MongoDB Replica Set with Docker

docker-compose.yml

version: '2'
services:
  mongo1:
    container_name: mongo1
    image: mongo:2.4
    expose:
      - 27017
    networks:
      - mongo
    command: mongod --replSet rs0 --smallfiles --oplogSize 128

  mongo2:
    container_name: mongo2
    image: mongo:2.4
    expose:
      - 27017
    networks:
      - mongo
    command: mongod --replSet rs0 --smallfiles --oplogSize 128

  mongo3:
    container_name: mongo3
    image: mongo:2.4
    expose:
      - 27017
    networks:
      - mongo
    command: mongod --replSet rs0 --smallfiles --oplogSize 128

networks:
  mongo:
    driver: bridge

Commands to run to initiate RS:

docker exec -it mongo1 mongo
connecting to: test
> rs.initiate()
> cfg = rs.conf()
> cfg.members[0].host = "mongo1:27017"
> rs.reconfig(cfg)
> rs.add("mongo2:27017")
> rs.add("mongo3:27017") 
> rs.status();