Re: monit watchdog timer restart

[Martin Pala]

I'm sorry, my suggestion was not correct.

Monit propagates the events upwards (which is logical :) For example if 
you have following chain:

A->B->C

where A depends on B depends on C, and C will fail, all depending 
services (A and B) will inherite the same event (stop for example). 
However if A only related event occures, it is not inherited to its 
parents - they can work independent of A state.

So in your case probably the following setup could work (corrected):

 check process AppManager with pidfile "/var/lxs/run/AppManager.pid"
  start program = "/opt/lxs/bin/lxs.sh start AppManager"
  stop program = "/opt/lxs/bin/lxs.sh stop AppManager"

 check file AppManager_monit with path "/var/lxs/run/AppManager.monit"
  if timestamp > 2 minutes then exec "/usr/bin/monit stop AppManager"
  depends on AppManager


=> in the case that the process AppManager failed (and doesn't update 
its state file anymore), you will stop it via monit's interface. This 
way monit will be instructed to cleanly stop the service including its 
dependant AppManager_monit (file monitoring). If you will call service 
init script directly, monit will think that the service failed and will 
start it again - thus following setup is wrong:

  ...
  if timestamp > 2 minutes then exec "/opt/lxs/bin/lxs.sh stop
  ...

The princip is common in cluster frameworks generaly (for example Sun 
Cluster) - if the service is under cluster control, you must use 
cluster's resource management instead of direct "shot" (for such case 
you need to bring the service out of cluster control).

Martin


Peter Holdaway wrote:
> I have tried this and the stop action does not affect the process.
>
> monit.log says...
>
> [ Feb 24 14:32:18] start: (AppManager) /opt/lxs/bin/lxs.sh
> [ Feb 24 14:34:37] Event: timestamp test failed for
> /var/lxs/run/AppManager.monit
>
>
> monit status says...
>
> Process 'AppManager'                running
> File 'AppManager_monit'             not monitored
>
>
> Is this a bug?
>
> Regards,
>
>   Peter
>
>
> > -----Original Message-----
> > From: address@hidden
> > [mailto:address@hidden
> > On Behalf Of Martin Pala
> > Sent: Tuesday, 24 February 2004 2:12 PM
> > To: This is the general mailing list for monit
> > Subject: Re: monit watchdog timer restart
> >
> > Hi, following setup should work in this case:
> >
> >  check process AppManager with pidfile "/var/lxs/run/AppManager.pid"
> >   start program = "/opt/lxs/bin/lxs.sh start AppManager"
> >   stop program = "/opt/lxs/bin/lxs.sh stop AppManager"
> >
> >  check file AppManager_monit with path "/var/lxs/run/AppManager.monit"
> >   if timestamp > 2 minutes then stop
> >   depends on AppManager
> >
> >
> > Stop events are inherited via dependency, though the depending file-type
> > service has no stop method defined.
> >
> >
> > Martin
> >
> > Peter Holdaway wrote:
> >
> > > Hi,
> > >
> > >  I would like some advice on the simplest way to implement a watchdog
> >
> > timer
> >
> > > restart of a process. Perhaps this could also be added to the
> >
> > documentation
> >
> > > too.
> > >
> > >  I have a process that should be regularly updating a file. If it is
> >
> > not I
> >
> > > can assume the process is broken and should be restarted. In the absence
> >
> > of
> >
> > > a network protocol, this is often the easiest way to instrument a
> >
> > process
> >
> > > for monitoring its readiness to perform work.
> > >
> > >
> > >  In version 3.2 of monit this was accomplished by...
> > >
> > > check AppManager with pidfile /var/lxs/run/AppManager.pid
> > >    start program = "/opt/lxs/bin/lxs.sh start AppManager"
> > >    stop program = "/opt/lxs/bin/lxs.sh stop AppManager"
> > >    if timestamp "/var/lxs/run/AppManager.monit" > 2 minute then restart
> > >
> > >
> > >  Is the following the best expression of this problem in monit 4.2 ?
> > >
> > >
> > > check process AppManager with pidfile "/var/lxs/run/AppManager.pid"
> > >    start program = "/opt/lxs/bin/lxs.sh start AppManager"
> > >    stop program = "/opt/lxs/bin/lxs.sh stop AppManager"
> > >
> > > check file AppManager_monit with path "/var/lxs/run/AppManager.monit"
> > >    if timestamp > 2 minutes then exec "/opt/lxs/bin/lxs.sh stop
> >
> > AppManager"
> >
> > >    depends on AppManager
> > >
> > >
> > > Notice the unusual direction of the dependency. There do not seem to be
> >
> > any
> >
> > > examples of this in the documentation.
> > >
> > > This dependency is required so that when "monit stop AppManager" is
> >
> > issued
> >
> > > then the AppManager_monit service is also stopped.
> > >
> > > This solution requires two time periods to restart the process, one for
> >
> > the
> >
> > > timestamp and one for the process restart.
> > >
> > >
> > > TIA
> > >
> > >  Peter