After connecting to the mongos instance, you can add shards to sharding. Basically, you can add two types of endpoints to the mongos as a shard; a replica set or a standalone mongod instance.
MongoDB has a sh namespace and a function called addShard(), which is used to add a new shard to an existing sharding network. Here is the example of a command to add a new shard. This is shown in the following screenshot:
To add a replica set to mongos you should follow this scheme:
setname/server:port
For instance, if you have a replica set with the name of rs1, hostname mongod1.replicaset.com, and port number 27017, the command will be as follows:
sh.addShard("rs1/mongod1.replicaset.com:27017")
Using the same function, we can add standalone mongod instances. So, if we have a mongod instance with the hostname mongod1.sharding.com listening on port 27017, the command will be as follows:
sh.addShard("mongod1.sharding.com:27017")
