replica Set mongo docker-compose

I had a similar issue and resolved it with the following compose file:

version: "3.8"services:  mongo1:    image: mongo:4.2    container_name: mongo1    command: ["--replSet", "my-replica-set", "--bind_ip_all", "--port", "30001"]    volumes:      - ./data/mongo-1:/data/db    ports:      - 30001:30001    healthcheck:      test: test $$(echo "rs.initiate({_id:'my-replica-set',members:[{_id:0,host:\"mongo1:30001\"},{_id:1,host:\"mongo2:30002\"},{_id:2,host:\"mongo3:30003\"}]}).ok || rs.status().ok" | mongo --port 30001 --quiet) -eq 1      interval: 10s      start_period: 30s  mongo2:    image: mongo:4.2    container_name: mongo2    command: ["--replSet", "my-replica-set", "--bind_ip_all", "--port", "30002"]    volumes:      - ./data/mongo-2:/data/db    ports:      - 30002:30002  mongo3:    image: mongo:4.2    container_name: mongo3    command: ["--replSet", "my-replica-set", "--bind_ip_all", "--port", "30003"]    volumes:      - ./data/mongo-3:/data/db    ports:      - 30003:30003

with the following in my /etc/hosts file:

127.0.0.1       mongo1127.0.0.1       mongo2127.0.0.1       mongo3

I documented it in a GitHub repo and with a little blog post here:

https://github.com/UpSync-Dev/docker-compose-mongo-replica-set

https://www.upsync.dev/2021/02/02/run-mongo-replica-set.html

Update: This does not work! You do need to run rs.initiate()

With MongoDB 4.0, you don't need a 4th container to run a setup script. It is really simple to bring up a replicaSet of 3 containers:

version: "3"services:  mongo1:    hostname: mongo1    container_name: localmongo1    image: mongo:4.0-xenial    expose:      - 27017    restart: always    entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]  mongo2:    hostname: mongo2    container_name: localmongo2    image: mongo:4.0-xenial    expose:      - 27017    restart: always    entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]  mongo3:    hostname: mongo3    container_name: localmongo3    image: mongo:4.0-xenial    expose:      - 27017    restart: always    entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]

More info here: https://github.com/msound/localmongo/tree/4.0

I would adivse you to have a look at khezen/mongo.

You can deploy a mongo replica set across a 3 nodes docker swarm with the following:

version: '3'services:  replica1:    image: khezen/mongo:slim    deploy:      mode: replicated      replicas: 1      update_config:        parallelism: 1        delay: 10s      restart_policy:        condition: on-failure      palcement:        node.hostname: node-1    environment:      RS_NAME: shard1      SHARD_SVR: 'y'      AUTH: 'y'    volumes:      - /data/mongo/replica1:/data/db    networks:      - mongo_cluster  replica2:    image: khezen/mongo:slim    deploy:      mode: replicated      replicas: 1      update_config:        parallelism: 1        delay: 10s      restart_policy:        condition: on-failure      palcement:        node.hostname: node-2    environment:      RS_NAME: shard1      SHARD_SVR: 'y'      AUTH: 'y'    volumes:      - /data/mongo/replica2:/data/db    networks:      - mongo_cluster  replica3:    image: khezen/mongo:slim    deploy:      mode: replicated      replicas: 1      update_config:        parallelism: 1        delay: 10s      restart_policy:        condition: on-failure      palcement:        node.hostname: node-3    environment:      RS_NAME: shard1      SHARD_SVR: 'y'      MASTER: replica3      SLAVES: replica1 replica2      AUTH: 'y'    volumes:      - /data/mongo/replica3:/data/db    networks:      - mongo_clusternetworks:  mongo_cluster:    driver: overlay

disclaimer: I am the maintainer of this image.