[ClusterLabs] colocate Redis - weird

[Ken Gaillot]

On Wed, 2023-12-20 at 11:16 +0100, lejeczek via Users wrote:
> 
> 
> On 19/12/2023 19:13, lejeczek via Users wrote:
> > hi guys,
> > 
> > Is this below not the weirdest thing?
> > 
> > -> $ pcs constraint ref PGSQL-PAF-5435
> > Resource: PGSQL-PAF-5435
> >   colocation-HA-10-1-1-84-PGSQL-PAF-5435-clone-INFINITY
> >   colocation-REDIS-6385-clone-PGSQL-PAF-5435-clone-INFINITY
> >   order-PGSQL-PAF-5435-clone-HA-10-1-1-84-Mandatory
> >   order-PGSQL-PAF-5435-clone-HA-10-1-1-84-Mandatory-1
> >   colocation_set_PePePe

Can you show the actual constraint information (resources and scores)
for the whole cluster? In particular I'm wondering about that set.

> > 
> > Here Redis master should folow pgSQL master.
> > Which such constraint:
> > 
> > -> $ pcs resource status PGSQL-PAF-5435
> >   * Clone Set: PGSQL-PAF-5435-clone [PGSQL-PAF-5435] (promotable):
> >     * Promoted: [ ubusrv1 ]
> >     * Unpromoted: [ ubusrv2 ubusrv3 ]
> > -> $ pcs resource status REDIS-6385-clone
> >   * Clone Set: REDIS-6385-clone [REDIS-6385] (promotable):
> >     * Unpromoted: [ ubusrv1 ubusrv2 ubusrv3 ]
> > 
> > If I remove that constrain:
> > -> $ pcs constraint delete colocation-REDIS-6385-clone-PGSQL-PAF-
> > 5435-clone-INFINITY
> > -> $ pcs resource status REDIS-6385-clone
> >   * Clone Set: REDIS-6385-clone [REDIS-6385] (promotable):
> >     * Promoted: [ ubusrv1 ]
> >     * Unpromoted: [ ubusrv2 ubusrv3 ]
> > 
> > and ! I can manually move Redis master around, master moves to each
> > server just fine.
> > I again, add that constraint:
> > 
> > -> $ pcs constraint colocation add master REDIS-6385-clone with
> > master PGSQL-PAF-5435-clone
> > 
> > and the same...
> > 
> > 
>  What there might be about that one node - resource removed, created
> anew and cluster insists on keeping master there.
> I can manually move the master anywhere but if I _clear_ the
> resource, no constraints then cluster move it back to the same node.
> 
> I wonder about:  a) "transient" node attrs & b) if this cluster is
> somewhat broken.
> On a) - can we read more about those somewhere?(not the
> code/internals)
> thanks, L.
> 

Transient attributes are the same as permanent ones except they get
cleared when a node leaves the cluster.

The constraint says that the masters must be located together, but they
each still need to be enabled on a given node with either a master
score attribute (permanent or transient) or a location constraint.
-- 
Ken Gaillot <kgaillot at redhat.com>