[ClusterLabs] Pacemaker 1.1.15 - Release Candidate 4

Ken Gaillot kgaillot at redhat.com
Mon Jun 13 10:33:32 EDT 2016

On 06/13/2016 12:52 AM, Klaus Wenninger wrote:
> Sorry, I hadn't seen that you had replied (don't know why maybe I just
> had derived that from the time ;-) ).
> But I guess what I've written doesn't really contradict your answer ...
> Although it might make look us a little uncoordinated - anyway sorry
> again...
> Klaus

I thought we said essentially the same thing :-)

It's always good to get multiple perspectives anyway. It's easy for one
person to overlook something that's obvious to them, and even different
phrasing can be more understandable for various readers.

> On 06/12/2016 04:50 PM, Ken Gaillot wrote:
>> On 06/12/2016 07:28 AM, Ferenc Wágner wrote:
>>> Ken Gaillot <kgaillot at redhat.com> writes:
>>>> With this release candidate, we now provide three sample alert scripts
>>>> to use with the new alerts feature, installed in the
>>>> /usr/share/pacemaker/alerts directory.
>>> Hi,
>>> Is there a real reason to name these scripts *.sample?  Sure, they are
>>> samples, but they are also usable as-is, aren't they?
>> Almost as-is -- copy them somewhere, rename them without ".sample", and
>> mark them executable.
>> After some discussion, we decided that this feature is not mature enough
>> yet to provide the scripts for direct use. After we get some experience
>> with how users actually use the feature and the sample scripts, we can
>> gain more confidence in recommending them generally. Until then, we
>> recommend that people examine the script source and edit it to suit
>> their needs before using it.
>> That said, I think the SNMP script in particular is quite useful.
>> The log-to-file script is more a proof-of-concept that people can use as
>> a template. The SMTP script may be useful, but probably paired with some
>> custom software handling the recipient address, to avoid flooding a real
>> person's mailbox when a cluster is active.
>>>> The ./configure script has a new "--with-configdir" option.
>>> This greatly simplifies packaging, thanks much!
>>> Speaking about packaging: are the alert scripts run by remote Pacemaker
>>> nodes?  I couldn't find described which nodes run the alert scripts.
>>> From the mailing list discussions I recall they are run by each node,
>>> but this would be useful to spell out in the documentation, I think.
>> Good point. Alert scripts are run only on cluster nodes, but they
>> include remote node events. I'll make sure the documentation mentions that.
>>> Similarly for the alert guarrantees: I recall there's no such thing, but
>>> one could also think they are parts of transactions, thus having recovery
>>> behavior similar to the resource operations.  Hmm... wouldn't such
>>> design actually make sense?
>> We didn't want to make any cluster operation depend on alert script
>> success. The only thing we can guarantee is that the cluster will try to
>> call the alert script for each event. But if the system is going
>> haywire, for example, we may be unable to spawn a new process due to
>> some resource exhaustion, and of course the script itself may have problems.
>> Also, we wanted to minimize the script interface, and keep it
>> backward-compatible with crm_mon external scripts. We didn't want to add
>> an OCF-style layer of meta-data, actions and return codes, instead
>> keeping it as simple as possible for anyone writing one.
>> Since it's a brand new feature, we definitely want feedback on all
>> aspects once it's in actual use. If alert script failures turns out to
>> be a big issue, I could see maybe reporting them in cluster status (and
>> allowing that to be cleaned up).

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