How to write a Bash Script for Pushgateway and prometheus - bash

Question

I am trying to use a bash script for Pushgateway and Prometheus, but can't get it working.
I have Pushgateway on my raspberry and Prometheus on another raspberry. All work correctly and I test a simple bash script, this script works correctly.
My simple script (test.sh):
echo "metric 99" | curl --data-binary #- http://localhost:9091/metrics/job/some_job
Now I want to write a more complex script. This script must push to prometheus the metric from CPU usage (the same as the "$ps aux" command or same as "$ top" command). But this script doesn't work and I don't know what to do to modify it..
My more complex script :
#!/bin/bash
z="ps aux"
while read -r $z
do
var=$var$(awk '{print "cpu_usage{process=\""$11"\", pid=\""$2"\"}", $3$z}');
done <<< "$z"
curl -X POST -H "Content-type: text/plain" --data "$var" http://localhost:9091/metrics/job/top/instance/machine
If anyone could help me. Thanks a lot.
I also try this code :
#!/bin/bash
z="ps aux"
while read -r "ps aux"
do
var=$var$(awk '{print "cpu_usage{process=\""$11"\", pid=\""$2"\"}", $3$z}');
done <<< "$z"
curl -X POST -H "Content-type: text/plain" --data "$var" http://localhost:9091/metrics/job/top/instance/machine
But I am not sure about the syntax. What's wrong ?
I try the code :
load=$(ps aux | awk '{ print "cpu_usage{ process=\"" $11 "\",pid=\"" $2 "\"}," $3 }')
curl -X POST -H --data "$load" http://localhost:9091/metrics/job/top/instance/machine
But it doesn't work. The first line is ok, but when i run this code, I find an error message to the curl command:
curl: (3) URL using bad/illegal format or missing URL
========== The solution to my problem is : ==========
ps aux | awk '$3>0 {print "cpu_usage"$2" "$3""}' | curl --data-binary #- http://localhost:9091/metrics/job/top/instance/machine
This command could transfer to the pushgateway all process data with % CPU > 0. In this line, $3 = %CPU, $2 = PID. Be carefull with special caracters. If the result command is an error message, maybe it is because there is special caracter...

Answer 1

If your problem is too complex, divide it into smaller, more manageable pieces and see what they do. Start by analysing output from the awk part.
AWK can be a bit of a handful.
Try a simpler approach:
ps aux | tr -s ' ' ',' | cut -d, -f2,11 |
while read pid process; do
req="cpu_usage{process=$process,pid=$pid}"
echo "Sending CURL Request with this data: $req"
curl -X POST -H "Content-type: text/plain" --data "$req" http://localhost:9091/metrics/job/top/instance/machine
done
You may want to review the brackets. I have no means of testing this.

Answer 2

You seem to be confused about several details of basic Bash syntax.
command <<<"string"
simply passes the literal string as standard input to command. The syntax you seem to be looking for is the process substitution
command < <(other)
which runs other and passes its output as input to command. But this too is an overcomplication; you probably want a simpler straight pipeline.
load=$(ps aux | awk '{ print "cpu_usage{ process=\"" $11 "\",pid=\"" $2 "\"}," $3 }')
curl -X POST -H "Content-type: text/plain" --data "$load" http://localhost:9091/metrics/job/top/instance/machine
where I had to resort to some wild speculation around what you hoped the Awk script should do.
Also, the argument to read is the name of a variable, so read z, not read $z (and usually use read -r unless you specifically require the odd legacy behavior of read with backslashes in its input).
Finally, you basically never want to store a command in a variable; see https://mywiki.wooledge.org/BashFAQ/050
Going forward, probably try http://shellcheck.net/ before asking for human assistance.

Answer 3

/!\ The solution to my problem is : /!\
ps aux | awk '$3>0 {print "cpu_usage"$2" "$3""}' | curl --data-binary #- http://localhost:9091/metrics/job/top/instance/machine
This command could transfer to the pushgateway all process data with % CPU > 0. In this line, $3 = %CPU, $2 = PID. Be carefull with special caracters. If the result command is an error message, maybe it is because there is special caracter...
Thanks...