[ClusterLabs] Booth fail-over conditions

[Dejan Muhamedagic]

Hi,

On Mon, Apr 16, 2018 at 01:22:08PM +0200, Kristoffer Grönlund wrote:
> Zach Anderson <zpanderson88 at gmail.com> writes:
> 
> >  Hey all,
> >
> > new user to pacemaker/booth and I'm fumbling my way through my first proof
> > of concept. I have a 2 site configuration setup with local pacemaker
> > clusters at each site (running rabbitmq) and a booth arbitrator. I've
> > successfully validated the base failover when the "granted" site has
> > failed. My question is if there are any other ways to configure failover,
> > i.e. using resource health checks or the like?

You can take a look at "before-acquire-handler" (quite a mouthful
there). The main motivation was to add an ability to verify that
some other conditions at _the site_ are good, perhaps using
environment sensors, say to measure temperature, or if the
aircondition works, or such.

Nothing stopping you from doing there a resource health check,
but it could probably be deemed as something on a rather
different "level".

> 
> Hi Zach,
> 
> Do you mean that a resource health check should trigger site failover?
> That's actually something I'm not sure comes built-in..

There's nothing really specific about a resource, because booth
knows nothing about resources. The tickets are the only way it
can describe the world ;-)

Cheers,

Dejan

> though making a
> resource agent which revokes a ticket on failure should be fairly
> straight-forward. You could then group your resource which the ticket
> resource to enable this functionality.
> 
> The logic in the ticket resource ought to be something like "if monitor
> fails and the current site is granted, then revoke the ticket, else do
> nothing". You would probably want to handle probe monitor invocations
> differently. There is a ocf_is_probe function provided to help with
> this.
> 
> Cheers,
> Kristoffer
> 
> > Thanks!
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> -- 
> // Kristoffer Grönlund
> // kgronlund at suse.com
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