[Deepsea-users] RFC: Experimental import of existing cluster

[Tim Serong]

Hi All,

We want DeepSea to be able to "import" existing ceph clusters, for
example if you've used ceph-deploy in the past, and want to migrate to
DeepSea.  I've implemented what you might call a rough outline of this
functionality at https://github.com/SUSE/DeepSea/commit/7a60715 (i.e.
the implementation is incomplete), and would appreciate feedback on the
approach in general.

There's more detail in the commit, but essentially you use it like so:

1) Install salt on every ceph node.
2) Run the first two DeepSea stages, plus my extra importer bit.
3) The importer checks what ceph services are running on all the minions
(mon, mds, osd, rgw), and generates a policy.cfg reflecting the
currently running cluser.
4) Now you can keep using DeepSea as usual.

WARNING: Do *NOT* try step 4 with the current code.  You WILL BREAK YOUR
CLUSTER.  I'm just trying to get feedback on whether there's any large
holes in the general shape of this thing (I had an earlier experiment
where I was interrogating ceph.conf to find the MONs, then realised I'd
end up having to talk to the cluster to ask it where the OSDs were, so I
decided that checking for running services was going to be simpler).

Thanks,

Tim
-- 
Tim Serong
Senior Clustering Engineer
SUSE
tserong at suse.com