strictPort: true,
  },
});
```

> [!NOTE]
> The `server` options in `vite.config.ts` are essential for running Vite inside Docker:
> - `host: true` allows the dev server to be accessible from outside the container.
> - `port: 5173` sets a consistent development port (must match the one exposed in Docker).
> - `strictPort: true` ensures Vite fails clearly if the port is unavailable, rather than switching silently.
> 
> For full details, refer to the [Vite server configuration docs](https://vitejs.dev/config/server-options.html).


After completing the previous steps, your project directory should now contain the following files:

```text
├── docker-reactjs-sample/
│ ├── Dockerfile
│ ├── Dockerfile.dev
│ ├── .dockerignore
│ ├── compose.yaml
│ ├── nginx.conf
│ └── README.Docker.md
```

### Step 4: Start Compose Watch

Run the following command from your project root to start your container in watch mode:

```console
$ docker compose watch react-dev
```

### Step 5: Test Compose Watch with React

To verify that Compose Watch is working correctly:

1. Open the `src/App.tsx` file in your text editor.

2. Locate the following line:

    ```html
    <h1>Vite + React</h1>
    ```

3. Change it to:

    ```html
    <h1>Hello from Docker Compose Watch</h1>
    ```

4. Save the file.

5. Open your browser at [http://localhost:5173](http://localhost:5173).

You should see the updated text appear instantly, without needing to rebuild the container manually. This confirms that file watching and automatic synchronization are working as expected.

---

## Summary

In this section, you set up a complete development and production workflow for your React.js application using Docker and Docker Compose.

Here's what you achieved:
- Created a `Dockerfile.dev` to streamline local development with hot reloading  
- Defined separate `react-dev` and `react-prod` services in your `compose.yaml` file  
- Enabled real-time file syncing using Compose Watch for a smoother development experience  
- Verified that live updates work seamlessly by modifying and previewing a component

With this setup, you're now equipped to build, run, and iterate on your React.js app entirely within containers—efficiently and consistently across environments.

---

## Related resources

Deepen your knowledge and improve your containerized development workflow with these guides:

- [Using Compose Watch](/manuals/compose/how-tos/file-watch.md) – Automatically sync source changes during development  
- [Multi-stage builds](/manuals/build/building/multi-stage.md) – Create efficient, production-ready Docker images  
- [Dockerfile best practices](/build/building/best-practices/) – Write clean, secure, and optimized Dockerfiles.
- [Compose file reference](/compose/compose-file/) – Learn the full syntax and options available for configuring services in `compose.yaml`.
- [Docker volumes](/storage/volumes/) – Persist and manage data between container runs  

## Next steps

In the next section, you'll learn how to run unit tests for your React.js application inside Docker containers. This ensures consistent testing across all environments and removes dependencies on local machine setup.