Category: The Fancy Robot

Set Up Redis Object Cache for WordPress

When it comes to WordPress speed optimizations, there are plenty of options. In fact, it can be a bit overwhelming trying to figure out what the best options are. The average WordPress user goes straight for one of the many plugins, such as W3 Total Cache, WP Rocket, or SP Super Cache. I hate to say it, but your best option is to not use any of them. the issue with those plugins, aside from the security issues (boy have I seen some real messes because of those plugins), is that they are all PHP level solutions. The best solution to speed up WordPress is to use technologies that exist outside of the WordPress ecosystem. Enter Redis

Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker.

So what does that mean? It means that we can store data that WordPress queries from the database in Redis for quick and easy access, and it’s a persistent data store. This speeds up your site, and greatly reduces server load, by storing all of that data so that WordPress doesn’t have to run multiple queries to the database every time a page is loaded. We call this an object cache.

What’s Wrong With the Built-in WordPress Object Cache?

This question could be answered with a whole new article. Thankfully, Zack Tollman has already written it. It’s a little dated and refers to Memcached instead of Redis, but the overall point of the article still applies today. To sum up, there isn’t anything wrong with the built-in object cache, but a persistent cache is more efficient.

Step 1 – Install Redis

This tutorial assumes you have your site set up on an Ubuntu or Debian server.

We’re going to install Redis using apt. This is the easiest method and it ensures you’re using a stable version. Before installing anything you should always make sure apt is up to date by typing:

sudo apt-get update && apt-get upgrade

Now it’s time to install Redis

sudo apt-get install redis-server

Now you need to check the configuration. Unless you know for a fact that your situation is different, you want to make sure that Redis is only available to localhost. This should be the default configuration but check it anyway just to be sure. This is a very important security measure.

sudo nano /etc/redis/redis.conf

Find this line and remove the # if there is one at the beginning of the line. Make sure there are no other bindings in the configuration.

bind ::1

Then add this to the end of the file

maxmemory 50mb
maxmemory-policy allkeys-lru

Please note: you can increase the maxmemory setting according to your needs, but 50mb will be plenty for most WordPress installs

Save the Redis configuration file and restart Redis

sudo systemctl restart redis

And make sure your configuration is correct

sudo netstat -lnp | grep redis

You should see output similar to this:

tcp    0    0*    LISTEN    6888/redis-server 1

If there is more than one line in the output, check your configuration and make sure that is the only binding in the configuration.

Step 2 – Install WP Object Cache plugin

There are a couple Redis object cache plugins, but the Redis Object Cache plugin is the easiest to set up.

Install the plugin using the standard procedure for install WordPress plugins.

Now go to Settings > Redis and click the “Enable Object Cache” button.

Step 3 – Add salt to wp-config.php (optional)

This setting is really only important if you’ve got more than one resource accessing the same Redis data store (e.g. WordPress multisite install). However, I would recommend setting it anyway, if for no reason other than planning ahead in case you need to add an additional resource on your server in the future.

Open up your wp-config.php file and add this at the end (you can enter any string you want for the salt. I personally use to generate a random string)

define( 'WP_CACHE_KEY_SALT', 'cFGUIzDeyA' );

Make sure you flush and restart your cache after setting the key salt.

That’s all folks!

Now you’ve got a Redis object cache for your WordPress website. There are many configuration options for the plugin that are outside the scope of this article. Please visit for plugin documentation and support.

Please leave any questions, comments, or concerns in the comment section!

How to Create a Child Theme in WordPress

Let me start you off with a little story. My first job as a professional web developer, I was working in an agency developing custom WordPress websites. This meant that every time we had a new client, we built them a new theme from scratch. The problem with this is that we would have to download Underscores, strip out all of the stuff we didn’t need, and then add all the code to make the theme their own. The problem with this is that a lot of our sites shared the same logic, but we were writing it over and over again. This was an astronomical waste of time, but I didn’t know any better, because this was my first job as a web developer as well as the first time I ever built custom WordPress themes. What’s the solution? WordPress child themes.

What is a WordPress Child Theme?

From the Developer Handbook:

A child theme allows you to change small aspects of your site’s appearance yet still preserve your theme’s look and functionality. To understand how child themes work it is first important to understand the relationship between parent and child themes.

What is a Parent Theme?

A parent theme is a complete theme which includes all of the required WordPress template files and assets for the theme to work. All themes – excluding child themes – are considered parent themes.

What is a Child Theme?

A child theme inherits the look and feel of the parent theme and all of its functions, but can be used to make modifications to any part of the theme. In this way, customizations are kept separate from the parent theme’s files. Using a child theme lets you upgrade the parent theme without affecting the customizations you’ve made to your site.

Child themes:

  • make your modifications portable and replicable
  • keep customization separate from parent theme functions
  • allow parent themes to be updated without destroying your modifications
  • allow you to take advantage of the effort and testing put into parent theme
  • save on development time since you are not recreating the wheel, and
  • are a great way to start learning about theme development

Basically, it allows you to make changes to the theme without actually changing the theme (follow me?). You can customize your theme to your heart’s content, while still allowing changes/updates to the main, or parent, theme without breaking anything.

How Do I Create a Child Theme?

Easy peasy.

  1. In your wp-content/themes/ folder, create a new folder for your child theme. You can name it whatever you’d like.
  2. In that folder, create a file named style.css.
  3. In that file, put the following content:
     Theme Name:   Child Theme
     Theme URI:
     Description:  Child theme for
     Author:       The Fancy Robot
     Author URI:
     Template:     parent-theme
     Version:      1.0.0
     License:      GNU General Public License v2 or later
     License URI:
     Text Domain:  textdomain
  4. Be sure to change the parameters appropriately:
    • Theme Name: The name of your child theme. You can put anything in here, but don’t name it the same as any other theme you have installed.
    • Theme URI: The web address for your theme. In this case, just put the URI for your website.
    • Description: Description of your theme.
    • Author: THAT’S YOU!
    • Author URI: If you have a website separate from the one you’re currently working on, put that here.
    • Template: The directory of the parent theme.
    • License: The license for the code you’re writing. This isn’t absolutely necessary, but if you’re going to be sharing this code, or you’re developing for a client, I would include a license.
    • License URI: URI for the actual license text.
    • Text Domain: This is for translating your website. This is commonly just the name of your theme (all lowercase, and one word). I recommend adding this even if you don’t plan to implement translations.
  5. Create a functions.php file, and add any additional functionality you need in there.
  6. If you’d like an image to show on the theme selection page in the WordPress admin, just create an image and save it as screenshot.png in the root directory of your child theme.

And now you have a child theme. After activating the child theme in the WordPress admin and WordPress will load both your parent them and your child theme. Any template files in your child theme will now override the templates in the parent theme. This opens the door to a ton of custom functionality without worrying about updates to your parent theme breaking things.