How to change the default character set of mysql using docker-compose?

You can either build your own mysql image where you modify my.cnf, or modify the command that starts mysql’s daemon with --character-set-server=utf8mb4 and --collation-server=utf8_unicode_ci.

web:
    image: yetongxue/docker_test:1.2
    links:
      - "db"
    ports:
      - "8100:8000"
    volumes:
      - "/Users/yetongxue/docker_v/docker_test/media:/root/media"
    restart: always

db:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: qwerasdf
      MYSQL_DATABASE: docker_db
    restart: always
    volumes:
      - "/Users/yetongxue/docker_v/docker_test/db:/var/lib/mysql"
    command: ['mysqld', '--character-set-server=utf8mb4', '--collation-server=utf8mb4_unicode_ci']

I recommend using utf8mb4, as it can store up to “4 bytes per multibyte character” (https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html)