SNMP plugin doesn't write proper instance value

[slemire]

I'm having issues polling the virtual server stats off an F5 load-balancer. It seems like the snmp plugin doesn't write the proper value in the instance field. In the example below, it's not writing two levels of OIDs below what I've defined in the configuration. That throws off the mapping table when I try to use it. In the example I'm not using the mapping table but you can see the data written in InfluxDB is missing two OID levels above .47.

[[inputs.snmp.table]]
        name = "ltmVirtualServStatEntry"
        oid = ".1.3.6.1.4.1.3375.2.2.10.2.3.1"

Database measurements:

> select * from ltmVirtualServStatClientBytesIn where time > now() - 1m
name: ltmVirtualServStatClientBytesIn
-------------------------------------
time                    dc      host            instance                                                        ltmVirtualServStatClientBytesIn
1460818130000000000     Home    172.23.10.30    47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49      0
1460818130000000000     Home    172.23.10.30    47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51      0
1460818130000000000     Home    172.23.10.30    47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50      0
1460818140000000000     Home    172.23.10.30    47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51      0

Here's the snmpwalk of the OID:

slemire@dev:~/telegraf$ snmpwalk -v 2c -c <secret> 172.23.10.30 .1.3.6.1.4.1.3375.2.2.10.2.3.1
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.1.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49 = STRING: "/Common/test_vs1"
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.1.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50 = STRING: "/Common/test_vs2"
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.1.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51 = STRING: "/Common/test_vs3"
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.2.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.2.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.2.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.3.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.3.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.3.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.4.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.4.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.4.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.5.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.49 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.5.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.50 = Counter64: 0
SNMPv2-SMI::enterprises.3375.2.2.10.2.3.1.5.16.47.67.111.109.109.111.110.47.116.101.115.116.95.118.115.51 = Counter64: 0
[...]

[slemire]

Added pcap file
snmptable1.pcap.zip

[sparrc]

Maybe I'm not quite reading this right, what are the 2 OID levels that are missing?

[slemire]

.1.16 is missing

[sparrc]

got it, I see what you mean, @titilambert do you happen to know why those two elements of the instance wouldn't be included?

[titilambert]

hum, I did never hit this bug :(
@slemire The best thing to do, if you can do it, is to make a snmp dump using snmpsim: http://snmpsim.sourceforge.net/
Can you do that ?
With the dump I will be able to reproduced it

[titilambert]

This could be fix with #1044
@slemire could you try to compile Telegraf with this patch ? and test it ?

[slemire]

Sure thing, I captured the following:

snmprec.py --agent-udpv4-endpoint=172.23.10.30 --protocol-version=2c --start-oid=.1.3.6.1.4.1.3375.2.2.10.2.3.1 --stop-oid=.1.3.6.1.4.1.3375.2.2.10.2.3.1.44 --output-file=test.snmprec

test.snmprec.txt

[titilambert]

@slemire thanks ! Could you give me your telegraf configuration ?

[slemire]

Here's the config:

telegraf.txt

[slemire]

Problem is still there using the latest nightly:
Telegraf - Version 0.13.0~n1461140359

[slemire]

I think maxRepetition := uint8(32) might have something to do with it.

My OID tree is longer than that.

[sparrc]

I see, I think that has come up before, we may want to make that a configurable option. What do you think @titilambert?

[slemire]

Um, I think I got confused. The maxRepetition is just the standard SNMP RFC knob to manage the size of SNMP bulk GETs. I've tried smaller and larger settings without success.