Summary#

Recently, I was developing an API with NestJS and needed to find a way to upload and serve static files (assets) --- such as images, documents, and other files --- in a secure and practical way.

After doing a quick search using GPT, I decided to use MinIO, which is an object storage solution compatible with the AWS S3 protocol, but that runs locally (or anywhere) via Docker.

In this post, I’ll share how I organized the project, the configuration using Docker Compose, and how I integrated the API with MinIO to upload files and make them publicly accessible via URL.

Docker#

The project runs in Docker containers, orchestrated by Docker Compose, with the following main services:

• api: NestJS backend, exposed on port 5400
• minio: object storage server (S3-compatible), on ports 9000 (API) and 9001 (web console)
• postgres: PostgreSQL database for persistence
• redis: cache and session store
• minio-init: special container used to initialize buckets and define policies in MinIO using mc (MinIO client)

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services:
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  api:
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    build:
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      context: .
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      dockerfile: ./Dockerfile
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    ports:
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      - "5400:5400"
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    env_file:
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      - ./.env.production
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    depends_on:
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      postgres:
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        condition: service_healthy
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      minio:
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        condition: service_started
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  minio:
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    image: quay.io/minio/minio:latest
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    command: server /data --console-address ":9001"
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    ports:
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      - "9000:9000"
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      - "9001:9001"
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    env_file:
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      - ./.env.production
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    volumes:
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      - minio_data:/data
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    healthcheck:
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      test: ["CMD", "curl", "-f", "http://localhost:9000/minio/health/ready"]
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      interval: 5s
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      timeout: 3s
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      retries: 10
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  minio-init:
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    image: minio/mc
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    depends_on:
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      minio:
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        condition: service_healthy
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    entrypoint: >
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      /bin/sh -c "
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      mc alias set local http://minio:9000 $MINIO_ROOT_USER $MINIO_ROOT_PASSWORD &&
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      mc mb -p local/$S3_BUCKET || true &&
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      mc mb -p local/posts || true &&
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      mc anonymous set download local/$S3_BUCKET &&
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      mc anonymous set download local/posts
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      "
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    env_file:
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      - ./.env.production
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volumes:
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  minio_data:

• MinIO runs with the web console available at http://localhost:9001, where you can view and manage buckets.
• The minio-init container runs after MinIO becomes healthy and executes commands using the mc client to:
  • Create the buckets defined in the $S3_BUCKET variable and the posts bucket.
  • Set those buckets as public for anonymous download (meaning anyone can view and download the files).

The command used in the docker-compose file for the minio-init container:

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mc anonymous set download local/$S3_BUCKET
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mc anonymous set download local/posts

Sets the buckets as publicly accessible for anonymous download, allowing anyone to access the files directly via URL.

The public URL to access a file is:

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http://localhost:9000/<bucket>/<file-name>

For example:

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http://localhost:9000/posts/foto.png

Service#

Example of the service that handles the integration using the @aws-sdk/client-s3 package:

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// (service implementation omitted for brevity – use your original TypeScript code here)

Source#

If you’d like to see the complete backend code, including the full setup and integrations, it’s available on my GitHub:
👉 https://github.com/nathan2slime/apl-atani