Speeding Up OpenCart with Redis on a Plesk Server

June 27, 2025

Recently, I decided to improve the performance of an OpenCart store by switching the caching engine to Redis. It turned out to be a worthwhile upgrade, but not without a few hurdles along the way.

Why Redis?

Redis is an in-memory data store often used for caching. It offers fast read/write performance, which helps make OpenCart faster and more scalable, especially for stores with lots of products or traffic.

Installing Redis on a Plesk Server

On a CentOS/RHEL-based server with Plesk, I installed Redis using yum:

yum install redis

After installation, I enabled and started the Redis service:

systemctl enable redis
systemctl start redis

Confirmed it’s running:

systemctl status redis

You may also need the PHP Redis extension (in my case it was already installed for PHP 8.1):

yum install php-pecl-redis

Then restart your web server and PHP:

systemctl restart httpd # For Apache
systemctl restart nginx # If you're using Nginx
systemctl restart php-fpm # Replace with your actual PHP-FPM version

Configuring OpenCart to Use Redis

Next, I told OpenCart to use Redis for caching.

Opened the following file:

system/config/default.php

Find this line:

$_['cache_engine'] = 'file'; // apc, file, mem or memcached

Change it to:

$_['cache_engine'] = 'redis'; // apc, file, mem or memcached

In addition, I had to define the Redis host, port, and prefix. Add the following lines to both of your configuration files:

config.php (main store)
admin/config.php (admin panel)

define('CACHE_HOSTNAME', '127.0.0.1');
define('CACHE_PORT', '6379');
define('CACHE_PREFIX', 'oc_');

Make sure the IP matches the internal Docker/bridge IP if you’re using containers, or 127.0.0.1 if Redis is local and accessible that way.

Solving an Issue: Redis Process Killed by lfd

After everything seemed fine, Redis would mysteriously stop after a few minutes. Logs showed that lfd (Login Failure Daemon) was killing it, mistaking Redis for a suspicious or abusive process.

Solution: Add Redis to the lfd Ignore List

To fix this, I needed to whitelist Redis in csf:

Edited the process ignore file:
```
nano /etc/csf/csf.pignore
```
Added this line:
```
exe:/usr/bin/redis-server
```
Restarted CSF and lfd:
```
csf -r
systemctl restart lfd
```

This prevented lfd from killing Redis, and it’s been running reliably since.

Switching to Redis gave this OpenCart store a noticeable speed boost. The process was mostly straightforward, but required some tweaking to ensure stability on a Plesk server especially around lfd behavior and the need to define the cache host and port explicitly.

If you’re looking to improve OpenCart performance and you’re comfortable with server-side changes, Redis is definitely worth trying.