Normaly when you are troubleshooting an Apache server you are checking parameters that don’t have monitors for them.
With the “observate” aproach the best place too look at is:
# tail -f /var/log/apache/access.log
Things to check:
200 OK requests are being served: This seems an obvious thing, you can see if there are normal traffic, or you can detect which pages are being accessed more, etc.
50x server responses are not happening: May be there are some pages that are returning server error, may be you didn’t know it, but someone somewhere is getting errors from your page. If there are only a few 50x errors, it is not a problem to ignore, may be this error is happening when a critical process is being done(registering, updating), I suggest zero tolerance for 50x errors.
404 server response are not being happening: If so it means that people are trying to access a non existant page, Sys admin will say this is not its responsability, sure It is a problem of the content but It is a problem for your customers, face it!
Let’s do in a basic way with:
# tail -f /var/log/apache/access.log|egrep '404|500|503|504'
But there is an advaced tool that read the logs and give you insights regarding the response codes, this tool is
Apachetop, it allows you to overlook, after that for more details you have the real logs, tail and grep as your friends.
On next post we will descrive other tools and techniques to check and test and monitor apache web servers, but we wanted to start with this “observate aproach”.
