[Pacemaker] Enable remote monitoring

[Lars Marowsky-Bree]

On 2012-11-09T11:04:15, Andrew Beekhof <andrew at beekhof.net> wrote:

> So I was just explaining the problem and context to David... his
> comment was "aren't these just unmanaged resources and some
> constraints?".

They can even be managed - the start would be a "while ! monitor ; sleep
1 ; done" fake, and similar for stop. And then you could see the
services wink in and out too.

> Of course its slightly more complex than that, but what if we made a
> "container" type in the PE?
> Something analogous to groups (ie. a parent with N children) but
> possibly without the internal ordering.

Yes. We thought about a new meta attribute to a group too.

> Conceptually its also a little closer to how the admin probably thinks
> of the system and we'd make the semantics be that you don't start
> monitoring the children until the parent is fully up and any failures
> are a failure of the parent (optional?).

Right, the last bit is the interesting one. Basically, an ordering
dependency which works the other way around for "monitor" than it works
for start/stop, and that could be turned on for the group via the
special attribute.

There is one downside that I've not yet been able to circumvent:
templates. The monitor op would have allowed one to write something
like:

rsc_template vm-web ocf:heartbeat:VirtualDomain ... \
	op monitor nagios:http ...

With the container syntax, this will look like:

primitive vm-web-1 ocf:heartbeat:VirtualDomain ...
primitive vm-web-1-monitor nagios:http ...
group container-vm-web-1 vm-web-1 vm-web-1-monitor \
	meta container="vm-web-1"

For each VM. i.e., the CIB would blow up considerably more. But that
might be acceptable and solved later ...?


Regards,
    Lars

PS: any UI tool could render "group ... meta container='vm-web-1'" as
"container ..." directly, too. Just thinking this might make the XML
neater.

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