How to Install and Configure Memcached on Rocky Linux/Alma Linux 8

In this guide we will learn how to install and configure Memcached in RHEL 8 based systems like Rocky Linux and Alma Linux 8.

Memcached is an open source, distributed memory object caching system. The system caches data and objects in memory to minimize the frequency with which an external database or API must be accessed. This alleviates database load and speeds up dynamic Web applications. It offers a mature, scalable, open-source solution for delivering sub-millisecond response times making it useful as a cache or session store. Memcached is a popular choice for powering real-time applications in Web, Mobile Apps, Gaming, Ad-Tech, and E-Commerce.

Unlike databases that store data on disk or SSDs, Memcached keeps its data in memory. By eliminating the need to access disks, in-memory key-value stores such as Memcached avoid seek time delays and can access data in microseconds. Memcached is also distributed, meaning that it is easy to scale out by adding new nodes. And since Memcached is multithreaded, you can easily scale up compute capacity. As a result of its speed and scalability as well as its simple design, efficient memory management, and API support for most popular languages Memcached is a popular choice for high-performance, large-scale caching use cases.

Table of Content

Ensuring that the server is up to date
Installing Memcached
Start and enable memcached service
Enable Memcached on firewall
Configure memcached

1. Ensuring that the server is up to date

Before proceeding, it is always a good practice to ensure that the server packages are updated. Use this command to achieve that:

sudo dnf -y update

Let us also install common packages that we will need during our installation and configuration.

sudo dnf install -y vim

2. Installing Memcached

Memcached packages are available in the default Rocky Linux repositories. Install them using this command:

sudo dnf install -y memcached

Confirm the installation of memcached

$ rpm -qi memcached
Name        : memcached
Epoch       : 0
Version     : 1.5.22
Release     : 2.el8
Architecture: x86_64
Install Date: Sun 09 Jan 2022 03:52:09 PM UTC
Group       : System Environment/Daemons
Size        : 414743
License     : BSD
Signature   : RSA/SHA256, Mon 12 Apr 2021 07:04:12 AM UTC, Key ID 15af5dac6d745a60
Source RPM  : memcached-1.5.22-2.el8.src.rpm
Build Date  : Mon 12 Apr 2021 04:45:42 AM UTC
Build Host  : ord1-prod-x86build003.svc.aws.rockylinux.org
Relocations : (not relocatable)
Packager    : infrastructure@rockylinux.org
Vendor      : Rocky
URL         : https://www.memcached.org/
Summary     : High Performance, Distributed Memory Object Cache
Description :
memcached is a high-performance, distributed memory object caching
system, generic in nature, but intended for use in speeding up dynamic
web applications by alleviating database load.

3. Start and enable memcached service

Once the service is installed, it will not be started by default. Use this command to start the service

sudo systemctl start memcached

Confirm that the service is started with this command:

$ sudo systemctl status memcached
● memcached.service - memcached daemon
   Loaded: loaded (/usr/lib/systemd/system/memcached.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2022-01-10 02:59:15 UTC; 1min 32s ago
 Main PID: 54961 (memcached)
    Tasks: 10 (limit: 23176)
   Memory: 1.7M
   CGroup: /system.slice/memcached.service
           └─54961 /usr/bin/memcached -p 11211 -u memcached -m 64 -c 1024 -l 127.0.0.1,::1

Jan 10 02:59:15 rockysrv.citizix.com systemd[1]: Started memcached daemon.

The output above is a confirmation that Memcached is up and running.

To enable the service on boot

<meta charset="utf-8">sudo systemctl enable memcached

4. Enable Memcached on firewall

open port 11211 on the firewall to allow traffic from the client host.

$ sudo firewall-cmd --add-port=11211/tcp --zone=public --permanent
$ sudo firewall-cmd --reload

To confirm that port 11211 is opened on the firewall, execute the command.

$ sudo firewall-cmd --list-ports | grep 11211

5. Configure memcached

The memcached config is located in this path /etc/sysconfig/memcached. Use this command to open the file for editing.

sudo vim /etc/sysconfig/memcached

This is the default memcached configuration.

PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS="-l 127.0.0.1,::1"

By default, Memcached listens to port 11211 and is configured to listen only to the localhost system as shown in the final line. To configure Memcached so that applications from the remote systems can connect to the server, you need to change the localhost address 127.0.0.1 to the address of the remote host or to listen on all interfaces.

To use the remote host, replace the localhost address with the remote client’s IP 10.70.5.214 as shown.

<meta charset="utf-8">OPTIONS="-l <meta charset="utf-8">10.70.5.214,::1"

To listen on all network interfaces 0.0.0.0 instead of 127.0.0.1. Change the OPTIONS line to below.

 OPTIONS="-l 0.0.0.0,::1"

Once done configuring, restart the memcached server to apply the changes:

sudo systemctl restart memcached

Confirm the changes with this command

$ sudo ss -tulpn | grep 11211
tcp   LISTEN 0      128      10.70.5.214:11211      0.0.0.0:*    users:(("memcached",pid=55522,fd=28))
tcp   LISTEN 0      128            [::1]:11211         [::]:*    users:(("memcached",pid=55522,fd=29))

Wrapping up

That is it! In this guide, we learned how to install and configure Memcached server on a Rocky Linux 8 Server. You can now configure your applications to connect and use the Memcached instance.