After some pleas in other similar threads, and some prodding in the right
direction by kgoedtel and jamesroman, I finally have thresholds working for my
custom OIDs. I'm still not sure why some of it works, but I figured I'd just
post my findings for anyone who is trying to do the same thing, and if anyone
can point out a refined solution, it will be welcomed.
It turns out my problem is the output of a script driven by exec (in
snmpd.conf) will always be a String. If Zenoss collects data as a string, you
can't compare the data to a number (like a threshold does). The answer is to
set your script's output to a Gauge (or whatever type is appropriate). kgoedtel
pointed me towards using pass.
pass is another way to extend snmpd.conf and is similar to exec. However,
instead of executing a script directly, you tell snmp that when a specific OID
is requested, to pass the request to a script and the script can define what
the output looks like.
kgoedtel was kind enough to give me a script of his, but unfortunately, I'm not
comfortable enough with Perl to tweak it. However, while rereading the
snmpd.conf man pages, I noticed a script called passtest was mentioned. After
some searching, I found a copy of it:
passtest
Code:
#!/bin/sh -f
PATH=$PATH:/bin:/usr/bin:/usr/ucb
PLACE=".1.3.6.1.4.1.2021.255"
REQ="$2"
if [ "$1" = "-s" ]; then
echo $* >> /tmp/passtest.log
exit 0
fi
if [ "$1" = "-n" ]; then
case "$REQ" in
$PLACE) RET=$PLACE.1 ;;
$PLACE.1) RET=$PLACE.2.1 ;;
$PLACE.2.1) RET=$PLACE.2.2 ;;
$PLACE.2.2) RET=$PLACE.3 ;;
$PLACE.3) RET=$PLACE.4 ;;
$PLACE.4) RET=$PLACE.5 ;;
$PLACE.5) RET=$PLACE.6 ;;
*) exit 0 ;;
esac
else
case "$REQ" in
$PLACE) exit 0 ;;
*) RET=$REQ ;;
esac
fi
echo "$RET"
case "$RET" in
$PLACE.1) echo "string"; echo "life the universe and everything"; exit 0 ;;
$PLACE.2.1) echo "integer"; echo "42"; exit 0 ;;
$PLACE.2.2) echo "objectid"; echo ".1.3.6.1.4.42.42.42"; exit 0 ;;
$PLACE.3) echo "timeticks"; echo "363136200"; exit 0 ;;
$PLACE.4) echo "ipaddress"; echo "127.0.0.1" ;;
$PLACE.5) echo "counter"; echo "42"; exit 0 ;;
$PLACE.6) echo "gauge"; echo "42"; exit 0 ;;
*) echo "string"; echo "ack... $RET $REQ"; exit 0 ;;
esac
I figured my best first step was to get the example working, and then modify
it. I used the same settings outlined in the man pages:
snmpd.conf
Code:
pass .1.3.6.1.4.1.2021.255 /usr/local/bin/passtest
So running:
Code:
snmpwalk -c public -v2c zenoss .1.3.6.1.4.1.2021.255
gave me the expected output:
Code:
UCD-SNMP-MIB::ucdavis.255.1 = STRING: "life the universe and everything"
UCD-SNMP-MIB::ucdavis.255.2.1 = INTEGER: 42
UCD-SNMP-MIB::ucdavis.255.2.2 = OID: SNMPv2-SMI::private.42.42.42
UCD-SNMP-MIB::ucdavis.255.3 = Timeticks: (363136200) 42 days, 0:42:42.00
UCD-SNMP-MIB::ucdavis.255.4 = IpAddress: 127.0.0.1
UCD-SNMP-MIB::ucdavis.255.5 = Counter32: 42
Looking at passtest I see that is has the base OID hardcoded and stored in
PLACE. Then, depending on the request type (-n -g or -s), it compares the base
OID to the requested OID and figures out which value to send. So if you ran:
Code:
snmpget -c public -v2c zenoss .1.3.6.1.4.1.2021.255.1
passtest would see you requested an OID equal to $PLACE.1 and would output
"life the universe and everything". Notice passtest needs to return 3 lines:
the OID, the type for the value, and the value.
So my next thought was I could just remove the entries from the case condition
at the bottom of passtest and write one for each of the scripts I want to use
with Zenoss. I tried this, but ended up getting the message:
>
> UCD-SNMP-MIB::ucdavis.255.1 = No Such Instance currently exists at this OID
>
I backed out my changes and tried adding new conditions to the case. So to
check our room temp, and return the value as a gauge, I added this line:
Code:
$PLACE.7) echo "gauge"; /usr/local/bin/readtemp -d /dev/ttyUSB0 -1 -q; exit 0
;;
I also added this line to the first case block in passtest:
Code:
$PLACE.6) RET=$PLACE.7 ;;
And it worked! I added my other scripts, changed the OID in the data sources in
Zenoss, and my custom thresholds started working as expected! I'm not sure why
replacing all of the cases with my custom scripts didn't work, but perhaps I
made a mistake, or I'm making an assumption that isn't true. I know that I can
replace the existing gauge ($PLACE.6) with my own and I'll keep playing with it
and report my findings here.
Anyway, I hope this can be of help to someone who is trying the same thing I am!
Nate
-------------------- m2f --------------------
Read this topic online here:
http://community.zenoss.com/forums/viewtopic.php?p=12744#12744
-------------------- m2f --------------------
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