[ClusterLabs] Pacemaker in puppet with cib.xml?

Stephano-Shachter, Dylan dstathis at seas.harvard.edu
Thu Jul 21 16:02:32 EDT 2016


So I should be using "pcs cluster cib > file" to get the config and then
"pcs cluster cib-push --config file" to push it?

Also I shouldn't have to add --config to the pcs -f commands right?

On Thu, Jul 21, 2016 at 3:51 PM, Jan Pokorný <jpokorny at redhat.com> wrote:

> On 21/07/16 13:52 -0500, Ken Gaillot wrote:
> > On 07/21/2016 01:35 PM, Stephano-Shachter, Dylan wrote:
> >> I want to put the pacemaker config for my two node cluster in puppet
> >> but, since it is just one cluster, it seems overkill to use the corosync
> >> module. If I just have puppet push cib.xml to each machine, will that
> >> work? To make changes, I would just use pcs to update things and then
> >> copy cib.xml back to puppet. I am not sure what happens when you change
> >> cib.xml while the cluster is running. Is it safe?
> >
> > No, pacemaker checksums the CIB and won't accept a file that isn't
> > properly signed. Also, the cluster automatically synchronizes changes
> > made to the CIB across all nodes, so there is no need to push changes
> > more than once.
> >
> > Since you're using pcs, the update process could go like this:
> >
> >   # Get the current configuration:
> >   pcs cluster cib --config > cib-new.xml
>
> As I feel guilty for contributing to this misconception with clufter
> "pcs commands" output at one point (also see
> https://bugzilla.redhat.com/1328078; still part of the blame
> is in pcs I believe: https://bugzilla.redhat.com/1328066),
> something has just started screaming in me:
>
> DO NOT USE pcs cluster cib WITH --config LIKE SUGGESTED, BUT RATHER:
>
>     pcs cluster cib > cib-new.xml
>
> >   # Make changes:
> >   pcs -f cib-new.xml <whatever-command-you-want>
> >   <etc.>
>
> ...as otherwise the modifications like this ^ would fail.
>
> >   # Upload the configuration changes to the cluster:
> >   pcs cluster cib-push --config cib-new.xml
>
> Note that with cib-push, --config is OK, moreover it's vital as you
> really don't want to propagate stale status section and what not
> when changing modifying configuration.
>
> Yes, it's counterintuitive to have this asymmetry and it could be
> made to work with some added effort at the side of pcs with
> the original, disapproved, sequence as-is, but that's perhaps
> sound of the future per the referenced pcs bug.
> So take this idiom as a rule of thumb not to be questioned
> any time soon.
>
> > Using "--config" is important so you only work with the configuration
> > section of the CIB, and not the dynamically determined cluster
> > properties and status.
>
> (This, apparently, justifies just the cib-push use.)
>
> >
> > The first and last commands can be done on any one node, with the
> > cluster running. The "pcs -f" commands can be done anywhere/anytime.
>
> --
> Jan (Poki)
>
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