I'd like to monitor the rate of 404, 403, 500 etc errors in my Apache logs with Munin but I can't find a plugin to do this. Surely it exists?
Here's a plugin that might help. It monitors various request codes by parsing the log files.
Near the top you can set the codes you care about:
mystatuscodes="400 401 403 404 500 503 504"
You can also configure how many recent log lines it looks at and what log file to parse.
To be honest you are probably better off writing your own plugin. It's really simple and you can customize it for your needs (for example, does your system use logrotate? etc.) – plus, you get to write your first munin plugin.
I did the same kind of monitoring for another service (spam filter), never with Apache. However, the idea is the same.
You have to code a little script which will parse the log files and analyze them. Munin will launch the script every like 5 minutes.
The script uses
logtail to keep track of unread lines.
With a bunch of
grep you will be able to count the lines depending of what HTTP code you're looking for.
I hope you get the point.
Sorry I can't give you the script, I moved to another company.