Install and Setup Redis for Object Caching with WordPress on Ubuntu 16.04 | 18.04 | 18.10

When running WordPress sites you should always look for ways to enhance the sites’ performance by enabling caching and other performance boosting configurations…

This brief tutorial shows students and new users how to setup WordPress to use Redis for object caching to speed up database queries and PHP dynamic calls….

The first time a WordPress page is loaded a database query is made via PHP…. When using Redis, these queries can be stored into system memory so that when another user loads the same page there is no need to query the database again… Redis will retrieve the previously cached query results from memory…

Setting this will help improve WordPress performance…
To get started with enable Redis with WordPress support, please continue below:

The first thing is to have a working WordPress site… If you don’t have WordPress installed, then search our site for help installing WordPress..

We have covered WordPress installation with both Apache2 and Nginx support on this site….

Step 1: Install the Latest Redis Server

After installing WordPress, run the commands below to install the latest version of Redis…

The version of Redis server that comes with Ubuntu by default isn’t the latest… To install the latest version you will have to add the PPA below and install from there…

To do that, run the commands below:

sudo apt-get install software-properties-common

Once that package is installed, run the commands below to add the PPA that contains the latest version of Redis…

sudo add-apt-repository ppa:chris-lea/redis-server

After adding the repository, run the command below to install Redis…

sudo apt-get update
sudo apt-get install redis-server php-redis

Verify that you have version 4 of Redis installed with the following command:

redis-server --version

You should see Redis virsion installed on your system….

Step 2: Allocate Memory to Redis and Setup an Eviction Policy

Now that Redis is installed, run the commands below to open its configuration file…

sudo nano /etc/redis/redis.conf

Then uncomment the lines below to allow memory and an eviction policy… You’ll have to scroll through the lines to find these… Then set then up as shown below:

maxmemory 256mb
maxmemory-policy allkeys-lfu

Save the file and exit…

When you’re done run the commands below restart Redis and PHP… If you’re running Apache2, then just restart Apache2 and Redis server…

sudo systemctl restart redis-server
sudo systemctl restart php7.2-fpm

Step 3: Configure WordPress wp-config.php file

After the above steps run the commands below to open WordPress wp-config.php file in your WordPress root directory…

sudo nano /var/www/html/wordpress/wp-config.php

Then add these lines just below WordPress unique Keys and Salts section…

define( 'WP_CACHE_KEY_SALT', '' );
define( 'WP_CACHE', true );

After that, save the file and exit..

Step 4: Install a Redis Object Cache Plugin

The final step is to install WordPress Redis Object Cache Plugin… To do that navigate to the plugin page and install in WordPress…

WordPress Redis server plugin

After installing, activate and enable the plugin… When you’re done, go to the plugin settings page and if everything is configured correctly, you should see something similar to the image below:

WordPress Redis server install

That should do it!

Your WordPress setup should now use Redis object caching to help speed up your site…


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