Debugging Apache

Most people get overwhelmed at the idea of debugging apache from the commandline, since there are multiple child processes involved, and each one handles who-knows-how-many requests.

But... it can be done!

First, from your local machine, figure out what the server will see as your IP address.  http://ipv4.icanhazip.com/

On the server, in the shell you'll be using to strace apache, enter:
export MYIP=1.2.3.4
...replacing 1.2.3.4 with the output you got from icanhazip.  That'll set the MYIP environment variable to your remote IP address.

From your local computer, at a commandline, telnet to the server, port 80.  Type in:
GET / HTTP/1.1
then hit enter.  Then type in:
Host whateverdomain-dot-com
...replacing that with your actual domainname of course.  And hit enter.  ONCE.

Then, on the server, run the following:
strace -s 999 -p `netstat -ntp|grep $MYIP|grep httpd|awk '{print $7}'|sed 's/\/.*//'`
That'll start strace up.  It should show that apache child waiting for input.

Back on your local machine, hit one more enter.  That ends the "GET" request.

On the server, you should see the debug strace of apache as it processes that GET request for you.

You'll have to control-C it when it's clear it's now done with your request and gone on to handling some other one.... but the beginning of that strace output will show you exactly what apache did to handle your request.