MgrClient instances (such as those in the daemons, and those in every librados instance) open a session with ceph-mgr where they identify themselves by entity name and type. ceph-mgr sends a MgrConfigure message, which tells the client whether to both sending stats and how often. ceph-mgr also keeps a copy of the metadata (a la "ceph osd metadata...") for OSD and MDS daemons -- it loads all that up at startup, and then also freshens it when it sees a daemon restart or sees a new daemon. We would like to have something similar so that the mgr can be aware of the existence of other services like RGW gateways, RBD mirror services, perhaps also NFS gateways. The information about each daemon would at a minimum be its identity, type, and some static metadata. It might also include some dynamic state/health structure. The challenging part here is how to expose that to the various daemons, given that things like RGW are not known in advance to core Ceph and that they just consume the librados interface. It doesn't feel like a particularly natural thing for librados, but ultimately whatever we expose to rgw/rbd is de-facto librados, even if we put it in a different library or whatever. So far I've got as far as thinking we should have an extra call just in the C++ bindings that lets callers say "Hi, I'm a service not just a client, and here's a map of metadata", that they call one time between creating their RadosClient and connecting to the cluster. John -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
