Step-by-Step Guide for Setting Up a MongoDB Cluster in Linux

How To Set Up A MongoDB Cluster in Linux – Step-by-Step Guide

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Overview

A robust NoSQL database, MongoDB is renowned for its adaptability and scalability. By distributing data among several servers, a MongoDB cluster allows for high availability and horizontal scaling. This blog post will walk you through the process of configuring a Linux MongoDB replica set cluster.

One of the most widely used NoSQL databases, MongoDB is well-known for its scalability, flexibility, and capacity to manage massive data sets. When high availability and scalability are required, as in financial systems, gaming applications, or e-commerce platforms, a MongoDB cluster is essential. With thorough, simple-to-follow instructions and examples from real-world situations, this blog will assist you in setting up a MongoDB cluster on Linux.

Step-by-Step Guide for Setting Up a MongoDB Cluster in Linux
Step-by-Step Guide for Setting Up a MongoDB Cluster in Linux

Imagine running an online store like Amazon.  Millions of users are concurrently browsing products, adding items to baskets, and placing orders during periods of peak sales. A single database server can’t handle such a massive workload efficiently. This is where a MongoDB cluster comes into play.

  • Horizontal Scaling: By distributing the data among several servers, horizontal scaling makes sure that even with high traffic volumes, everything runs well and smoothly.
  • High Availability: Replica sets ensure that your application continues to function even in the event of a server failure.

Let’s now begin configuring a Linux MongoDB replica set cluster!

Prerequisites:

  1. Spin up 3 Virtual Machines in any cloud provider of your choice.

You need three Linux servers to form the cluster. We’ll call them:

  • mongo-1 (Primary Node)
  • mongo-2 (Secondary Node)
  • mongo-3 (Secondary Node)

2. Also Enable Networking Between Nodes: Ensure all servers can communicate with each other over the network. Open the MongoDB port (27017) in your firewall/NSG Rules.

To check if the connectivity is successfully established, use the below command from any of the servers:

telnet <MONGO-IP> 27017

Step 1: Install MongoDB on All Servers

Use the following commands on each server:

sudo apt-get -y install gnupg

sudo wget https://repo.percona.com/apt/percona-release_latest.$(lsb_release -sc)_all.deb

 dpkg -i percona-release_latest.$(lsb_release -sc)_all.deb

 sudo apt update && sudo percona-release enable psmdb-44 release && sudo apt update 

 sudo apt -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install percona-server-mongodb=4.4.22-21.focal

 sudo systemctl daemon-reload && sudo systemctl enable mongod

 sudo systemctl start mongod

These commands can be found in the Official MongoDB Documentation as well.

Step 2: Configure MongoDB for Replication

MongoDB requires some adjustments to support clustering.

Edit MongoDB Configuration On Each Server:

  • Open the MongoDB configuration file:
sudo nano /etc/mongod.conf
  • Bind IP to allow cluster communication:
net:
  bindIp: 127.0.0.1,<server_ip>
  • Enable replica set:
replication:
  replSetName: "mongo-rs"

Restart MongoDB

sudo systemctl restart mongod.

Step 3: Initialize the Replica Set

Once all the servers are configured, it’s time to form the cluster now.

SSH into each VM and Connect to MongoDB Shell.

  1. mongo
  2. Initialize the Replica Set: Run the following command on the primary node:
rs.initiate({
_id: "mongo-rs",
members: [
{ _id: 0, host: "mongo-1:27017" },
{ _id: 1, host: "mongo-2:27017" },
{ _id: 2, host: "mongo-3:27017" }
]
});

This tells MongoDB that these three servers are part of the replica set.

  1. Verify the Configuration
rs.status();

If everything is set up correctly, you’ll see that one node is the primary, and the others are secondaries.

Step 4: Test the Cluster

Check Replica Set Status On any node, connect to the MongoDB shell and run:

rs.status()

  1. Look for the “stateStr” field in the output:
    • PRIMARY: Node handling read/write operations.
    • SECONDARY: Nodes replicating data from the primary.

Test Failover Stop the primary node:

sudo systemctl stop mongod

Check if one of the secondary nodes becomes the primary.

Step 6: Adding Authentication (Optional but Recommended)

Enable Security in MongoDB Config File:

security:

  authorization: enabled

Create an Admin User:

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

Restart MongoDB Services:

sudo systemctl restart mongod

Connect to MongoDB with Authentication:

mongo -u admin -p <PASSWORD> --authenticationDatabase admin

Conclusion

Well done! You have successfully installed a MongoDB cluster on Linux. In addition to offering high availability and resilient to failures, this configuration guarantees that your application can manage unforeseen outages and increasing data needs. A MongoDB cluster is a dependable option for contemporary data solutions, regardless of whether you’re operating a business system or developing a startup.

Check out the official MongoDB documentation for additional details.

Cheers to clustering !!

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