[ClusterLabs] Colocation of a primitive resource with a clone with limited copies

[Vladislav Bogdanov]

20.04.2017 23:16, Jan Wrona wrote:
> On 20.4.2017 19:33, Ken Gaillot wrote:
>> On 04/20/2017 10:52 AM, Jan Wrona wrote:
>>> Hello,
>>>
>>> my problem is closely related to the thread [1], but I didn't find a
>>> solution there. I have a resource that is set up as a clone C restricted
>>> to two copies (using the clone-max=2 meta attribute||), because the
>>> resource takes long time to get ready (it starts immediately though),
>> A resource agent must not return from "start" until a "monitor"
>> operation would return success.
>>
>> Beyond that, the cluster doesn't care what "ready" means, so it's OK if
>> it's not fully operational by some measure. However, that raises the
>> question of what you're accomplishing with your monitor.
> I know all that and my RA respects that. I didn't want to go into
> details about the service I'm running, but maybe it will help you
> understand. Its a data collector which receives and processes data from
> a UDP stream. To understand these data, it needs templates which
> periodically occur in the stream (every five minutes or so). After
> "start" the service is up and running, "monitor" operations are
> successful, but until the templates arrive the service is not "ready". I
> basically need to somehow simulate this "ready" state.

If you are able to detect that your application is ready (it already 
received its templates) in your RA's monitor, you may want to use 
transient node attributes to indicate that to the cluster. And tie your 
vip with such an attribute (with location constraint with rules).

http://clusterlabs.org/doc/en-US/Pacemaker/1.1/html/Pacemaker_Explained/_using_rules_to_determine_resource_location.html#_location_rules_based_on_other_node_properties

Look at pacemaker/ping RA for attr management example.

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