Tag: munin

I got a mail in my inbox about a week ago from Anthony, telling me how to improve my Munin & temp script for a RPi:

Hi,

I just read your (old) blog post about monitoring the temperature of the Raspberry Pi with munin[1].

I had the exact same error as you did when I was trying to let munin do the job all by himself:

> temp.value VCHI initialization failed)

It turns out the solution was quite easy: in

/etc/munin/plugin-conf.d/munin-node

You simply need to tell munin that it needs to run as root for this specific plugin:

> [pisense_]

> user root

(the plugins also tracks clock speeds and voltages but any other will work just fine as long as the “user root” is set in the munin-node plugin config file : [2]). Probably the easiest way to check if it’s working is to use munin-run command before and after the change.

“Demo”: [3]

By the way, “Connect different LANs over openVPN” is pretty tempting, I always wondered what the performances would be like through a USB-to-ethernet adapter.

Have a nice one !

Apteno

[1] https://yeri.be/munin-raspberry-pi-temperature
[2] https://github.com/perception101/pisense/blob/master/pisense_
[3] http://ronon.jefter.com/jefter.com/adama.jefter.com/index.html#sensors

And indeed, I knew it was a permission issue, but instead of running this script as root, I tried adding Munin to a group that was supposed to be able to run  vcgencmd (which didn’t work out).

But, let’s look at a simpler solution:

1. Go to /etc/munin/plugins and create a file temp with this content (and some indentation yourself):

   #!/bin/sh
   case $1 in
   config)
   cat <<'EOM'
   graph_category system
   graph_title Temperature
   graph_vlabel temp
   temp.label Celsius
   EOM
   exit 0;;
   esac
   echo -n "temp.value "
   /opt/vc/bin/vcgencmd measure_temp | cut -d "=" -f2 | cut -d "'" -f1

2. As you noticed, this doesn’t require any more scripts to run from cron (and thus, in case you used my previous script, remove it from cron)

3. chmod +x temp

4. Make sure it runs as root; in /etc/munin/plugin-conf.d create the file temp.conf with this content:

   [temp]
   user root

5. Test it:

   # munin-run temp
   temp.value 59.5

Tadaaaa. Simpler.

Thanks Anthony 🙂

Quick hack to get Munin to graph the cpu temperature.

First of all, install Munin and make sure it’s working.

Then follow these steps:

1) We’ll use cron to write the current temp to a log file. We do this because I wasn’t able to get Munin to directly execute the command (error: temp.value VCHI initialization failed)

Execute crontab -e and add this line (this has to be on one line):

*/5 * * * * /opt/vc/bin/vcgencmd measure_temp | cut -d "=" -f2 | cut -d "'" -f1 > /tmp/.temp

2) Go to /etc/munin/plugins/, and create a file temp, and add this content:

#!/bin/sh
case $1 in
config)
cat <<'EOM'
graph_category system
graph_title Temperature
graph_vlabel temp
temp.label Celsius
EOM
exit 0;;
esac
echo -n "temp.value "
cat /tmp/.temp

Save and exit the editor.

I’m not sure this is needed, but better do it: chmod +x temp

3) restart munin-node (/etc/init.d/munin-node restart)

4) test if it’s working:

# telnet localhost 4949
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
# munin node at industry.yeri.be
fetch temp
temp.value 57.3
.

That’s it. Your munin daemon/host should now correctly graph the temperature.

Edit (8/2/2014): updated script can be found here.