replica Set mongo docker-compose

Question

I\'m trying to configure a mongodb replicaSet using docker-compose, but when I stop the master container it seems that it doesn\'t pass to the secondary.

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Answer 1

I set up a gist with a guide on how to set it up using a docker-compose file and mongoose. https://gist.github.com/harveyconnor/518e088bad23a273cae6ba7fc4643549

Answer 2

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

Answer 3

I had similar problem in setting replica set up in a standalone mongodb service with authentication and here are what I ended up with.

docker-compose.yml:

version: '3.7'

services:
  
  ...

  db:
    image: mongo
    restart: always
    expose:
      - 27017
    environment:
      MONGO_INITDB_DATABASE: ${DATABASE_NAME}
      MONGO_INITDB_ROOT_USERNAME: ${DATABASE_USER}
      MONGO_INITDB_ROOT_PASSWORD: ${DATABASE_PASSWORD}
      MONGO_REPLICA_SET_NAME: ${MONGO_REPLICA_SET_NAME}
    command: ["--replSet", "${MONGO_REPLICA_SET_NAME}", "--bind_ip_all"]
    healthcheck:
      test: test $$(echo "rs.status().ok" | mongo -u $${MONGO_INITDB_ROOT_USERNAME} -p $${MONGO_INITDB_ROOT_PASSWORD} --quiet) -eq 1
      interval: 10s
      start_period: 30s
    volumes:
      - ./db:/data/db
      - ./scripts/set-credentials.sh:/docker-entrypoint-initdb.d/set-credentials.sh

  replica-setup:
    image: mongo
    restart: on-failure
    networks:
      default:
    volumes:
      - ./scripts/setup-replica.sh:/scripts/setup-replica.sh
    entrypoint: [ "bash", "/scripts/setup-replica.sh" ]
    depends_on:
      - db
    environment:
      MONGO_INITDB_ROOT_USERNAME: ${DATABASE_USER}
      MONGO_INITDB_ROOT_PASSWORD: ${DATABASE_PASSWORD}

./scripts/setup-replica.sh:

#!/bin/bash

MONGODB1=db

echo "Waiting for MongoDB startup..."
until curl http://${MONGODB1}:27017/serverStatus\?text\=1 2>&1 | grep uptime | head -1; do
  printf '.'
  sleep 1
done

# check if replica set is already initiated
RS_STATUS=$( mongo --quiet --host ${MONGODB1}:27017 -u $MONGO_INITDB_ROOT_USERNAME -p $MONGO_INITDB_ROOT_PASSWORD --eval "rs.status().ok" )
if [[ $RS_STATUS != 1 ]]
then
  echo "[INFO] Replication set config invalid. Reconfiguring now."
  RS_CONFIG_STATUS=$( mongo --quiet --host ${MONGODB1}:27017 -u $MONGO_INITDB_ROOT_USERNAME -p $MONGO_INITDB_ROOT_PASSWORD --eval "rs.status().codeName" )
  if [[ $RS_CONFIG_STATUS == 'InvalidReplicaSetConfig' ]]
  then
    mongo --quiet --host ${MONGODB1}:27017 -u $MONGO_INITDB_ROOT_USERNAME -p $MONGO_INITDB_ROOT_PASSWORD <<EOF
config = rs.config()
config.members[0].host = db # Here is important to set the host name of the db instance
rs.reconfig(config, {force: true})
EOF
  else
    echo "[INFO] MongoDB setup finished. Initiating replicata set."
    mongo --quiet --host ${MONGODB1}:27017 -u $MONGO_INITDB_ROOT_USERNAME -p $MONGO_INITDB_ROOT_PASSWORD --eval "rs.initiate()" > /dev/null
  fi
else
  echo "[INFO] Replication set already initiated."
fi

./scripts/set-credentials.sh:

#!/bin/bash
set -e

mongo -- "$MONGO_INITDB_DATABASE" <<EOF
    var rootUser = '$MONGO_INITDB_ROOT_USERNAME';
    var rootPassword = '$MONGO_INITDB_ROOT_PASSWORD';
    var admin = db.getSiblingDB('admin');
    admin.auth(rootUser, rootPassword);

    var user = '$MONGO_INITDB_ROOT_USERNAME';
    var password = '$MONGO_INITDB_ROOT_PASSWORD';
    db.createUser({user: user, pwd: password, roles: ["readWrite"]});
EOF

What I achieved through is:

• Setup a mongodb service with username/password authentication for a default collection
• Initialize replica set when it's first time running services
• Reconfigure replica set member when there's a previous db data
• Health check the mongodb service by checking replica set status

Answer 4

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_cluster

networks:
  mongo_cluster:
    driver: overlay

disclaimer: I am the maintainer of this image.