Docker-compose check if mysql connection is ready

Question

I am trying to make sure that my app container does not run migrations / start until the db container is started and READY TO accept connections.

So I decided to use

Answer 1

This should be enough

version: '2.1'
services:
  mysql:
    image: mysql
    ports: ['3306:3306']
    environment:
      MYSQL_USER: myuser
      MYSQL_PASSWORD: mypassword
    healthcheck:
      test: mysqladmin ping -h 127.0.0.1 -u $$MYSQL_USER --password=$$MYSQL_PASSWORD