docker-compose with multiple databases

Question

I'm trying to figure out how to implement docker using docker-compose.yml with 2 databases imported from sql dumps.

httpd:
    container_name: webserver
    build: ./webserver/
    ports:
        - 80:80
    links:
        - mysql
        - mysql2
    volumes_from:
        - app

mysql:
    container_name: sqlserver
    image: mysql:latest
    ports:
        - 3306:3306
    volumes:
        - ./sqlserver:/docker-entrypoint-initdb.d
    environment:
        MYSQL_ROOT_PASSWORD: root
        MYSQL_DATABASE: dbname1
        MYSQL_USER: dbuser
        MYSQL_PASSWORD: dbpass

mysql2:
    extends: mysql
    container_name: sqlserver2
    environment:
        MYSQL_ROOT_PASSWORD: root
        MYSQL_DATABASE: dbname2
        MYSQL_USER: dbuser
        MYSQL_PASSWORD: dbpass

app:
    container_name: webdata
    image: php:latest
    volumes:
        - ../php:/var/www/html
    command: "true"

The above returns the following:

Kronos:mybuild avanche$ ./run.sh 
Creating sqlserver
Creating webdata
Creating sqlserver2

ERROR: for mysql2  driver failed programming external connectivity on endpoint sqlserver2 (6cae3dfe7997d3787a8d59a95c1b5164f7431041c1394128c14e5ae8efe647a8): Bind for 0.0.0.0:3306 failed: port is already allocated
Traceback (most recent call last):
  File "<string>", line 3, in <module>
  File "compose/cli/main.py", line 63, in main
AttributeError: 'ProjectError' object has no attribute 'msg'
docker-compose returned -1

Basically, I'm trying to get my whole stack setup in a single docker compose file, create 2 databases and import the respective sql dumps. Anyone have any suggestions?

Answer 1

Multiple databases in a single Docker container

The answers elsewhere on this page set up a dedicated container for each database, but a single MySQL server is capable of hosting multiple databases. Whether you should is a different question, but if you want multiple databases in a single container, here's an example.

docker-compose.yml:

version: '3'

volumes:
  db:
    driver: local

  services:
    db:
      image: mysql:5.7
      command: mysqld --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
      volumes:
        - ./docker/provision/mysql/init:/docker-entrypoint-initdb.d
      environment:
        MYSQL_ROOT_PASSWORD: local

docker/provision/mysql/init/01-databases.sql:

# create databases
CREATE DATABASE IF NOT EXISTS `primary`;
CREATE DATABASE IF NOT EXISTS `secondary`;

# create root user and grant rights
CREATE USER 'root'@'localhost' IDENTIFIED BY 'local';
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%';

How does this work?

This works because the MySQL Docker project has an entrypoint script that will run through all files in the /docker-entrypoint-initdb.d folder, if it exists. This is useful for setting up databases and initializing their schema and data. In docker-compose, we're using volumes to map that virtual folder to a folder on the host system.