Today, a MongoD node can act as a router. This implies that MongoD should be able to run same functionalities as a MongoS does. There are some calls in the codebase that checks for ClusterRole::RouterServer in an exclusive mode, without considering that MongoD can act as a router and shard. That is, some of those calls may be outdated.

Goal

We need to revisit each exclusive check  for ClusterRole::RouterServer in serverGlobalParams.clusterRole to ensure that a MongoD acting as a router has the same behavior as a standalone MongoS.

References

• Example: serverGlobalParams.clusterRole.hasExclusively(ClusterRole::RouterServer)

Estimation

• User impact: Routing logic of MongoD may hit some invariant or assertion.
• Raw estimation: 5 man-days