Re: Extra daemons/servers reporting to mgr

[Matt Benjamin <mbenjamin@redhat.com>]

The nfs gateways are clients of either libcephfs or librgw, so in the first instance, I would say that librgw, for example, which creates an RGW instance, should be the client of this API.

Matt

----- Original Message -----
> From: "Daniel Gryniewicz" <dang@redhat.com>
> To: "John Spray" <jspray@redhat.com>, "Ceph Development" <ceph-devel@vger.kernel.org>
> Sent: Monday, June 12, 2017 10:14:02 AM
> Subject: Re: Extra daemons/servers reporting to mgr
> 
> On 06/11/2017 08:04 AM, John Spray wrote:
> > 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.
> >
> 
> This seems fine, but if we want NFS gateways, too, then a C API would be
> helpful.
> 
> Daniel
> 
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-- 
Matt Benjamin
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