Deploying MongoDB ReplicaSet with Docker (Public VPS IP and User Authentication Required)

Introduction

Deploying a MongoDB ReplicaSet with Docker efficiently builds a robust database system, ensuring high availability and fault tolerance. I'd like to share the detailed steps based on my real-world experience below.

So the other day, I was working on a project using NestJS + Prisma + MongoDB, and it turned out that Prisma requires a ReplicaSet to work properly.

Deployment Steps

1. Create Directory Structure

   Prepare the necessary directories for data and configuration:
   

   mkdir -p mongodb-replicaset/data/{primary,secondary1,secondary2}
   cd mongodb-replicaset
   
   

2. Create a Keyfile for Authentication

   The keyfile ensures secure communication between nodes.
   

   mkdir -p mongodb-replicaset/keyfile
   openssl rand -base64 756 > keyfile/mongodb-keyfile
   chmod 400 keyfile/mongodb-keyfile
   sudo chown 999:999 keyfile/mongodb-keyfile
   
   

3. Create a Docker Compose File

   Use the following Docker Compose configuration to initialize the ReplicaSet:
   

   version: '3.8'
   
   services:
     mongo-primary:
       image: mongo:latest
       container_name: mongo-primary
       command: mongod --bind_ip_all --replSet rs0 --port 27017 --auth --keyFile /data/keyfile/mongodb-keyfile
       ports:
         - "27017:27017"
       volumes:
         - ./data/primary:/data/db
         - ./keyfile:/data/keyfile
       networks:
         - mongo-network
       restart: always
   
     mongo-secondary-1:
       image: mongo:latest
       container_name: mongo-secondary-1
       command: mongod --bind_ip_all --replSet rs0 --port 27017 --auth --keyFile /data/keyfile/mongodb-keyfile
       ports:
         - "27018:27017"
       volumes:
         - ./data/secondary1:/data/db
         - ./keyfile:/data/keyfile
       networks:
         - mongo-network
       restart: always
       depends_on:
         - mongo-primary
   
     mongo-secondary-2:
       image: mongo:latest
       container_name: mongo-secondary-2
       command: mongod --bind_ip_all --replSet rs0 --port 27017 --auth --keyFile /data/keyfile/mongodb-keyfile
       ports:
         - "27019:27017"
       volumes:
         - ./data/secondary2:/data/db
         - ./keyfile:/data/keyfile
       networks:
         - mongo-network
       restart: always
       depends_on:
         - mongo-primary
   
   networks:
     mongo-network:
       driver: bridge
   
   

4. Start Docker Compose
   

   docker-compose up -d
   
   

5. Configure the ReplicaSet

   Connect to the primary node and initialize the ReplicaSet:
   

   docker exec -it mongo-primary mongosh
   rs.initiate({
     _id: "rs0",
     members: [
       { _id: 0, host: "mongo-primary:27017", priority: 2 },
       { _id: 1, host: "mongo-secondary-1:27017", priority: 1 },
       { _id: 2, host: "mongo-secondary-2:27017", priority: 1 }
     ]
   });
   
   

6. Create an Admin User
   

   use admin;
   db.createUser({
     user: "adminUser",
     pwd: "securePassword",
     roles: [ { role: "root", db: "admin" } ]
   });
   
   

7. MongoDB Connection String with Authentication (ReplicaSet + Public IP)

In local

mongodb://appUser:appPassword@mongo-primary:27017,mongo-secondary-1:27017,mongo-secondary-2:27017/myApp?replicaSet=rs0&authSource=myApp

For public IP

mongodb://appUser:appPassword@your_vps_ip:27017,your_vps_ip:27018,your_vps_ip:27019/myApp?replicaSet=rs0&authSource=myApp

Conclusion

With the above steps, you can easily and effectively deploy a MongoDB ReplicaSet with Docker. Don't forget to verify your connection and consider any additional security configurations as needed.