Setup MongoDB Replica with Password Authentication in Ubuntu 20.04 LTS. (1 Master and 2 Secondary)

mongodb-cluster.txt

Setup MongoDB Replica with Password Authentication in Ubuntu 20.04 LTS.
(1 Master and 2 Secondary)

Overview
 1. Install MongoDB to all servers.
 2. Run rs.status() to check Replica set status.
 3. Generate Key file on any one server.
 4. Copy keyfile to all servers.
 5. Update conf file for keyfile, replicaset name and bind address on all servers.
 6. Restart MongoDB on servers.
 7. Run rs.initiate() on only one server.
 8. Create admin user on Primary server.
 9. Test Authentication in MongoDB.
 10. Login to MongoDB with Password.

Steps

1. Install MongoDB (Refrence taken from MongoDB official Documentaion for version MongoDB 5.0 Community Edition).

	sudo apt-get install gnupg
	wget -qO - https://www.mongodb.org/static/pgp/server-5.0.asc | sudo apt-key add -
	echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/5.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-5.0.list
	sudo apt-get update
	sudo apt-get install -y mongodb-org
	sudo systemctl start mongod
	sudo systemctl enable mongod


2. On any one instance generate keyfile.
	openssl rand -base64 756 > /var/lib/mongodb/keyfile
	chmod 400 /var/lib/mongodb/keyfile
	chown mongodb:mongodb /var/lib/mongodb/keyfile

3. Copy keyfile to all servers
	rsync -av /var/lib/mongodb/keyfile root@ip-of-your-instance:/var/lib/mongodb
	(for rsync to work make sure serverss able to connect with each other by adding ssh key in authorized_keys.)

4. Update conf file for keyfile, password Auth., replicaset name and bind address on all servers
   file location: /etc/mongod.conf
   a. update bind address
   		net:
  		  bindIp: 0.0.0.0
  		(I'm binding to all network interfaces for demo purpose. In production bind to only required interface)

   b. update security
   		security:
          keyFile: /var/lib/mongodb/keyfile

   c. update replica set name
   		replication:
  		  replSetName: "rs0"

5. Restart mongoDB
	sudo systemctl restart mongod.service

6. Run rs.initiate() on only one server.
   type mongo in terminal to get MongoDB shell
   type below command to initialize cluster.
   rs.initiate(
   {
    	_id : 'rs0',
    	members: [
      		{ _id : 0, host : "ip-of-instance-1:27017" },
      		{ _id : 1, host : "ip-of-instance-2:27017" },
      		{ _id : 2, host : "ip-of-instance-3:27017" }
    		]
  		}
	);

7. Run rs.status() to check Replica set status.
   you will get list of members with their status like which members are Primary and secondary.


8. Create Admin user
	db.createUser(
		{
			user: "Admin",pwd: "myNewPassword",
			roles: [ { role: 'root', db: 'admin' } ]
		}
	);

9. Test Authentication in MongoDB.
   run rs.status() it will give you an errmsg with "ommand replSetGetStatus requires authentication"

10. Login to MongoDB with Password
	sample url to login is: 
		mongo "mongodb://<username>:<password>@<host>:<port>/<dbName>?replicaSet=<replicaSetName>"
	
	in our case url should be:
		mongo "mongodb://Admin:myNewPassword@ip-of-instance-1:27017,ip-of-instance-2:27017,ip-of-instance-3:27017/admin/?replicaSet=rs0"

	After login type rs.status() to check status of cluster.