# Develop and test AWS Cloud applications using LocalStack and Docker — Connecting to LocalStack from containerized Node app

> Now that you have learnt how to connect a non-containerized Node.js application to LocalStack, it's time to explore the necessary changes to run the complete application stack in a containerized environment.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-docker-e6b45ed6d21263d3a6e6>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.478062+00:00`
- Tags: `reference-seed`, `docker`, `guides`, `develop`, `test`, `aws`, `cloud`, `applications`, `using`, `localstack`, `connecting`, `containerized`

## Provenance

- Source: <https://github.com/docker/docs/blob/3a9d778562f39bcc0be46255b013c6a3ca526244/content/guides/localstack.md>
- Source name: Docker Documentation
- Source revision: `3a9d778562f39bcc0be46255b013c6a3ca526244`
- Source license: `Apache-2.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

Now that you have learnt how to connect a non-containerized Node.js application to LocalStack, it's time to explore the necessary changes to run the complete application stack in a containerized environment. To achieve this, you will create a Compose file specifying all required services - frontend, backend, database, and LocalStack.

Examine the Docker Compose file.

The following Docker Compose file defines four services: backend, frontend, mongodb, and localstack. The backend and frontend services are your Node.js applications, while mongodb provides a database and localstack simulates AWS services like S3.

The backend service depends on localstack and mongodb services, ensuring they are running before it starts. It also uses a .env file for environment variables. The frontend service depends on the backend and sets the API URL. The mongodb service uses a persistent volume for data storage, and localstack is configured to run the S3 service. This setup lets you to develop and test your application locally with AWS-like services.

Bounded code example (external data; do not execute automatically):
```yaml
   services:
     backend:
       build:
         context: ./backend
         dockerfile: Dockerfile
       ports:
         - 5000:5000
       depends_on:
         - localstack
         - mongodb
       env_file:
         - backend/.env

     frontend:
       build:
         context: ./frontend
         dockerfile: Dockerfile
       ports:
         - 5173:5173
       depends_on:
         - backend
       environment:
         - REACT_APP_API_URL=http://backend:5000/api

     mongodb:
       image: mongo
       container_name: mongodb
       volumes:
         - mongodbdata:/data/db
       ports:
         - 27017:27017

     localstack:
       image: localstack/localstack
       container_name: localstack
       ports:
         - 4566:4566
       environment:
         - SERVICES=s3
         - GATEWAY_LISTEN=0.0.0.0:4566
       volumes:
         - ./localstack:/etc/localstack/init/ready.d
```

Modify the .env file under the backend/ directory to have the resources connect using the internal network names.

&gt; [!TIP] &gt; Given the previous Compose file, the app would connect to LocalStack using the hostname localstack while Mongo would connect using the hostname mongodb. …

Attribution: Adapted from Docker Documentation under Apache-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.