On Tue, Jan 31, 2012 at 11:34:19AM +0100, Lars Ellenberg wrote:
> On Mon, Jan 30, 2012 at 09:24:19PM +0100, Dejan Muhamedagic wrote:
> > > As for the regular expression like ^ or $, it looks like working as
> > > expected with -z option in my quick tests.
> > > Do you have any examples that it may break the configuration?
> > 
> > For instance, what I see here in the status page is also a PID at
> > the beginning of line:
> > 
> > xen-d:~ # wget -q -O- -L --no-proxy  --bind-address ::1 
> > http://[::1]/server-status | grep ^PID
> > PID Key: <br />
> > xen-d:~ # wget -q -O- -L --no-proxy  --bind-address ::1 
> > http://[::1]/server-status | grep -z ^PID
> > xen-d:~ # echo $?
> > 1
> 
> different versions of grep in various distributions seem to behave
> differently with -z and ^:
> 
> distro;
> grep --version | head -n1;
> printf "A\nB\nC\n" | grep -q -z ^B ; echo $?
> 
> etch        grep (GNU grep) 2.5.1   0
> lenny       GNU grep 2.5.3          0
> squeeze     GNU grep 2.6.3          1   breaks
> lucid       GNU grep 2.5.4          0
> 
> rhel4       grep (GNU grep) 2.5.1   1   breaks
> rhel5       grep (GNU grep) 2.5.1   0
> rhel6       GNU grep 2.6.3          1   breaks
> 
> sles9       grep (GNU grep) 2.5.1   1   breaks
> sles10      grep (GNU grep) 2.5.1   1   breaks
> sles11      GNU grep 2.5.2          1   breaks
> sles11-sp1  GNU grep 2.5.2          1   breaks

sles11-sp2  GNU grep 2.7          1   breaks

Lovely. SLES is at least consequent.

> So neither distros nor grep version seem to agree
> if "^" is supposed to be equivalent to pcre /^/m or /\A/ ;-)
> 
> Best practices for monitoring apache with pacemaker
> would be to have some dedicated page print out
> either a text/plain "ALL OK" only.
> Or, in case something is wrong, anything with arbitrary diagnostic
> output, if any, which reliably does not containing that string.

Right. Searching for just <html> could conceivably at times
match a wrong output.

> > But we could just as well reduce to the default regular
> > expression to '</ *html *>'. If nobody objects :)
> 
> As the default regex only checks for basically "any" response that
> remotely looks like it may have something to do with html output,
> that should be fine.

Yes, I think so to.

Cheers,

Dejan

> -- 
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
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