How to Install Memcached (Caching Server) on CentOS 7

Memcached is an open-source distributed memory object caching program that allows us to improve and speed up the performance of dynamic web applications by caching data and objects in Memory.

Memcached is also used to cache entire database tables and queries to improve the performance of the database. It is the only caching system available freely and used by many big sites like YouTube, Facebook, Twitter, Reddit, Drupal, Zynga, etc.

Read Also: How to Install and Configure Memcached on CentOS 8

Memcached can commit to denial of service attacks if not correctly configured. In this article, we will explain how to install and secure your Memcached server on CentOS 7 Linux distribution. These given instructions also work on RHEL and Fedora Linux.

Installing Memcached in CentOS 7

First, update your local software package index and then install Memcached from the official CentOS repositories using following yum commands.

# yum update
# yum install memcached
Install Memcached in CentOS 7
Install Memcached in CentOS 7

Next, we will install libmemcached – a client library that offers a couple of tools to manage your Memcached server.

# yum install libmemcached
Install Memcached Library in CentOS 7
Install Memcached Library in CentOS 7

Memcached should now be installed on your CentOS system as a service, along with the tools that required you to test its connectivity. Now we can proceed further to secure its configuration settings.

Securing Memcached Configuration Settings

To make assure that installed Memcached service is listening on the 127.0.0.1 local interface, we will alter the OPTIONS variable in the /etc/sysconfig/memcached configuration file.

# vi /etc/sysconfig/memcached

Search for the OPTIONS variable, and add the -l 127.0.0.1 -U 0 to OPTIONS variable. These configuration settings will protect our server from denial of service attacks.

/etc/sysconfig/memcached
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS="-l 127.0.0.1 -U 0" 
Secure Memcached Configuration
Secure Memcached Configuration

Let’s discuss each of the above parameters in detail.

  1. PORT : The port used by Memcached to run.
  2. USER : The start-up daemon for Memcached service.
  3. MAXCONN : The value used to set max simultaneous connections to 1024. For busy web servers, you can increase to any number based on your requirements.
  4. CACHESIZE : Set cache size memory to 2048. For busy servers, you can increase up to 4GB.
  5. OPTIONS : Set the IP address of the server, so that Apache or Nginx web servers can connect to it.

Restart and enable your Memcached service to apply your configuration changes.

# systemctl restart memcached
# systemctl enable memcached

Once started, you can confirm that your Memcached service is bound to the local interface and listening only on TCP connections using following netstat command.

# netstat -plunt
Verify Memcached Server
Verify Memcached Server

You can also check the stats of the server using memcached-tool as shown.

# memcached-tool 127.0.0.1 stats
Check Memcached Running Status
Check Memcached Running Status

Now make sure to allow access to the Memcached server by opening a port 11211 on your firewall as shown.

# firewall-cmd --permanent --zone=public --add-port=11211/tcp

Install Memcached PHP extension

Now, install a PHP extension to work with the Memcached daemon.

# yum install php-pecl-memcache

Install Memcached Perl Library

Install Perl library for Memcached.

# yum install perl-Cache-Memcached

Install Memcached Python Library

Install python library for Memcached.

# yum install python-memcached

Restart Web Server

Restart the Apache or Nginx service to reflect changes.

# systemctl restart httpd
# systemctl restart nginx

Cache MySQL Queries with Memcached

It isn’t an easy task for all, you need to use API’s to modify your PHP codes to enable MySQL caching. You can find the examples codes at Memcache with MySQL and PHP.

That’s It! In this article, we have expanded how to install and secure your Memcached server to the local network interface. If you have faced any issues during installation, do ask for help in our comment section below.

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15 thoughts on “How to Install Memcached (Caching Server) on CentOS 7”

  1. Hi, I try your guide to activate Memcache on moodle, but moodle cannot activate the plugin. Turns out I must do: “yum install php-pecl-memcached”(with “d”), while the guide only mention “yum install php-pecl-memcache” (without “d”).

    I think it’s because when I try it, moodle 3.8 uses the newer version. nevertheless, moodle docs (https://docs.moodle.org/38/en/Caching) links to this page and I think you should know.

    OS: Centos 7, apache, php-fpm, and moodle 3.8.1.

    overall, thanks for the guide.

    Reply

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