Windows: Monitoring of files or directories and alert when older than certain age

Written by Claudio Kuenzler - 0 comments

Published on March 21st 2018 - last updated on April 13th 2021 - Listed in Windows Monitoring Icinga Nagios

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On a Windows server, a service was hanging and nobody noticed it. The application team found out that this service, when working correctly, always creates certain temporary folders which disappear after a few minutes. This can be monitored, of course!

As the Windows servers have NSClient installed, I can use check_nrpe from the Icinga server to check for the folders. So I created a folder "claudiotest" in the temp folder of the application:

Basic check: Does such a folder exist?

Note that I used an asterisk wildcard in the path in order to simulate the temporary folders of the application, they all start with the same name but have a different ending.

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudio*"
OK: All 1 files are ok|

Indeed, there was one file found (my folder "claudiotest").

What if I search for another name?

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudiooo*"
No files found|

No surprise, nothing was found with that name.

Advanced check: Check if file age is older than 15min (=900s).

So here I had to add filters to limit my search result. I only wanted to have results matching the filename (C:\Program Files\Application\tmp\claudio*) and an age older than 15 minutes:

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudio*" "filter=age>900"
OK: All 1 files are ok|

So far so good, but it should not be OK, it should WARN that the application is probably hanging. For this the "warn" argument must be used:

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudio*" "filter=age>900" "warn=count>0"
WARNING: 1/1 files (claudiotest)|'count'=1;0;0

This means: As soon as the check found at least one file matching the filename and the age is older than 15min, it will return a warning.

What if file or directory does not exist?

But I faced one more issue. When no such directories exist (which can happen), I got an UNKNOWN return code (3):

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudiooo*" "filter=age>900" "warn=count>0"; echo $?
No files found|'count'=0;0;0
3

This means, that in Icinga this would be shown as an UNKNOWN alert, which should not be the case. But this can be solved with the parameter "empty-state". This basically means when nothing applies to the filter (no result), this return code should be used:

 $ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudiooo*" "filter=age>900" "empty-state=ok" "warn=count>0"; echo $?
No files found|'count'=0;0;0
0

This time, the return code was OK (0).

And the final check:

$ /usr/lib/nagios/plugins/check_nrpe -H windowsserver -c check_files -a "file=C:\Program Files\Application\tmp\claudio*" "filter=age>900" "empty-state=ok" "warn=count>0"
WARNING: 1/1 files (claudiotest)|'count'=1;0;0

Solved!

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