[Pacemaker] pacemaker-remote container as a clone resource

[Patrick Hemmer]

*From:* Andrew Beekhof <andrew at beekhof.net>
*Sent:* 2014-08-31 23:16:10 EDT
*To:* The Pacemaker cluster resource manager <pacemaker at oss.clusterlabs.org>
*Subject:* Re: [Pacemaker] pacemaker-remote container as a clone resource

> On 1 Sep 2014, at 12:41 pm, Patrick Hemmer <pacemaker at feystorm.net> wrote:
>
>> From: Andrew Beekhof <andrew at beekhof.net>
>> Sent: 2014-08-31 19:57:43 EDT
>> To: The Pacemaker cluster resource manager <pacemaker at oss.clusterlabs.org>
>> Subject: Re: [Pacemaker] pacemaker-remote container as a clone resource
>>
>>> On 31 Aug 2014, at 6:09 pm, Patrick Hemmer <pacemaker at feystorm.net>
>>>  wrote:
>>>
>>>
>>>> I'm interested in creating a resource that will control host containers running pacemaker-remote. The catch is that I want this resource to be a clone, so that if I want more containers, I simply increase the `clone-max` property.
>>>>
>>> What kind of container?
>> Well I would hope the solution is generic enough to work with any container. But in my specific case, EC2 instances. Plus maybe docker for development work.
>>
>>> Most development was done with VirtualMachine which needs a unique name anyway (ie. cant be cloned).
>> With EC2 (and docker), you create an instance/container and the name & address is returned after creation.
> Thats going to be challenging then.
> Since there is no way to know which containers are allowed to be attempting a connection or even which ones match up to the implicit connection managers we have started.
That was the reason for my thought about setting an attribute on the
clone child from within the resource agent. The resource agent would
start the container, the container management service would respond with
the address, and the resource agent would call `crm_attribute` on itself
(the clone child) to set the `remote-node` property to the address of
the container (like master/slave resource agents do for setting scores).

Though I don't follow on what you mean on "which containers are allowed
to be attempting a connection". The pacemaker-remote connection is
initiated by the host, not the remote. So no container should be
connecting, and the resource agent will instruct the host who it should
be connecting to.

> I assume all of these containers are doing the same thing?
Basically yes. They'll all be capable of running resources as instructed
by pacemaker.

>
>>> Interesting concept though, I'm sure we can figure out some way to get it done.
>>>
>>>
>>>> The problem is that the `remote-node` meta parameter is set on the clone resource, and not the children. So I can't see a way to tell pacemaker the address of all the clone children containers that get created.
>>>> The only way I can see something like this being possible is if the resource agent set an attribute on the clone child when the child was started.
>>>>
>>>> Is there any way to accomplish this? Or will I have to create separate resources for every single container? If this isn't possible, would this be considered as a future feature?
>>>>
>>>> Thanks
>>>>
>>>> -Patrick
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>
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