How to setup mongo replicaset on Arch Linux?

Install bin version, mongo from source will compile even few hours

yay -S mongodb-bin

start / enable mongodb.service

sudo systemctl enable mongodb.service
sudo systemctl start mongodb.service

optionally check status

sudo systemctl status mongodb.service

connect to mongo

mongosh

By default replicaset is disabled. You can confirm it in mongosh

rs.status()
MongoServerError[NoReplicationEnabled]: not running with --replSet

Now time to change settings:

sudo nvim /etc/mongodb.conf

replace

#replcation:

by

replication:
  replSetName: "rs0"
  

restart mongo service

sudo systemctl restart mongodb.service

now you can see different error

rs.status()
MongoServerError[NotYetInitialized]: no replset config has been received

so lets init replicaset

rs.initiate()
{
  info2: 'no configuration specified. Using a default configuration for the set',
  me: '127.0.0.1:27017',
  ok: 1
}

Finally rs.status() works correctly.