.env

# .docker/.env
REDIS_HOST=redis
MONGO_HOST=mongo

db.env

# .docker/db.env
MYSQL_ROOT_USER=root
MYSQL_ROOT_PASSWORD=password

MYSQL_USER=root
MYSQL_PASSWORD=password

MYSQL_HOST=db
MYSQL_DATABASE=app_development

docker-compose.yml

version: '2'
services:
  app:
    build: .
    command: ./bin/startup.sh
    volumes:
      - .:/app
      - bundle:/bundle
    ports:
      - '3000:3000'
      - '4000:4000'
    env_file:
      - ./.docker/db.env
      - ./.docker/.env
    links:
      - db
      - redis
      - mongo

  db:
    image: mysql:5.7
    ports:
      - 3306
    env_file:
      - ./.docker/db.env
    volumes:
      - mysql:/var/lib/mysql

  redis:
    image: redis:latest
    volumes:
      - redis:/data

  mongo:
    image: mongo
    volumes:
      - mongo:/data/db

volumes:
  bundle:
  mysql:
  redis:
  mongo:

Procfile.docker

web: bundle exec rails s -b 0.0.0.0 -p 3000 -e ${RACK_ENV:-development}
react: npm start
resque: QUEUE=... bundle exec rake resque:work
resque_scheduler: bundle exec rake resque:scheduler
sphinx: bundle exec rake ts:start NODETACH=true
....

startup.sh

#!/bin/bash

# tells the bash script to exit whenever anything returns a non-zero return value.
set -e

./bin/wait-for-mysql.sh

# echo "[INFO] Precreate databases..."
# rake db:version || bundle exec rake db:setup

# echo "[INFO] Running db:migrate..."
# rake db:migrate

bundle exec foreman start -f Procfile.docker