EAS Build vs Local Metro Bundles: Choosing the Right Build Strategy

Insight

When you need a reproducible, platform‑specific binary (e.g., App Store or Play Store upload), EAS Build shines: it runs in a clean Docker environment, handles native code, and caches dependencies across runs. For quick iteration on UI tweaks or debugging, a local Metro bundle (expo start) is faster because it skips the heavyweight native compilation step. The sweet spot is a hybrid CI pipeline: run unit tests and lint locally, then trigger an EAS Build only on merge to main or when native modules change.

Example

// eas.json – minimal config for CI
{
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal",
      "android": { "gradleCommand": "assembleDebug" },
      "ios": { "simulator": true }
    },
    "production": {
      "android": { "gradleCommand": "assembleRelease" },
      "ios": { "workflow": "managed" }
    }
  }
}

Takeaway

Use local Metro for rapid UI cycles, but gate every native change through EAS Build in CI. This keeps builds fast for developers while guaranteeing that production binaries are built in a consistent, reproducible environment.