Simple API example with Postgres + Redis

What?

This is an example code to self-host an API with a local Postgres and redis installation, the project contains:

• Example Python FastAPI code

• Nginx rev-proxy to load balance between two servers

• Dockerfile to package and deploy the Python API

• Redis

• PostgresSQL DB

• Docker Compose file for local development.

How?

To bring the stack up:

docker-compose build && docker-compose up

To bring the stack down:

docker-compose down

Using the stack

Once the stack is up and running you can access the API via http://127.0.0.1:8083, as per default API servers will listen on http://127.0.0.1:5001 and http://127.0.0.1:5002, direct access will also work.

To test the API quickly is a good idea to use the Swagger frontend which can be found in http://127.0.0.1:8083/docs

A word about persistence

The compose file will create a docker volume to ensure that the DB is persisted across deployments, to wipe the db perform run: docker volume rm $VOLUME_NAME

Scaling the stack

In order to scale the stack there are two main things to do BEFORE:

1. In the Nginx proxy config, nginx.conf, add another entry for another server:

upstream loadbalancer {
    # Using Round Robin as load balancing method
    server 172.17.0.1:5001;
    server 172.17.0.1:5002;
    server 172.17.0.1:$PORTNUMBER;
}

2. Add another container definition in the docker-compose.yaml file:

    fastapi$NUMBER:
        build: app/.
        container_name: fastapi$NUMBER
        command: uvicorn app.main:app --host 0.0.0.0 --port $PORTNUMBER
        volumes:
            - ./app:/usr/src/app/
        ports:
            - "$PORTNUMBER:$PORTNUMBER"
        depends_on:
            - redis
            - postgres
        links:
            - "db:database"
            - "redis:cache"
        environment:
          - REDIS_HOST=cache
          - REDIS_PORT=6379
          - DB_HOST=database
          - DB_NAME=postgres
          - DB_USER=postgres
          - DB_PASSWORD=postgres

Once the two steps described above are done, bring down the stack docker-compose down and bring it up again docker-compose build && docker-compose up