6 Easy Steps to Configure MongoDB Replication Set

In this tutorial we'll create a 3 nodes cluster, where the first serves as a primary node, and second as a failover node and the third as an Arbiter

1. Setup Mongo and Set a Configuration File
In all the 3 servers adjust the configuration file /etc/mongod.conf:
#Select your replication set name

replSet=[replication_set_name]
#Select the replication log size

oplogSize=1024

replication:
   oplogSizeMB: 
   replSetName: 

Disable the bind_ip parameter to avoid binding to only 127.0.0.1 interface

#bind_ip

2. Restart All 3 mongod Daemons

> sudo service mongod restart

3. Create an Initial Configuration on the Primary
Login to the primary mongo and create an initial configuration. Please notice to use the private IP and not the loopback address (127.0.0.1):
> mongo

Primary> cfg = {"_id" : "[replication_set_name]", "members" : [{"_id" : 0,"host" : "[Primary_Host_IP]:27017"}]}

Primary> rs.initiate(cfg);

4. Add the Failover Instance to the Replication Set

Primary> rs.add("[Failover_Host_IP]:27017")

5. Add the Arbier Instance to the Replication Set

Primary> rs.addArb("[Arbiter_Host_IP]:27017")

6. Verify the Replication Set Status
Primary> rs.status()

Bottom Line
I wish every data cluster setup was as easy as a setup of a MongoDB replication set.

Keep Performing,
Moshe Kaplan