[Pacemaker] crmsh: New syntax for location constraints, suggestions / comments

Lars Marowsky-Bree lmb at suse.com
Fri Dec 13 05:57:31 EST 2013

On 2013-12-13T11:46:05, Kristoffer Grönlund <kgronlund at suse.com> wrote:

> This worries me as well, however the current syntax for constraints is
> confusing and error-prone.

Right. At least the { } would make it clear to users that it's now a
resource set and not merely more than 2 in the same sequence.

> It would be great to be able to do something
> to make this easier to use, but exactly what it would be is hard to
> say. Making a change that would silently invert the functionality of
> existing configurations is, I agree, not a good idea. However, maybe it
> would be acceptable if a "version: 2" header is required in the
> document to enable the new syntax?

Yeah. It's one of those "I wish we had done it differently" moments, but
I guess we're stuck here.

But another thing we discussed is hiding ids for dependencies by
default, since except for resource objects they really don't matter in
99% of the cases. That would condense the configuration significantly.

> Yet another option is to come up with some entirely new construct to
> supplement colocation and order which does what I think most people
> intuitively expects by default, which is enforces both colocation and
> ordering, so that 'foo depends on bar' means foo will start after bar,
> and only where bar is running.

chain a b c

(specifying the id or a score would be optional; score would default to

I'm all in favor. ;-) I'd love it if this had backend support (so pcs
could use it too), but if we can't get it, we may just merge colocation
and order internally to crmsh.


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