[ClusterLabs] Does anyone use clone instance constraints from pacemaker-next schema?

Jehan-Guillaume de Rorthais jgdr at dalibo.com
Wed Jan 10 19:16:16 EST 2018

On Wed, 10 Jan 2018 12:23:59 -0600
Ken Gaillot <kgaillot at redhat.com> wrote:
> My question is: has anyone used or tested this, or is anyone interested
> in this? We won't promote it to the default schema unless it is tested.
> My feeling is that it is more likely to be confusing than helpful, and
> there are probably ways to achieve any reasonable use case with
> existing syntax.

For what it worth, I tried to implement such solution to dispatch mulitple
IP addresses to slaves in a 1 master 2 slaves cluster. This is quite time
consuming to wrap its head around sides effects with colocation, scores and
stickiness. My various tests shows everything sounds to behave correctly now,
but I don't feel really 100% confident about my setup.

I agree that there are ways to achieve such a use case with existing syntax.
But this is quite confusing as well. As instance, I experienced a master
relocation when messing with a slave to make sure its IP would move to the
other slave node...I don't remember exactly what was my error, but I could
easily dig for it if needed.

I feel like it fits in the same area that the usability of Pacemaker. Making it
easier to understand. See the recent discussion around the gocardless war story.

My tests was mostly for labs, demo and tutorial purpose. I don't have a
specific field use case. But if at some point this feature is promoted
officially as preview, I'll give it some testing and report here (barring the
fact I'm actually aware some feedback are requested ;)).

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