docker-compose-mongo-replica.yml

services:
  mongo1:
    image: mongo
    ports:
      - 127.0.0.1:27017:27017
    volumes:
      - ./mongo1:/data/db
    command: mongod --replSet replicaSet1
  mongo2:
    image: mongo
    ports:
      - 127.0.0.1:27018:27017
    volumes:
      - ./mongo2:/data/db
    command: mongod --replSet replicaSet1
  mongo:
    image: mongo
    depends_on:
      - mongo1
      - mongo2
    command: >
      sh -c "sleep 5 && mongosh --host mongo1:27017 --eval
      \"
      rs.initiate({
        _id : 'replicaSet1',
        members : [
          { _id: 0, host: 'mongo1:27017' },
          { _id: 1, host: 'mongo2:27017' }
        ]
      });
      \"
      "