Today, we have three different server parameters defined in sharding_cluster_parameters.idl. These are: shardedClusterCardinalityForDirectConns, addOrRemoveShardInProgress, and configServerReadPreferenceForCatalogQueries.

If we try to run getClusterParameter via the MongoS

db.adminCommand({ getClusterParameter: 'addOrRemoveShardInProgress' })

we will encounter an error, such as:

(MongoServerError[NoSuchKey]: Unknown server parameter: addOrRemoveShardInProgress

It happens the same if we try to update the cluster parameter (setClusterParameter) with a new value.

The root cause of this problem is that sharding_cluster_parameters.idl is only linked in MongoD, not in MongoS.