What is Expo EAS? What core services does it include?

Expo EAS (Expo Application Services) is a set of cloud services officially provided by Expo, designed to simplify the build, submit, and update process for Expo apps. EAS provides a complete solution from development to deployment.

EAS Core Services:

1. EAS Build

EAS Build is a cloud build service that can build Android APK/IPA and iOS IPA files.

Main Features:

• Cloud builds without local native environment configuration
• Supports both development and production build configurations
• Automatic handling of signing and certificates
• Build history and log viewing
• Parallel build support

Usage:

bash
# Install EAS CLI
npm install -g eas-cli

# Configure EAS
eas build:configure

# Build Android app
eas build --platform android

# Build iOS app (requires Apple Developer account)
eas build --platform ios

# Build development version
eas build --profile development --platform android

1. EAS Submit

EAS Submit automatically submits built apps to app stores.

Supported Platforms:

• Google Play Store
• Apple App Store

Usage:

bash
# Submit to Google Play
eas submit --platform android --latest

# Submit to App Store
eas submit --platform ios --latest

1. EAS Update

EAS Update allows updating apps via OTA (Over-the-Air) without resubmitting to app stores.

Main Features:

• Instant push updates
• Support for rolling back to previous versions
• Fine-grained update control
• Update grouping and release strategies

Usage:

bash
# Create update
eas update --branch production --message "Fix bug"

# View update history
eas update:list

# Rollback update
eas update:rollback --branch production

EAS Configuration File:

Create eas.json configuration file in project root:

json
{
  "cli": {
    "version": ">= 5.2.0"
  },
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal"
    },
    "preview": {
      "distribution": "internal",
      "android": {
        "buildType": "apk"
      }
    },
    "production": {
      "android": {
        "buildType": "app-bundle"
      },
      "ios": {
        "autoIncrement": true
      }
    }
  },
  "submit": {
    "production": {
      "android": {
        "serviceAccountKeyPath": "./google-service-account.json"
      },
      "ios": {
        "appleId": "your-apple-id@email.com",
        "ascAppId": "YOUR_APP_STORE_CONNECT_APP_ID",
        "appleTeamId": "YOUR_TEAM_ID"
      }
    }
  }
}

Environment Variable Management:

EAS supports injecting environment variables during builds:

bash
# Set environment variable
eas secret:create --name API_KEY --value "your-api-key"

# Use in code
const apiKey = process.env.API_KEY;

Best Practices:

1. CI/CD Integration: Integrate EAS Build into GitHub Actions or other CI/CD workflows

2. Version Management: Use Git branches and EAS Update branches to manage different environments

3. Build Optimization: Reasonably configure build settings, distinguish between development and production environments

4. Monitoring and Logging: Regularly review build logs,及时发现和解决问题

5. Permission Management: Assign appropriate EAS permissions to team members

Limitations and Considerations:

• iOS builds require Apple Developer account and paid developer program
• Build time depends on project size and server load
• Free accounts have build count limits
• Some native features may require additional configuration

EAS greatly simplifies the Expo app deployment process, allowing developers to focus more on app development itself.