[ClusterLabs] Order constraint with a timeout?

[Ken Gaillot]

On Mon, 2022-03-28 at 17:26 -0400, john tillman wrote:
> > On Mon, 2022-03-28 at 14:03 -0400, john tillman wrote:
> > > Greetings all,
> > > 
> > > Is it possible to have an order constraint with a timeout?  I
> > > can't
> > > find
> > > one but perhaps I am using the wrong keywords in google.
> > > 
> > > I have several Filesystem resource and one nfs service
> > > resource.  If
> > > I
> > > create 3 order constraints:
> > >    pcs constraint order start fsRsc1 then start myNfsServiceRsc
> > >    pcs constraint order start fsRsc2 then start myNfsServiceRsc
> > >    pcs constraint order start fsRsc3 then start myNfsServiceRsc
> > > 
> > > I would like to make sure that the nfs service will be started
> > > even
> > > if one
> > > of the Filesystem resources fails to start.  Is there a timeout
> > > that
> > > could
> > > be used?
> > > 
> > > There is the "kind=Optional" parameter but that looks like it
> > > will
> > > immediately start the second resource if the first failed to
> > > start.  There
> > > is no timeout option.
> > > 
> > > Best regards,
> > > -John
> > > 
> > 
> > How do you envision the timeout working?
> > 
> > You can add a timeout for the ordering itself using rules, where
> > the
> > ordering no longer applies after a certain date/time, but it
> > doesn't
> > sound like that's what you want.
> > --
> > Ken Gaillot <kgaillot at redhat.com>
> > 
> 
> Thank you for the reply, Ken.
> 
> I was hoping that I could give the Filesystem resource "X" seconds to
> start.  If it failed to start after "X" then I would start the nfs
> service
> anyway.  So Those Filesystems that successfully started could be
> accessed,
> albeit with a bit of a delay before nfs is started.
> 
> Basically, I want to start the nfs service regardless of whether any
> or
> all of the Filesystem resources started.  But I want to give them all
> a
> chance start before starting nfs.
> 
> That said, it doesn't look like the rules suggestion you made is what
> I
> need.  Any other ideas?
> 
> Best Regards,
> -John
> 

I don't think there is a way to do that except maybe with customizing
the filesystem resource agent.

If you customized the agent, you could have it set a transient node
attribute (like fs-<RESOURCE ID>) when attempting to start, regardless
of whether it succeeded or failed. Then you could configure a location
constraint for the nfs server using a rule that allows the nfs server
to run only on a node where all three node attributes have been
defined.
-- 
Ken Gaillot <kgaillot at redhat.com>