# Migrate from Create React App — Replace process.env.REACT_APP_*

> Automated codemod to migrate from Create React App's process.env.REACT_APP_* to REP runtime environment variables. Drop build-time env var dependency.

Source: https://rep-protocol.dev/guides/migration/from-cra/

## Automated migration

```bash
npx @rep-protocol/codemod --framework cra src/
```

### What it transforms

```typescript
// Before
const apiUrl = process.env.REACT_APP_API_URL;
const flags = process.env.REACT_APP_FEATURE_FLAGS;

// After
import { rep } from '@rep-protocol/sdk';
const apiUrl = rep.get('API_URL');
const flags = rep.get('FEATURE_FLAGS');
```

Only `REACT_APP_*` prefixed variables are transformed. Other `process.env.*` access is left unchanged.

### Preview first

```bash
npx @rep-protocol/codemod --framework cra --dry-run src/
```

## Manual migration

1. **Rename environment variables:**
   ```bash
   REACT_APP_API_URL        → REP_PUBLIC_API_URL
   REACT_APP_ANALYTICS_KEY  → REP_SENSITIVE_ANALYTICS_KEY
   ```

2. **Update code:**
   ```typescript
   import { rep } from '@rep-protocol/sdk';
   const apiUrl = rep.get('API_URL', 'http://localhost:3000');
   ```

3. **Install the SDK:**
   ```bash
   npm install @rep-protocol/sdk
   ```

## Post-migration cleanup

1. Remove `react-app-env.d.ts` (CRA's auto-generated type declarations)
2. Remove `.env.production` and `.env.staging` files
3. Run `rep typegen` for typed access
4. Update your Dockerfile to include the REP gateway