Please improve README for the Image

[eximius313]

https://hub.docker.com/_/redmine can be improved:

1. start a database container - PostgreSQL

$ docker run -d --name some-postgres --network some-network -e POSTGRES_PASSWORD=secret -e POSTGRES_USER=redmine postgres

could also contain POSTGRES_DB for the consistency (as MySQL example has it):

$ docker run -d --name some-postgres --network some-network -e POSTGRES_DB=redmine_db -e POSTGRES_USER=redmine -e POSTGRES_PASSWORD=secret postgres

2. start redmine

$ docker run -d --name some-redmine --network some-network -e REDMINE_DB_POSTGRES=some-postgres -e REDMINE_DB_USERNAME=redmine -e REDMINE_DB_PASSWORD=secret redmine

could also include REDMINE_DB_DATABASE in order to differentiate it from REDMINE_DB_POSTGRES and REDMINE_SECRET_KEY_BASE in order to be consistent with docker-compose.yaml:

$ docker run -d --name some-redmine --network some-network -e REDMINE_DB_POSTGRES=some-postgres-ip -e REDMINE_DB_DATABASE=redmine_db -e REDMINE_DB_USERNAME=redmine -e REDMINE_DB_PASSWORD=secret -e REDMINE_SECRET_KEY_BASE=supersecretkey redmine

3. compose.yaml could also have version for Postgresql and be enhanced of volumes and depends_on:

services:
  redmine:
    image: redmine
    restart: always
    environment:
      REDMINE_DB_POSTGRES: postgresql
      REDMINE_DB_DATABASE: redmine_db
      REDMINE_DB_USERNAME: redmine
      REDMINE_DB_PASSWORD: secret
      REDMINE_SECRET_KEY_BASE: supersecretkey
    ports:
      - 8080:3000
    volumes:
      - redmine_data:/usr/src/redmine/files
    depends_on:
      - postgresql

  postgresql:
    image: postgres:17-alpine
    restart: unless-stopped
    environment:
      POSTGRES_DB: redmine_db
      POSTGRES_USER: redmine
      POSTGRES_PASSWORD: secret
    volumes:
      - postgresql_data:/var/lib/postgresql/data

volumes:
  redmine_data:
  postgresql_data: