Re: Feature request for config file checking?

[Rick Robino]

On Tuesday, June 10, 2003, at 11:11  PM, Mark Ferlatte wrote:

> I want to be able to run any script.  Simply a:
>
> check timestamp foo.conf if changed then run "/etc/init.d/foo restart"
>
> solves all of these problems easily.
>
> > "timestamp" remains flexible so that we can AND an alert, execute
> > restart script or whatever besides/rather-than just sending a signal?
>
> Just run a script that sends kill -SIG.  No need for monit to have to 
> add more
> special case parsing.

That is what I meant to imply when I said:

> On a related note, w.r.t to the discussion about keyword alternatives: 
>  maybe a line like the above suggests a `cmd` or $(cmd) shell-style 
> command substitution expression as a way to handle arbitrary solutions 
> where a keyword doesn't yet exist?

So - I also agree with this idea:  + for the ability to run arbitrary 
commands (whatever the syntax).  The command could be fed the subject 
of the expression - pid, timestamp, timeout, etc, as first and only 
argument.  At least the pid.

If some primitive conditional expression becomes part of monit's 
vocabulary as proposed in J-H's RFD it may also be worth discussing the 
notion of checking the return code of the proposed arbitrary command, 
so as to branch to other statements if the first command did not exit 
0.  For one, it may alleviate the temptation to make a single command 
allowed cover all cases by itself outside of monit, possibly to the 
point of duplicating some of monit's own functionality.  For two, it 
would satisfy generically many more complicated needs than executing 
one command that may only fail timeout*times and eventually leave the 
service down.

Of course this may constitute serious featurecreep, and checking the 
return value requires monit to wait for the command to terminate 
(potential for problems), but it is a natural complement to the ability 
to run scripts other than start/stop and in light of other proposed 
syntax changes.

Being able to run a command besides start or stop on a per-check basis 
like timestamp is a big win already, maybe there is no reason for 
further conditional processing - and it could be that I have even 
misunderstood the "if" proposal on the table in thinking that checks 
can have individual responses.  Maybe if timeouts could be expressed in 
a way where monit would execute the arbitrary command if timeout n is 
reached the same problem would be solved without as much fuzz.

I don't know, but if the movement is towards more complex functionality 
then this sort of granular control is something I would like to see.  
Just a thought.  Apologies for extending the scope of this subject to 
that of the general control file language.

--
Richard T. Robino