[ClusterLabs] Coming in Pacemaker 1.1.17: container bundles

[Jan Pokorný]

On 03/04/17 09:47 -0500, Ken Gaillot wrote:
> On 04/03/2017 02:12 AM, Ulrich Windl wrote:
>>>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 01.04.2017 um 00:43 in Nachricht
>> <981d420d-73b2-3f24-a67c-e9c66dafb48f at redhat.com>:
>> 
>> [...]
>>> Pacemaker 1.1.17 introduces a new type of resource: the "bundle". A
>>> bundle is a single resource specifying the Docker settings, networking
>>> requirements, and storage requirements for any number of containers
>>> generated from the same Docker image.
>> 
>> I wonder: Is a "bundle" just a kind of special "group template"? It
>> looks as if I could do it with a group also, but would have to
>> write a bite more to get it configured. Did I miss something?
> 
> With a group, you could reproduce most of this functionality, though it
> would be more verbose: you'd need to configure ocf:heartbeat:docker,
> ocf:heartbeat:IPaddr2, and ocf:pacemaker:remote resources, plus a
> primitive for your service, as well as constraints that restrict the
> primitive to the guest node and prevent any other resource from running
> on the guest node.
> 
> However, this can do something that a group can't: launch multiple
> instances of a single container image, while associating floating IPs
> and storage mappings specific to each replica. This puts it somewhere
> between a group and a specialized form of clone.

In that case, wouldn't it be more systemic to factor any generic
clone/master-like controls (replicas, replicas-per-host, masters) out
of <docker> so it can be reused seemlessly when switching to other
possible containerization backends in the future?

> Also, it will be shown differently in the cluster status, which is
> helpful.

-- 
Jan (Poki)
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