Update raspberrypi sensor discovery to check for sensor existance #5114

merged 1 commit into from Dec 7, 2016


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jquagga commented Dec 5, 2016

Please note

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I recently added a RaspberryPi to my network to convert a USB UPS into a Network UPS. As part of that I added snmp to the Pi and added it to my librenms install. What I found is that the existing discovery code for the Pi just assumes that the snmp extend for raspberry.sh is enabled. It discovers sensors which on my install, had no data and it made for a messy page. So I offer this patch for consideration.

It looks like 2 of the 4 sensors have code to validate the data before discovering the sensor, but only one of those works (temperature). So these patches add if code to confirm we get something good back before discover_senors(). It's using is_numeric for all of the numeric sensors and for the codecs, I'm using stripos for "abled" since the options are enabled / disabled.

My main use for this is that is allows me to run my own raspberry.sh snmp extend which only provides temperature data and doesn't require root/sudo. I didn't want to give those permissions to the script/ run vcgencmd on the pi and this patch works nicely to enable that. Also this is a headless box where I'm never going to change the voltage or enable codecs so didn't want to bother polling that.

The attached screenshot shows the existing behavior with a snmp extend only providing temperature data, then the same situation after this patch (the unused sensors disappear). Finally the bottom screenshot is after this patch is applied with a "stock" snmp extend showing the sensors still polled and working.


This code should only run on raspberry pi discovery since it's already in an if block identifying the device as a RPI.

@jquagga jquagga Update raspberrypi sensor discover to check for sensor data
Presently the discovery code enables the raspberry pi snmp extend
sensors without checking to see if the snmp extend has actually
happened.  This adds appropriate checks to make sure that's happened
before enabling the sensor in librenms.

The inspection completed: 1 new issues

@@ -31,7 +31,7 @@
$value = snmp_get($device, $oid.$codec, '-Oqv');
- if (!empty($value)) {
+ if (stripos($value, 'abled') !== false) {
laf Dec 5, 2016 Member

What output is this trying to match out of interest?

jquagga Dec 6, 2016 Contributor

@laf The options are "enabled" or "disabled" for the codec:

ra:~% dash raspberry.sh 

That's the full output of a "normal" raspberry.sh snmp extension. That's the "stock" output on a RPI which hasn't had any of the extra codec's purchased. It's a headless system so they aren't needed.

jquagga Dec 6, 2016 Contributor

I can also modify the stipos() if statement to if ($value = 'enabled' || $value = 'disabled') if the goal was to have some tighter checking on the line.

laf Dec 7, 2016 Member

No I'm fine with it as is :)

@laf laf merged commit 28e35ef into librenms:master Dec 7, 2016

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@laf laf added the Bug label Dec 7, 2016
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