Re: [monit] How to Achieve "if x restarts within y cycles then exec ..."

[Martin Pala]

Art Age Software wrote:
> On Thu, Jun 26, 2008 at 4:27 PM, Martin Pala <address@hidden> wrote:
> > Art Age Software wrote:
> > > I would like to be able to execute an arbitrary action after a
> > > specified number of restart attempts have failed. It appears that the
> > > only thing allowed in the "if x restarts within y cycles" clause is
> > > the timeout command. Is that true?
> > Yes, that's true. We plan to add this feature, there is also patch from Alec
> > which implements it. I'll look on it and will try to integrate with upcoming
> > monit 5.0.
>
> Thanks. Is there any work-around in the meantime? I was thinking of
> creating a second "ghost" service that attempts to connect to mysql
> each cycle and forces a failover if it cannot connect (but before the
> other service times out). Something like:
>
> ---------------------
> check process mysql1 with pidfile /var/run/mysqld/mysqld.pid
>   mode manual
>   every 2 cycles
>   if failed unix "/var/lib/mysql/mysql.sock" then restart
>   if failed host localhost port 3306 protocol mysql then restart
>   if 5 restarts within 10 cycles then timeout
>
> check host mysql2 with address localhost
>   mode manual
>   if failed port 3306 protocol mysql for 6 cycles then exec
> "/usr/lib/heartbeat/hb_standby"
> ---------------------
>
> What do you think? Or is there a better approach?

Yes, this could work. Optionally it could be possible to use the pidfile 
using similar approach:

--8<--
check process mysql with pidfile /var/run/mysqld/mysqld.pid
   mode manual
   every 2 cycles
   if failed unix "/var/lib/mysql/mysql.sock" then restart
   if failed host localhost port 3306 protocol mysql then restart
   if 5 restarts within 10 cycles then timeout

check file mysql_pidfile with path /var/run/mysqld/mysqld.pid
   mode manual
   if changed timestamp for 5 cycles then exec 
"/usr/lib/heartbeat/hb_standby"
--8<--

On restart the script will change the timestamp of the pidfile => the 
second service check can trigger failover/standby based on it.

Martin