Alerts - HOSTS matching regular expressions.

Kii NODA kii.noda at gmail.com
Thu Jan 28 21:45:26 CET 2010


Hi everyone,

As you may have already been aware by now, we're here to stay. :)

Here's one interesting problem (and maybe simple) for you: We've seen that
"HOST=%^asd$" matches both hosts named "asd" and "asdf", not respecting the
"$" at the end. Can you guys please confirm that regex matching for "HOST="
does not care about the "$" sign?

For those that need some expanded case-study (all others can now stop),
here's the story behind: we are managing various servers of ours and our
customers. Due to the fact that we do not control DNS entries for all these
machines we have come up with a naming scheme like this:

--- cut here ---
junkyard-starbox # clientID=junkyard, starbox=actual machine
junkyard-starbox-v_trash # v_trash=vserver named trash running on starbox
junkyard-starbox-v_trashcan # v_trashcan=vserver named trashcan running on
starbox
junkyard-starbox-x_dustbin # x_dustbin=xen server running on starbox
--- and here ---

We need to send these "special" alerts:
* ONLY cto at junkyard.tld for events on junkyard-starbox-v_trash
* ONLY ceo at junkyard.tld for events on junkyard-starbox-x_dustbin

Also, we need to send these alerts for all other hosts & events:
* stars at sysadmins.tld for purple, yellow & red w/ REPEAT=60
* cto at sysadmins.tld for red w/ DURATION>30 and REPEAT=60
* cto at sysadmins.tld for yellow&purple w/ DURATION>60 and REPEAT=60

Exercising our brain muscles we came up with these:
--- cut here ---
#alert CTO for v_trash
HOST=junkyard-starbox-v_trash
  MAIL=cto at junkyard.tld

#alert CEO for x_dustbin
HOST=junkyard-starbox-x_dustbin
  MAIL=ceo at junkyard.tld

#stop alerting for the private boxes above
HOST=*
  IGNORE HOST=%^junkyard-starbox-(v_trash|x_dustbin)$

HOST=* COLOR=purple,yellow
  MAIL=stars at sysadmins.tld REPEAT=60 RECOVERED NOTICE
  MAIL=cto at sysadmins.tld DURATION>60 REPEAT=60 RECOVERED NOTICE

HOST=* COLOR=red
  MAIL=stars at sysadmins.tld REPEAT=10 RECOVERED NOTICE
  MAIL=cto at sysadmins.tld DURATION>30 REPEAT=60 RECOVERED NOTICE
--- and here ---

However, even with the "$" at the end of our regex we are no longer
receiving any alerts for v_trashcan because the regex wrongly matches on the
"IGNORE HOST=" line. We could use 2 lines to match each host on its own line
but that's not the point of this exercise.

So, can anyone confirm our finding?
-- 
kN
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