Re: monit '-i' option?

[Martin Pala]

Jan-Henrik Haukeland wrote:

> Jan-Henrik Haukeland <address@hidden> writes:
>  
>
> Are there other solutions, preferably simple? I know to little about
> init, but can something be done there? I'm not thinking about e.g to
> start monit in the last run level and stuff like that because that is
> just a poorer variant of using the -i switch in monit.
>
>  
The other solution could be, to modify startup rc scripts of critical 
services to block until the service will be realy up or timeout will 
occure. This can solve the problem too, because init wait for rc script 
(which starts particular runlevel scripts) to terminate:

id:2:initdefault:
...
l2:2:wait:/etc/init.d/rc 2
...
mo:2345:respawn:/usr/local/bin/monit -Ic /etc/monitrc

As you can see, init waits until rc will finish its work and then starts 
other services (such as monit). If you add monit behind rc in inittab 
and modify critical services's rc scripts to not return until they are 
realy running or broken, you can reach the requested behavior too + the 
race condition will not occure. The only problem with this solution is 
the *broken* case - monit will detect that the service is not running on 
its own (which will not occure in the case that the services are started 
from monit directly as explained earlier). This solution requires also 
modification of all rc scripts for "slow" critical services.

Conslusion: this is another option, where no race condition will occure 
- on the other hand it is less comfortable and practical then '-i' 
option and then starting services from monit directly as well (more 
work) - in addition it is less secure in the broken case.

In the case that the services are realy critical (such as database, 
which could be in recovery stage that can take very long time), it is 
better and more secure for it to use monit to start it unless you are 
monitoring this service in passive mode. This can prevent recovery 
interruption.

I think in the case that -i option will be re-added, we should mention 
the problem and recommend to start services from monit. If these 
services are not critical, '-i' option could be practical choice.

I'll keep my votes (+0 for extended '-i' and -1 for original 
implementation).

Martin