Re: String/regex based healthcheck.

From: Brandorr <>
Date: Mon, 5 May 2008 18:24:32 -0400

On Mon, May 5, 2008 at 5:33 PM, Willy Tarreau <> wrote:
> [cc'd Brian in case he's not subscribed]
> On Tue, Apr 29, 2008 at 11:40:24PM +0200, Aleksandar Lazic wrote:
> > Hi Brian,
> >
> > On Die 29.04.2008 17:36, Brandorr wrote:
> >
> > >Is there a way to check a specific "status page", for specific HTML.
> > >(I see I can set the URI for httpchk). I ask because sometimes an app
> > >can return proper HTML without an error code, but still be broken.
> > >(Our developers setup a dynamic webpage for monitoring the application
> > >stack that simply returns a web page that contains the string "OK")
> >
> > For know haproxy don't take a look in the content of the response.
> >
> > Is it possible to return a proper HTTP-Code instead the OK in the body?
> I confirm it is not possible. One customer has already asked for this
> feature to detect anomalies in web pages. He wanted to be able to both
> consider a server down if one particular regex was found, as well as
> if a particular regex was not found.
> I explained that while it would not be too hard to implement, we have
> to know exactly what and who we want to test. First, having a regex
> which applies only to the first part of the page which fits the read
> buffer would make sense (8 or 16 kB max), but bringing the ability
> to parse all of it whatever its size is another story.
> Second, we have to think about combinations. I have nothing against
> complex checks, but we should not change them every other day, so we
> need either something very simple, or something extensible.
> But for now, no regex and no condition :-/
> An alternative to complex tests is often to dedicate a port on the
> server, and put a ridiculously trivial shell script which does all
> the work through inetd. Haproxy then monitors this port instead of
> the default one. It allows one to apply grep, awk, perl, whatever
> you need on the response and finally return 200/404/500.

I talked to the devs, and we are ok with the current health check method. (HTML response codes).

> Cheers,
> Willy

- Brian Gupta
Received on 2008/05/06 00:24

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