[ClusterLabs] Antw: Re: Command to show location constraints?

[Ulrich Windl]

>>> Jan Pokorný <jpokorny at redhat.com> schrieb am 28.08.2019 um 10:03 in
Nachricht
<20190828080347.GA9493 at redhat.com>:
> On 27/08/19 09:24 ‑0600, Casey & Gina wrote:
>> Hi, I'm looking for a way to show just location constraints, if they
>> exist, for a cluster.  I'm looking for the same data shown in the
>> output of `pcs config` under the "Location Constraints:" header, but
>> without all the rest, so that I can write a script that checks if
>> there are any set.
>> 
>> The situation is that sometimes people will perform a failover with
>> `pcs resource move ‑‑master <resource>`, but then forget to follow
>> it up with `pcs resource clear <resource>`, and then it causes
>> unnecessary failbacks later.  As we never want to have any
>> particular node in the cluster preferred for this resource, I'd like
>> to write a script that can automatically check for any location
>> constraints being set and either alert or clear it automatically.
> 
> One could also think of "crm_resource ‑‑clear ‑‑dry‑run" that doesn't
> exist yet.  Please, file a RFE with https://bugs.clusterlabs.org if
> this would be useful.


Thinking about it: Location constraints can have an expire timestamp, but they
don't have a creation timestamp (AFAIK). This the first step in automatically
cleaning up location constraints that don't have an expiration time set would
be adding a creation time stamp.
The next step would be a definition of a "maximum location constraint
lifetime",
and finally actual code that removes location constraints that exceeded their
lifetime.

Thinking about it: There may be a more pleasing solution for the current code
base: Define a maximum lifetime for any migration constraint, and use that if
the user did not specify one.
(The constrains would still linger around, but would not have an effect any
more.)

Regards,
Ulrich

> 
> ‑‑ 
> Jan (Poki)