Monthly Archives: May 2015

WordPress

CloudFlare Page Rules for WordPress Caching

CloudFlare only caches static content like css, jpg, etc. by default to enable faster load times for your site; however you can take advantage of Page Rules to make CloudFlare cache everything including the HTML. The problem with enabling this level of caching for WordPress is that it will cache:

  • The entire wp-admin section allowing a non-privileged user to load the admin site by typing in the URL
  • Preview URLs when you’re drafting a new page/post making it difficult to see your changes
  • wp-login.php getting you stuck in a redirect loop so you can’t login.

As a CloudFlare Free user, you will only have 3 Page Rules to work with; one will turn on caching of everything, leaving you with two rules to disable caching of the admin section, preview urls, and wp-login.php.

You could make a Page Rule with the pattern *domain.com/wp-* to prevent caching of both /wp-admin/ and wp-login.php; this leaves you with one rule left to prevent preview url caching with the pattern *domain.com/*preview=true*. However the pattern *domain.com/wp-* will also prevent caching of your static content since it matches the WordPress wp-content folder where most of it is located.

To solve this problem I used the WordPress plugin Rename wp-login.php to change my login URL to https://blog.thirdechelon.org/wp-admin[randomstring]/ – now you can prevent caching of the login page and admin sections with a single rule using pattern *domain.com/wp-admin* and you’ll still have two rules left to prevent caching of previews and to enable full caching of everything.

Below are the Page Rules I use for caching this blog (order matters); you’ll also want to install the WordPress Sunny Plugin to purge CloudFlare’s cache automatically when you make updates.

pagerule1pagerule2

Linux

CentOS MotD Generator

Recently a friend of mine showed me the cool MotD message he set up on his Ubuntu server that displays upon ssh login; it displays useful information such as OS & kernel version, uptime, system load, memory usage and other system stats. After some searching I found a MotD generator for CentOS here; it’s made up of two scripts: count_yum_updates.sh and generate_motd.sh. As the names imply, the first script counts the number of yum updates available, whose output will be read by the second script when it creates the MotD banner. Below are the instructions I’ve adapted from the author’s site on how to install it.

Install the dependencies for the scripts:

Download the scripts and make them executable:

Test the scripts to see if they work correctly:

If everything works, you should see similar output to below:

centos_motd

Copy scripts to their final locations:

Make a cron job to run count_yum_updates.sh automatically (adjust for your own preferred interval):

Now you’ll get a nice MotD whenever you log in with ssh. These scripts worked perfectly fine on a CentOS droplet at Digital Ocean but at RamNode the MotD did not display the IP address of the server. I’m not sure if it was because they were OpenVZ or not but I fixed the issue by modifying line 80 of generate_motd.sh:

Original line 80:

Modified: