Expo Application Services (EAS) provides cloud infrastructure for building and distributing React Native apps. EAS Build handles native compilation and signing in the cloud, EAS Update enables over-the-air JavaScript updates, and the Expo Dev Client enables custom native module development.
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What does EAS Build provide that running expo build locally does not?
EAS Build runs native compilation (Xcode for iOS, Gradle for Android) on Expo's cloud infrastructure. It manages code signing credentials, stores build artifacts, and provides build history — eliminating the need for local Xcode or Android Studio installations for CI/CD.
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A developer configures eas.json with multiple build profiles. What is the purpose of different profiles like development, preview, and production?
EAS Build profiles in eas.json define different build configurations: development builds include the Expo Dev Client for debugging, preview creates internal distribution builds, and production creates store-ready builds. Each profile can specify environment variables, distribution, and platform-specific settings.
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What is an EAS Update and how does it differ from a full EAS Build?
EAS Update publishes over-the-air (OTA) JavaScript bundle updates that existing app installs download automatically. Since only the JS bundle changes, there's no need to resubmit to app stores. Full EAS Builds are required when native code, dependencies, or permissions change.
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A developer runs eas build --profile production --platform ios. Where does EAS store the signing certificate and provisioning profile?
EAS manages iOS signing credentials (certificates and provisioning profiles) on Expo's secure credential storage. When you run eas credentials, EAS can automatically generate and store credentials, or you can upload existing ones. This enables CI/CD without secrets in the repository.
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What is the purpose of the Expo Dev Client (formerly Expo Go replacement) in an EAS development build?
The Expo Dev Client creates a custom development app that includes your project's specific native modules. Unlike the standard Expo Go app (which has a fixed set of modules), a dev client build lets you use any custom native module while still getting fast JavaScript refresh during development.