[ClusterLabs Developers] Proposed future feature: multiple notification scripts

[Digimer]

On 03/12/15 07:40 PM, Andrew Beekhof wrote:
> 
>> On 3 Dec 2015, at 4:14 PM, Digimer <lists at alteeve.ca> wrote:
>>
>> On 02/12/15 06:23 PM, Ken Gaillot wrote:
>>> This will be of interest to cluster front-end developers and anyone who
>>> needs event notifications ...
>>>
>>> One of the new features in Pacemaker 1.1.14 will be built-in
>>> notifications of cluster events, as described by Andrew Beekhof on That
>>> Cluster Guy blog:
>>> http://blog.clusterlabs.org/blog/2015/reliable-notifications/
>>>
>>> For a future version, we're considering extending that to allow multiple
>>> notification scripts, each with multiple recipients. This would require
>>> a significant change in the CIB. Instead of a simple cluster property,
>>> our current idea is a new configuration section in the CIB, probably
>>> along these lines:
>>>
>>> <configuration>
>>>   <!-- usual crm_config etc. here -->
>>>
>>>   <!-- this is the new section -->
>>>   <notifications>
>>>
>>>      <!-- each script would be in a notify element -->
>>>      <notify id="notify-1" path="/my/script.sh" timeout="30s">
>>>
>>>         <recipient id="recipient-1" value="me at example.com" />
>>>         <!-- etc. for multiple recipients -->
>>>
>>>      </notify>
>>>
>>>      <!-- etc. for multiple scripts -->
>>>
>>>   </notifications>
>>> </configuration>
>>>
>>>
>>> The recipient values would be passed to the script as command-line
>>> arguments (ex. "/my/script.sh me at example.com").
>>>
>>> For backward compatibility, the (brand new!) notification-agent and
>>> notification-recipient cluster properties would be kept as deprecated
>>> shortcuts for a single notify script and recipient.
>>>
>>> Also for backward compatibility, the first recipient would be passed to
>>> the script as the CRM_notify_recipient environment variable.
>>>
>>> This proposal came about because the new notification capability has
>>> turned out to be useful enough that people sometimes want to use it for
>>> multiple purposes, e.g. email an administrator, and notify some software
>>> that an event occurred. Trying to fit unrelated actions in one
>>> notification script (or a script that calls multiple other scripts) has
>>> obvious pitfalls, so this would make it easier on sysadmins.
>>>
>>> Another advantage will be a configurable timeout (1.1.14 will have a
>>> hardcoded 5-minute timeout for notification scripts).
>>
>> In ScanCore, we handled this by delivering to a locally configured
>> postfix instance. This handles queueing and delivery without the
>> higher-level app needing to worry about it.
>>
>> (unless I am misunderstanding "timeout" in this context…)
> 
> how long the script can take

That makes a lot more sense. I guess I was expecting it to call the
script and background it, rather than waiting for it to exit. Thinking
about it though, that could go badly in a hurry. :)

>>> The crm_attribute command and the various cluster front-ends would need
>>> to be modified to handle the new configuration syntax.
>>>
>>> This is all in the idea stage (development is still a ways off), so any
>>> comments, suggestions, criticisms, etc. are welcome.
>>
>> Would it be up to the called script to craft the message,
> 
> yes because pacemaker has (and wants) no knowledge of the transport (SMS, vs email vs. snmp etc)

As Ken explained, ya, I see now how it will work.

>> or would the
>> message be generated by pacemaker? If the later; How would you handle
>> internationalization?
>>
>> Event-driven alerts is a fantastic idea. :D
>>
>> -- 
>> Digimer
>> Papers and Projects: https://alteeve.ca/w/
>> What if the cure for cancer is trapped in the mind of a person without
>> access to education?
>>
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-- 
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?