Running WordPress from MySQL Cluster with HAPRoxy

SELinux was contributing to the problem. The main issue was that an HTML page was attempting to talk to another port on the localhost. I would not have seen the problem if the HAProxy was running on a separate host.

The log was revealed in /var/log/messages, where I should have checked but did not considering I didn’t expect it. Fail on my part. The log looked like this:

setroubleshoot: SELinux is preventing the http daemon from connecting to network port 3306 For complete SELinux messages.

SELinux should not have been running to begin with, so I simply disabled it:

echo 0 > /selinux/enforce

To maintain this state upon reboot, simply edit the SELINUX line in /etc/sysconfig/selinux to say SELINUX=permissive rather than SELINUX=enforced. This will log alerts but not stop any processes. To disable SELinux completely, just replaced it with SELINUX=disabled instead.