Re: it scares me a bit...

[Vlada Macek]

alex black wrote:

> It's all very well and good if apache is running - but if something
> else has screwed up (either in code recently promoted,
> configuration, etc) then it's useless. The only way I can be
> satisfied that it is running correctly is to have some ability to
> test URLs - if those tests fail it's great to get a message from
> monit saying something like... I tried to restart apache to solve
> this problem but that didn't work - time for you to do something.

Most of this is already present in monit. In addition monit may check
the HTTP return code, it would be cheap. But once it is able to
checksum the HTTP content, it actually checks more than just the
return code (200 OK) and such extension would be IMO useless. You may
have some blind file with known checksum on the webserver, which you
could exclude from your web logs (as was previously adviced on the
list). By this you'll check static page serving.

>From what you are saying I'm not convinced even you really need the
"Remote page grepping" feature you originally proposed. Even armed
with this feature, you will not be able to check that your dynamic
content is served properly. For these purposes I propose you to create
some clever self-diagnostics script on the remote web server, which
e.g. checks the database backend, does some queries etc., and if all
is okay, returns the content with a known checksum. This output may
again be checked by monit's existing facility.

By self-diagnostics web script you will be able to do checks that will
by far exceed monit's abilities (with grepping included!), just
because it will be written by you and only you exactly know what to
check. As a cherry on a cream, you can make a script output human
readable status page. Once it's checksum changes, monit alerts and
anyone can peek with a browser and see what is wrong in detail. Monit
tells you only "Bad, but I'm trying, man...".

As I said, I do not see the purpose for such expensive feature as is
fixed string grepping.

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