How to create monit monitor to alert when a line of text is NOT seen in a log file over a period of time

Question

I can see how to alert when a regex appears in a log file. I can see how to alert when a regex does not appear on EVERY line of a log file. But I can't see how to alert when a regex has not appeared in a log file over a period of time.

I could create a bash script which regex's the file for me, and writes out to a file which monit monitors, but would rather keep the solution within monit.

Any help would be appreciated.

Answer 1

From the manual:

IF [NOT] MATCH {regex|path} [[] CYCLES] THEN action

The content is only being checked every cycle. If content is being added and removed between two checks they are unnoticed.

Use the CYCLE option. The limitation I see here is the cycles. The manual defaults to 300 seconds (5 minutes). Determine how many cycles are needed and then tweak the alerting.