[ClusterLabs] Antw: Re: Antw: [EXT] Re: Q: rulke-based operation pause/freeze?

[Ulrich Windl]

>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 06.03.2020 um 16:00 in
Nachricht
<bed62f6d2c3d92d09f7306f4108195ccc6f1b99f.camel at redhat.com>:
> On Fri, 2020‑03‑06 at 08:19 +0100, Ulrich Windl wrote:
>> > > > Ondrej <ondrej‑clusterlabs at famera.cz> schrieb am 06.03.2020 um
>> > > > 01:45 in
>> 
>> Nachricht
>> <
>>
7499_1583455563_5E619D4B_7499_1105_1_2a18c389‑059e‑cf6f‑a840‑dec26437fdd1 at famer
>> .cz>:
>> > On 3/5/20 9:24 PM, Ulrich Windl wrote:
>> > > Hi!
>> > > 
>> > > I'm wondering whether it's possible to pause/freeze specific
>> > > resource 
>> > 
>> > operations through rules.
>> > > The idea is something like this: If your monitor operation needes
>> > > (e.g.) 
>> > 
>> > some external NFS server, and thst NFS server is known to be down,
>> > it seems
>> > better to delay the monitor operation until NFS is up again, rather
>> > than 
>> > forcing a monitor timeout that will most likely be followed by a
>> > stop 
>> > operation that will also time out, eventually killing the node
>> > (which has no
>> > problem itself).
>> > > 
>> > > As I guess it's not possible right now, what would be needed to
>> > > make this 
>> > 
>> > work?
>> > > In case it's possible, how would an example scenario look like?
>> > > 
>> > > Regards,
>> > > Ulrich
>> > > 
>> > 
>> > Hi Ulrich,
>> > 
>> > To determine _when_ this state should be enabled and disabled would
>> > be a 
>> > different story.
>> 
>> For the moment let's assume I know it ;‑) ping‑node, maybe.
> 
> I believe that limited scenario is possible, but imperfectly.
> 
> You could configure an ocf:pacemaker:ping resource to ping the NFS
> server IP. Then in the dependent resource, configure the recurring
> monitor logically like this:
> 
>   monitor interval=N
>      meta attributes
>         rule when ping attribute lt 1 or not defined
>         enabled=false

Assuming my attribute is named "n_up", would the syntax be (sorry, I'm not
fluent with rules):
"rule when n_up lt1 or not defined"

>From your example it's not quite clear which words are placeholders and which
are reserved words...

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