MongoDB is a super flexible NoSQL database, and if you’re running it on Debian 12 (Bookworm), setting up Master-Slave (Primary-Secondary) replication can help with scaling and data redundancy.

This guide will take you through installing, running, and configuring MongoDB 8 for a master-slave setup.

Prerequisites

• 3 Debian 12 servers:
  • Primary (Master): 10.11.33.111
  • Secondary 1 (Slave): 10.11.33.121
  • Secondary 2 (Slave): 10.11.33.122
• Root or sudo access on all servers
• Basic terminal knowledge (copy-paste helps too!)

Step 1: Install MongoDB 8 on Debian 12

1.1. Update Your System

Run this to make sure everything is fresh:

sudo apt update && sudo apt upgrade -y

1.2. Add the MongoDB Repo

MongoDB isn’t included in the default Debian repo, so we gotta add it manually.

Install gnupg and curl :

sudo apt-get install gnupg curl

Add MongoDB’s GPG key:

curl -fsSL https://pgp.mongodb.com/server-8.0.asc | sudo tee /usr/share/keyrings/mongodb-server-8.gpg

Add the official repo:

echo "deb [ signed-by=/usr/share/keyrings/mongodb-server-8.0.gpg ] http://repo.mongodb.org/apt/debian bookworm/mongodb-org/8.0 main" | sudo tee /etc/apt/sources.list.d/mongodb-org-8.0.list

Update package lists:

sudo apt update

1.3. Install MongoDB

sudo apt install -y mongodb-org

1.4. Start and Enable MongoDB

sudo systemctl enable mongod
sudo systemctl start mongod

1.5. Check If It’s Running

sudo systemctl status mongod

If you see Active (running), MongoDB is alive!

Step 2: Configure Master-Slave Setup

2.1. Setup the Master (Primary) Server

1. Open the MongoDB config: sudo nano /etc/mongod.conf
2. Edit these lines: net: bindIp: 0.0.0.0 port: 27017 replication: replSetName: "rs0"
3. Restart MongoDB: sudo systemctl restart mongod

2.2. Setup the Slaves (Secondary Servers)

Do this on 10.11.33.121 and 10.11.33.122:

1. Edit MongoDB config: sudo nano /etc/mongod.conf
2. Same changes as above: net: bindIp: 0.0.0.0 port: 27017 replication: replSetName: "rs0"
3. Restart MongoDB: sudo systemctl restart mongod

Step 3: Initialize the Replica Set

On the Primary (Master) Server 10.11.33.111, run:

mongosh

Then, initiate the replica set:

rs.initiate({
  _id: "rs0",
  members: [
    { _id: 0, host: "10.11.33.111:27017" },
    { _id: 1, host: "10.11.33.121:27017" },
    { _id: 2, host: "10.11.33.122:27017" }
  ]
});

Check if it’s working:

rs.status()

If it shows one Primary and two Secondaries, congrats, it’s working!

Step 4: Secure MongoDB with Authentication

By default, MongoDB is wide open! Let’s lock it down.

4.1. Create an Admin User

Run this on the Primary Server:

mongosh

Then add an admin:

use admin;
db.createUser({
  user: "admin",
  pwd: "SuperStrongPass123!",
  roles: [{ role: "root", db: "admin" }]
});

4.2. Enable Authentication

Edit MongoDB config on all servers:

sudo nano /etc/mongod.conf

Add:

security:
  authorization: enabled

Restart MongoDB:

sudo systemctl restart mongod

4.3. Verify

Try logging in:

mongosh -u admin -p SuperStrongPass123! --authenticationDatabase admin

Step 5: Test the Replication

5.1. Insert Data on Primary

On the Primary Server (10.11.33.111):

use testdb;
db.products.insertOne({ name: "Laptop", price: 1200 });

5.2. Read Data from Secondary

On a Secondary Server (10.11.33.121):

mongosh -u admin -p SuperStrongPass123! --authenticationDatabase admin

Enable reading from the slave:

rs.slaveOk();
use testdb;
db.products.find();

If you see { "name": "Laptop", "price": 1200 }, replication is working!

Step 6: Auto-Start MongoDB on Boot

Ensure MongoDB starts automatically:

sudo systemctl enable mongod

Final Thoughts

Boom! 💥 You now have a MongoDB 8 Master-Slave (Primary-Secondary) setup running on Debian 12. It’s secured, replicated, and production-ready.

Next Steps

• Backups: Use mongodump and mongorestore for safe data backups.
• Monitoring: Run mongostat and mongotop to track performance.
• Sharding: If you need even more scale, look into MongoDB sharding.

For more cool guides, check out diditho.com! 🚀