[ClusterLabs] Pacemaker alert framework
kgaillot at redhat.com
Fri Jul 6 10:20:41 EDT 2018
On Fri, 2018-07-06 at 15:58 +0200, Klaus Wenninger wrote:
> On 07/06/2018 03:41 PM, Ian Underhill wrote:
> > requirement:
> > when a resource fails perform an actionm, run a script on all nodes
> > within the cluster, before the resource is relocated. i.e.
> > information gathering why the resource failed.
> Have in mind that trying to run a script on all nodes in the cluster
> proceeding is a delicate issue because not being able to run it on
> node might prevent relocation and thus availability.
> Of course this largely depends on how it is implemented - just wanted
> to raise attention.
> > what I have looked into:
> > 1) Use the monitor call within the resource to SSH to all nodes,
> > again SSH config needed.
> > 2) Alert framework : this only seems to be triggered for nodes
> > involved in the relocation of the resource. i.e. if resource moves
> > from node1 to node 2 node 3 doesnt know. so back to the SSH
> > solution :(
> Alerts are designed not to block anything (no other alerts as well)
> so the alert-agents are
> just called on nodes that anyway already have to do with that very
> > 3) sending a custom alert to all nodes in the cluster? is this
> > possible? not found a way?
> > only solution I have:
> > 1) use SSH within an alert monitor (stop) to SSH onto all nodes to
> > perform the action, the nodes could be configured using the alert
> > monitors recipients, but I would still need to config SSH users and
> > certs etc.
> > 1.a) this doesnt seem to be usable if the resource is
> > relocated back to the same node, as the alerts start\stop are run
> > at the "same time". i.e I need to delay the start till the SSH has
> > completed.
> > what I would like:
> > 1) delay the start\relocation of the resource until the information
> > from all nodes is complete, using only pacemaker behaviour\config
> > any ideas?
> Not 100% sure of what what your exact intention is ...
> You could experiment with a clone that depends on the running
> instance and
> use the stop of that to trigger whatever you need.
> Not sure but I'd expect that pacemaker would tear down all clone
> before it relocates your resource.
Yes, that sounds like a good solution. See clone notifications:
You could even combine everything into a single custom resource agent
for use as a master/slave resource, where the master is the only
instance that actually runs the resource, and the slaves just act on
> > Thanks
> > /Ian.
Ken Gaillot <kgaillot at redhat.com>
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