MongoDB Cross-Region Disaster Recovery (DR) on AWS EC2: Step-by-Step Guide
In today’s high-availability landscape, disaster recovery (DR) is more than a best practice—it's a requirement. This tutorial walks you through implementing a cross-region MongoDB DR solution using EC2 instances with public IPs. You’ll learn to replicate data between AWS regions to ensure business continuity even in regional outages.
🧭 Architecture Overview
The DR architecture consists of:
A primary MongoDB instance running in one AWS region.
A replica set member (secondary) in a separate AWS region.
Data replication between these two nodes.
📌 Diagram on page 1 shows a simple two-region EC2-based MongoDB setup with replication arrows connecting the nodes.
🔧 Implementation Guide
1. EC2 Instance Setup
Launch two Ubuntu EC2 instances, one in each AWS region.
Security Groups must allow:
- Inbound traffic on TCP port 27017 (MongoDB default port) from known IPs.
2. Install MongoDB
Run these commands on both instances:
sudo apt-get install gnupg curl
curl -fsSL https://www.mongodb.org/static/pgp/server-8.0.asc | \
sudo gpg -o /usr/share/keyrings/mongodb-server-8.0.gpg --dearmor
echo "deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/mongodb-server-8.0.gpg ] \
https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/8.0 multiverse" | \
sudo tee /etc/apt/sources.list.d/mongodb-org-8.0.list
sudo apt-get update
sudo apt-get install -y mongodb-org
sudo systemctl start mongod
sudo systemctl enable mongod
3. Configure MongoDB
Edit the MongoDB config file on both servers:
sudo nano /etc/mongod.conf
Set the following values:
net:
port: 27017
bindIp: 0.0.0.0
replication:
replSetName: "rs0"
security:
authorization: enabled
Then restart the MongoDB service:
sudo systemctl restart mongod
4. Initialize Replica Set
Log in to the Mongo shell on the primary:
mongosh
Run this setup:
rs.initiate({
_id: "rs0",
members: [
{ _id: 0, host: "primary-public-ip:27017", priority: 2 },
{ _id: 1, host: "secondary-public-ip:27017", priority: 1 }
]
})
Verify it using:
rs.status()
5. Create Admin User
On the primary:
db.createUser({
user: "adminUser",
pwd: "securePassword",
roles: [{ role: "root", db: "admin" }]
})
Reconnect with auth:
mongosh --host primary-public-ip:27017 -u adminUser -p securePassword --authenticationDatabase admin
6. Test Replication
Insert on primary:
use testdb
db.testCollection.insertOne({ message: "Testing replication", timestamp: new Date() })
Read from the secondary:
mongosh --host secondary-public-ip:27017 -u adminUser -p securePassword --authenticationDatabase admin
Enable read preference:
db.getMongo().setReadPref("secondaryPreferred")
use testdb
db.testCollection.find()
7. Simulate Failover
Stop MongoDB on the primary:
sudo systemctl stop mongod
Then, on the secondary, verify promotion:
rs.status() // This node should now be PRIMARY
Bring the primary back:
sudo systemctl start mongod
📝 8. Checklist / TL;DR
Here’s a quick reference summary to validate your setup:
✅ EC2s launched in two AWS regions
✅ MongoDB installed and configured
✅ Replica set initialized
✅ Authentication set up
✅ Replication verified
✅ Failover tested
✅ Conclusion
This guide demonstrates how to:
Set up a MongoDB replica set across AWS regions.
Secure it with authentication.
Test real-time replication and failover.
While this is a basic manual setup, production deployments may benefit from:
Private networking (e.g., VPC peering).
Automation via Terraform or Ansible.
Monitoring using MongoDB Ops Manager or Prometheus.
