MongoDB replica set with docker and docker-compose

readme.md

How to setup

• Update mongod.env file with custom username and password
• Run docker compose up -d
• log on to mongo cli using below command

docker exec -it {docker-container-id} mongo -u "{your-username}" -p "{your-password}" --authenticationDatabase "admin"

• configure (initialize replicaset) on mongo-cli

rs.initiate({
    "_id" : "rs0",
    "members" : [
        {"_id" : 0,"host" : "mongodb1:27017"},
        {"_id" : 1,"host" : "mongodb2:27017"},
        {"_id" : 2,"host" : "mongodb3:27017"}
    ]
});

• option step to setup primority primary node (You may need to restart docker-compose)

conf = rs.config();
conf.members[0].priority = 2;
rs.reconfig(conf);

Optional step to create db user

use admin;
db.createUser({user: "cluster_admin",pwd: "password",roles: [ { role: "userAdminAnyDatabase", db: "admin" },  { "role" : "clusterAdmin", "db" : "admin" } ]});
db.auth("cluster_admin", "password"); 

References & Credis:

https://github.com/willitscale/learning-docker/tree/master/tutorial-12

https://www.youtube.com/watch?v=-XzMfd4XQak&t=1106s&ab_channel=WillitScale

docker-compose.yml

version: "3.0"

volumes:
  mongo-keys:
  mongo-data-1:
  mongo-data-2:
  mongo-data-3:

networks:
  rs0:
    driver: bridge
    ipam:
      driver: default
      config:
        - subnet: 172.10.5.0/24

services:

  mongo-keys:
    image: depop/openssl-bats
    volumes:
      - mongo-keys:/mongo-conf
    command: 'bash -c "openssl rand -base64 741 > /mongo-conf/mongodb-keyfile; chmod 600 /mongo-conf/mongodb-keyfile; chown 999 /mongo-conf/mongodb-keyfile"'

  # Primary
  mongodb1:
    image: mongo:4.0.4
    restart: always
    ulimits:
      nproc: 65535
      nofile:
        soft: 20000
        hard: 40000
    volumes:
      - mongo-keys:/opt/keyfile
      - mongo-data-1:/data/db
    env_file:
      ./mongod.env
    ports:
      - 27017:27017
    command: 'mongod --smallfiles --maxConns 51200 --auth --keyFile /opt/keyfile/mongodb-keyfile --replSet rs0'
    depends_on:
        - mongo-keys
    networks:
      rs0:
  # Worker 1
  mongodb2:
    image: mongo:4.0.4
    restart: always
    ulimits:
      nproc: 65535
      nofile:
        soft: 20000
        hard: 40000
    volumes:
      - mongo-keys:/opt/keyfile
      - mongo-data-2:/data/db
    env_file:
      ./mongod.env
    ports:
      - 27018:27017
    command: 'mongod --smallfiles --maxConns 51200 --auth --keyFile /opt/keyfile/mongodb-keyfile --replSet rs0'
    depends_on:
        - mongo-keys
    networks:
      rs0:
  # Worker 2
  mongodb3:
    image: mongo:4.0.4
    restart: always
    ulimits:
      nproc: 65535
      nofile:
        soft: 20000
        hard: 40000
    volumes:
      - mongo-keys:/opt/keyfile
      - mongo-data-3:/data/db
    env_file:
      ./mongod.env
    ports:
      - 27019:27017
    command: 'mongod --smallfiles --maxConns 51200 --auth --keyFile /opt/keyfile/mongodb-keyfile --replSet rs0'
    depends_on:
        - mongo-keys
    networks:
      rs0:

mongod.env

MONGO_INITDB_ROOT_USERNAME=YourUser
MONGO_INITDB_ROOT_PASSWORD=YourPassword