mongodb localhost replicasetup - mongodb

Question

I want to setup a replicasetup in my local machine,I am using to instances of mongodb(mongod1.conf,mongod2.conf), rs initiated mongo1 on port 27018 and i want to add the members to 27018 , rs.add('ThinkPad-X230:27019') it is throwing an error called
commands :
mongod --replSet Replicaset1 --dbpath home/data --port 27018
mongo --port 27018
>> rs.initiate()
>> rs.add("ThinkPad-X230:27019")
mongod --dbpath home/data2 --port 27019
mongo --port 27019
i have checked the db.serverStatus().host in 27019 port and adding host name "ThinkPad-X230:27019" to rs.add() members it is throwing the error.
{
"ok" : 0,
"errmsg" : "Either all host names in a replica set configuration must be localhost references, or none must be; found 1 out of 2",
"code" : 103,
"codeName" : "NewReplicaSetConfigurationIncompatible",
"operationTime" : Timestamp(1568943205, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1568943205, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

Answer 1

As you started your first instance of mongod with --replSet Replicaset1 option, it is configured to be a part of Replicaset1 replica set.
And when you initialised the replica set, this instance was added to the replica set as a member. Below is the output snippet of rs.status()
{
"_id" : 0,
"name" : "localhost:27018",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 228,
"optime" : {
"ts" : Timestamp(1569751005, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-09-29T09:56:45Z"),
"electionTime" : Timestamp(1569750830, 2),
"electionDate" : ISODate("2019-09-29T09:53:50Z"),
"configVersion" : 3,
"self" : true
}
As you can see the name of the member is "localhost:2018".
So, when you try to add another member to this replica set as rs.add('ThinkPad-X230:27019'), it gives you the following error which is a valid error to be thrown, as one member is "localhost:2018" and another which you are trying to add is "ThinkPad-X230:27019" and both must be localhost.
"errmsg" : "Either all host names in a replica set configuration must be localhost references, or none must be; found 1 out of 2"
Try to add the member using the following command,
rs.add("localhost:27019")
And it will be added successfully.