docker-compose mysql init sql is not executed

Question

I am trying to set up a mysql docker container and execute init sql script. Unfortunately the sql script is not executed. What am I doing wrong?

version: '3.3'
services:
  api:
    container_name: 'api'
    build: './api'
  ports:
    - target: 8080
      published: 8888
      protocol: tcp
      mode: host
  volumes:
    - './api:/go/src/app'
  depends_on:
    - 'mysql'
 mysql:
  image: 'mysql:latest'
  container_name: 'mysql'
  volumes:
    - ./db_data:/var/lib/mysql:rw
    - ./database/init.sql:/docker-entrypoint-initdb.d/init.sql:ro
  restart: always
  environment:
    MYSQL_USER: test
    MYSQL_PASSWORD: test
    MYSQL_ROOT_PASSWORD: test
    MYSQL_DATABASE: test
  ports:
    - '3306:3306'
volumes:
  db_data:

I execute file with docker-compose up -d --build

Answer 1

The docker-entrypoint-initdb.d folder will only be run once while the container is created (instantiated) so you actually have to do a docker-compose down -v to re-activate this for the next run.

If you want to be able to add sql files at any moment you can look here at a specialized MySql docker image... http://ivo2u.nl/o4

Answer 2

Many containerized applications, especially stateful ones, have a way of running init scripts (like the sql scripts here) and they are supposed to run only once.

And since they are stateful, the volumes are a source of truth for the containers on whether to run the init scripts or not on container restart.

Like in your case, deleting the folder used for bind mount or using a new named volume should re-run any init scripts present.