How to install/uninstall memcached extension for Plesk PHP 7.x handlers?

Warning: This is a process that it is done at your own will and risk which is not supported by Plesk.

Note: Memcached extension is only available/supported up to PHP 7.1

Since Memcached extension is not included in Plesk PHP packages, it can be installed manually: 

1. Log into the server via SSH and prepare the environment:

   For rpm-based OS (CentOS, RHEL, CloudLinux)

   # wget -q -O – http://www.atomicorp.com/installers/atomic | sh
   # yum install make memcached gcc libmemcached-devel zlib-devel plesk-php*-devel

   Note: Atomic repositories are being used instead of the CentOS ones because of newer package versions

   For deb-based OS (Debian, Ubuntu)

   # apt install memcached
   # apt install autoconf automake gcc libmemcached-dev libhashkit-dev pkg-config plesk-php..-dev zlib1g-dev

2. Perform the memcached installation for PHP 7.x:

   Note: in the example below, instructions for PHP 7.1 are provided. Replace ‘7.1’ with the required PHP version

   # /opt/plesk/php/7.1/bin/pecl install memcached

   Warning: Only for CentOS 6: Before proceeding with this step check the following

   Check the binaries that are going to be used for CentOS 6

   Be sure that the binaries used by the process are from the newer version available on the server by linking them as follow (The example below is for version 2.68):

   # mv /usr/bin/autoconf{,.bkp}

   # ln -s /usr/bin/autoconf268 /usr/bin/autoconf

   # mv /usr/bin/autom4te{,.bkp}

   # ln -s /usr/bin/autom4te268 /usr/bin/autom4te

3.  Register extension in configuration file:

   # echo “extension=memcached.so” > /opt/plesk/php/7.1/etc/php.d/memcached.ini

4.  Update PHP handlers information:

   # plesk bin php_handler –reread

5. Restart Apache and PHP-FPM services at Plesk > Tools & Settings > Services Management