TIL: Local development against "S3"

TIL: Local development against “S3”

February 19, 2025

I had to update a Django service to use S3 instead of local file storage recently. Here's how I set up Minio (a self-hostable S3-compatible data store) for local development.

I use Docker Compose (well, Finch Compose, but same difference) to run local versions of Postgres and S3.

Here's the docker-compose.yaml file for Minio:

services:
  minio:
    image: minio/minio
    ports:
      - "64040:9000" # API port
      - "64041:9001" # Web dashboard port
    volumes:
      - minio_data:/data
    environment:
      MINIO_ROOT_USER: minioadmin
      MINIO_ROOT_PASSWORD: minioadmin
    command: server /data --console-address ":9001"

volumes:
  minio_data:

Note that:

We're setting a default username and password for local development. Obviously use proper secrets management for a more serious environment.
We're re-mapping the service's ports to a random high port since other services sometimes try to bind 9000 or 9001.

Once you've docker compose up'd this, you can log in to the admin console at localhost:64041 and create your development bucket and access keys.

In your application you'll need to configure:

An S3 url:
- use http://127.0.0.1:64040 for running natively or
- http://minio:9000 if you're in a different Docker Compose container
An S3 region: use us-east-1
An S3 bucket name: use whatever you created via the admin
An access key and secret key: use the keys you created via the admin

This should also work for developing against S3 compatible services like:

etc.