[ClusterLabs] CIB daemon up and running

[Jan Pokorný]

Hello Rohit,

On 31/07/18 05:03 +0000, Rohit Saini wrote:
> After "pcs cluster start", how would I know if my CIB daemon has
> come up and is initialized properly.
> Currently I am checking output of "cibadmin -Q" periodically and
> when I get the output, I consider CIB daemon has come up and
> initialized.
> 
> Is there anything better than this? I am looking for some
> optimizations with respect to above.

The natural question here: what's your wider goal here?

Do you want to establish the connection with CIB (the daemon
got renamed to pacemaker-based since 2.0) as soon as it's possible
as an readiness indication for your scripting/application on top
of pacemaker?  I actually suspect we are back in automation waters
(Ansible?)...  Then, users list might be actually more suitable
venue to discuss this (CC'd).

The client/server arrangement of local inter-process communication
won't hardly allow for anything better than polling at this time,
with an exception being a slight possibly of using inotify to hook
at when /dev/shm/qb-cib_* file gets created.  That would, however,
rely on some kind of an implementation detail, which is indeed
discouraged, as it's generally a moving target.

If there's a demand, we could possibly add a DBus interface and
emit signals about events like these -- that might also alleviate
busy waiting/polling (or unreliable guarantees) in crm/pcs when
it comes to cases like this as well, I guess.  Or is there any
better idea how to move towards fully event-driven system?

-- 
Nazdar,
Jan (Poki)
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