munin eth0 traffic graphs missing, patch

[glaszig]

i'm running on a ubuntu 14.04 droplet on digitalocean.

munin did show missing graphs for eth0 traffic. a quick lock into /var/log/munin/munin-update.log revealed some issue with how the rrd configuration was being created.

2016/08/02 23:30:02 [INFO]: Starting munin-update
2016/08/02 23:30:02 [INFO] starting work in 31337 for mx.example.com/127.0.0.1:4949.
2016/08/02 23:30:07 [INFO] creating rrd-file for if_eth0->down: '/var/lib/munin/example.com/mx.example.com-if_eth0-down-d.rrd'
2016/08/02 23:30:07 [ERROR] Unable to create '/var/lib/munin/example.com/mx.example.com-if_eth0-down-d.rrd': min must be less than max in DS definition
2016/08/02 23:30:07 [ERROR] In RRD: Error updating /var/lib/munin/example.com/mx.example.com-if_eth0-down-d.rrd: opening '/var/lib/munin/example.com/mx.example.com-if_eth0-down-d.rrd': No such file or directory
2016/08/02 23:30:07 [INFO] creating rrd-file for if_eth0->up: '/var/lib/munin/example.com/mx.example.com-if_eth0-up-d.rrd'
2016/08/02 23:30:07 [ERROR] Unable to create '/var/lib/munin/example.com/mx.example.com-if_eth0-up-d.rrd': min must be less than max in DS definition
2016/08/02 23:30:07 [ERROR] In RRD: Error updating /var/lib/munin/example.com/mx.example.com-if_eth0-up-d.rrd: opening '/var/lib/munin/example.com/mx.example.com-if_eth0-up-d.rrd': No such file or directory
2016/08/02 23:30:07 [INFO]: Munin-update finished for node example.com;mx.example.com (5.01 sec)

i then ran the if_eth0 plugin manually which yielded a negative value for the DS MAX value of the rrd config - see down.max -1000000 and up.max -1000000

# /etc/munin/plugins/if_eth0 config
graph_order down up
graph_title eth0 traffic
graph_args --base 1000
graph_vlabel bits in (-) / out (+) per ${graph_period}
graph_category network
graph_info This graph shows the traffic of the eth0 network interface. Please note that the traffic is shown in bits per second, not bytes. IMPORTANT: On 32-bit systems the data source for this plugin uses 32-bit counters, which makes the plugin unreliable and unsuitable for most 100-Mb/s (or faster) interfaces, where traffic is expected to exceed 50 Mb/s over a 5 minute period.  This means that this plugin is unsuitable for most 32-bit production environments. To avoid this problem, use the ip_ plugin instead.  There should be no problems on 64-bit systems running 64-bit kernels.
down.label received
down.type DERIVE
down.graph no
down.cdef down,8,*
down.min 0
up.label bps
up.type DERIVE
up.negative down
up.cdef up,8,*
up.min 0
up.max -1000000
up.info Traffic of the eth0 interface. Maximum speed is -1 Mb/s.
down.max -1000000

then i went to munin on github and looked at the plugin's history just to find 2 commits around this issue:

• munin-monitoring/munin@78c3c3aa
• munin-monitoring/munin@f982751a

applying munin-monitoring/munin@f982751a manually to the plugin on my machine resolved the issue. the following is the diff which might be helpful to others and maybe should be integrated with mailinabox by way of just applying the patch or maintaining a seperate ppa or somehow pulling in a version of munin newer than 2.0.19 (which was released in 2014).

--- if_.orig    2016-08-02 23:52:05.691224811 +0200
+++ if_ 2016-08-02 23:52:49.563223127 +0200
@@ -91,7 +91,7 @@
     # iwlist first)
     if [[ -r /sys/class/net/$INTERFACE/speed ]]; then
             SPEED=$(cat /sys/class/net/$INTERFACE/speed 2>/dev/null)
-            if [[ -n "$SPEED" ]]; then
+            if [ -n "$SPEED" -a "$SPEED" -gt "0" ]; then
                 echo $SPEED
                 return
             fi

if you trust the internet, you can apply this patch with this one-liner:

curl -Ls https://gist.github.com/glaszig/02cb28c47453906fb64b918c2c9d5189/raw/c92bc1b419a7649f82009f7081836e47442c83c0/if_.patch | patch -b /usr/share/munin/plugins/if_

(be root before doing so)

[monotek]

Same problem on Ubuntu 16.04 Patch worked.

[lexo13]

Same problem on Ubuntu 16.04 for me. Patch worked.

[dmuth]

I am sad to say that applying this patch did NOT work for me on a fresh Ubuntu 16.04 instance on Digital Ocean. I ended up putting:

SPEED=1000

on line 130 of /usr/share/munin/plugins/if_.

I don't know the Munin project (or its source) all that well--if anyone here has suggestions for how a change could be made to force Munin to treat Ethernet devices at 1 Gigabit to prevent this sort of breakage, I'm all for it--and I'll even help write the patch.

-- Doug

[ghost]

The patch fixed the issue on my Ubuntu 16.04 nodes.

[JunkTapes]

Big thanks for the patch! Worked on my 14.04 and 16.04 Ubuntu nodes

[foto-andreas]

Thank you for the patch! Ubuntu 16.04.

[wouterbudding]

Also this patch did not help me directly, but pointed me in a good way. I added (after the patch) on line 97 the following:

            else
                echo "1000"
            return

and now finally one of my graphs is created! I think the reason the patch didn't work at first time is that the result of cat /sys/class/net/ens3/speed is " -1 " :(. Running a VPS with Leaseweb NL.

[pimlie]

This is a common problem for virtual network devices. In these cases you can also manually set the interface speed with ethtool (if your distro is recent enough), e.g.

ethtool -s eth0 speed 1000 duplex full

See these links: https://serverfault.com/questions/738840/get-link-speed-of-an-virtio-net-network-adapter https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1581132