflow": "managed",
  "credentialsSource": "local" | "remote" | "auto", // default: "auto"
  "releaseChannel": string, // default: "default"
  "distribution": "store" | "internal" // default: "store"
}
  • "workflow": "managed" indicates that your project is a managed one.
  • credentialsSource defines the source of credentials for this build profile. If you want to provide your own credentials.json file, set this to local (learn more on this here). If you want to use the credentials EAS already has stored for you, choose remote. If you're not sure what to do, choose auto (this is the default option).
  • releaseChannel is the release channel for the expo-updates package (Learn more about this). If you do not specify a channel, your binary will pull releases from the default channel. If you do not use expo-updates in your project then this property will have no effect.
  • distribution is the flow of distributing your app. If you choose internal you'll be able to share your build URLs with anyone, and they will be able to install the builds to their devices straight from the Expo website. The default is store which means your build URLs won't be sharable. Learn more Internal Distribution.

Examples

This is the minimal working example. EAS CLI will ask you for the app's credentials and you'll be provided with the URL to the ios/build/App.ipa file.
{
  "workflow": "managed"
}

Overall Example

The following example of eas.json configures both Android and iOS builds:
{
  "builds": {
    "android": {
      "release": {
        "workflow": "generic"
      },
      "debug": {
        "workflow": "generic",
        "withoutCredentials": true,
        "gradleCommand": ":app:assembleDebug",
        "artifactPath": "android/app/build/outputs/apk/debug/app-debug.apk"
      }
    },
    "ios": {
      "release": {
        "workflow": "generic",
        "artifactPath": "ios/my/build/directory/RNApp.ipa"
      }
    }
  }
}
For Android, there are two build profiles - release and debug. The release profile is just a basic generic profile. On the other hand, debug will let you build a debug APK for your project. If you want to build using the debug profile, run eas build --platform android --profile debug.
For iOS, we've defined a generic profile for the project which takes advantage of a custom Gymfile, hence the custom artifactPath field.