Localcheck input counter - calculate difference from previous check result

Checkmk Exchange
1

I am currently in the process of developing a Localcheck.
One of the results is a counter, which will increment over time, producing a steady inceasing line in a/the graph.

The thing is, that i am not interested in the counter by itself, but rather the difference of the counter compare to the previously received result.

As this involves comparing looking at the result of a previous poll to the last pull (IMHO) this should/would be handled by the CMK server itself (as that has/retains the data of a/the previous pull)

I have been digging thru docs and forum to find if this is possible, but either i am overlooking it, or its not there.

So general questions are:

  • Is there such a function/possibility implemented ?
  • if so any examples ?
  • if not, any alternatives as to achieving my goal ? → do take in mind that it is my goal to convert this check into a special agent.

Hope to hear back/ your input on this matter.

  • Glowsome
2

If you go the way to the special agent (or agent plugin) you can use get_rate() in the check plugin.

It is available in the check API v1 and v2.

1 Like
3

Hi,

good to know that there is a way when i go for a/the special agent, but until then, is it possible for a localcheck( still far away from going from a localcheck to a special agent)?

  • Glowsome
4

Currently, this is not possible.

I have filed a proposal for an extension of the local check plugin to handle counter values to the Checkmk feedback address some years ago, but it was not considered.

Edit: this was FEED-3636 from May 26 2019 in the tribe29 Jira issue tracker.

5

No, for local checks currently no such function exists. Maybe because it’s trivial to write one or because local checks can be written in any language, e.g. bash, python, or even C++, and they didn’t know what language to use.

In bash a simple function might look like this:

#!/usr/bin/env bash

get_delta() {
    current_value=$1
    counter_file=/var/tmp/mycounter.txt

    # read old value from file or default to "0" if that fails:
    old_value=$(cat $counter_file 2>/dev/null || echo 0);

    # store new value:
    echo $current_value > $counter_file;

    # return the delta:
    echo $(( current_value - old_value ))
}

################

new_value=5;
delta=$( get_delta $new_value )
echo "The delta is $delta"
1 Like
6

All of the above, but especially the last part. :slight_smile:

1 Like