Enabling mongodb replica set

Configuration

Add this to your mongo configuration file (/etc/mongod.conf):

replication:
  replSetName: "rs0"

or just execute the command below:

printf "\nreplication:\n  replSetName: \"rs0\"\n" | sudo tee -a /etc/mongod.conf

sudo service mongod restart

mongo --eval 'rs.initiate({_id : "rs0", members: [{_id: 0, host: "127.0.0.1:27017"}]})'