This compose file uses databack/mysql-backup to create preiodically backups from mysql service.

I keep all the environment variables in an .env file like example.env. It's well commented and gives the feeling of a config file.

---
version: '3.1'

services:

  db-backup:
    image: databack/mysql-backup
    container_name: app_db_backup
    env_file:
      - ./example.env
    environment:
      DB_PASS_FILE: /run/secrets/database_password
    secrets:
      - database_password
    volumes:
      - ./backup/database/:/backup
    depends_on:
      - db

The ./backup/database/ path should be owned by user 1005, otherwise the container is not able to copy the files to the backup target.

You can create a user and change the ownership of the directory:

$ sudo useradd --uid 1005 backup_user
$ sudo chown backup_user: ./backup/database/