Install multiple PHP versions with Apache on Debian

Update the repository cache.

sudo apt update

Install the below packages:

sudo apt install -y curl wget gnupg2 ca-certificates lsb-release apt-transport-https

Import the public using the below commands:

wget https://packages.sury.org/php/apt.gpg
sudo apt-key add apt.gpg

Add the sury repository to your system:

echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/php-sury.list

Update the repository index:

sudo apt update

Next install libapache2-mod-fcgid. This starts a number of CGI program instances to handle concurrent requests:

sudo apt install libapache2-mod-fcgid

Install PHP 5:

sudo apt install php5.6 php5.6-fpm php5.6-mysql libapache2-mod-php5.6

Install php 7:

sudo apt install php7.4 php7.4-fpm php7.4-mysql libapache2-mod-php7.4

Install PHP 8:

sudo apt install php8.2 php8.2-fpm php8.2-mysql libapache2-mod-php8.2

Once installed, you should have 3 new sockets in /var/run/php/

$ ls -la /var/run/php/*.sock
srw-rw---- 1 www-data www-data  0 Mar 12 18:29 /var/run/php/php5.6-fpm.sock
srw-rw---- 1 www-data www-data  0 Mar 12 18:30 /var/run/php/php7.4-fpm.sock
srw-rw---- 1 www-data www-data  0 Mar 12 18:30 /var/run/php/php8.2-fpm.sock

Start PHP-FPM Services:

sudo systemctl start php5.6-fpm
sudo systemctl start php7.4-fpm
sudo systemctl start php8.2-fpm

Configure Apache. We need to add some Apache modules using a2enmod:

• actions – used for executing CGI scripts based on media type or request method.
• fcgid – a high performance alternative to mod_cgi that starts a sufficient number of instances of the CGI program to handle concurrent requests
• alias – provides for the mapping of different parts of the host filesystem in the document tree, and for URL redirection
• proxy_fcgi – allows Apache to forward requests to PHP-FPM

sudo a2enmod actions fcgid alias proxy_fcgi
sudo systemctl restart apache2

Remove default files:

rm /etc/apache2/sites-enabled/000-default.conf

Create a new virtualhost at /etc/apache2/sites-enabled/php56.conf:

<VirtualHost *:80>
    ServerName www.examplephp56.com
    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html/php56
    >FilesMatch \.php>
        SetHandler "proxy:unix:/var/run/php/php5.6-fpm.sock|fcgi://localhost/" 
    </FilesMatch>
</VirtualHost>

Make test dirs:

mkdir -p /var/www/html/php56

and file /var/www/html/php56/info.php with contents:

<?php
phpinfo();

Add to /etc/hosts locally:

127.0.0.1 www.examplephp56.com

or on remote machine:

x.x.x.x www.examplephp56.com

where x.x.x.x is the IP address of machine where all was installed
Restart Apache:

systemctl restart apache2

and test using curl or browser if you are testing remotely:

curl www.examplephp56.com/info.php|grep ">PHP Version <"

For PHP 7 - procedure is the same, just use the following snippet

<FilesMatch \.php>
  SetHandler "proxy:unix:/var/run/php/php7.4-fpm.sock|fcgi://localhost/" 
</FilesMatch>

And for PHP 8:

<FilesMatch \.php>
  SetHandler "proxy:unix:/var/run/php/php8.2-fpm.sock|fcgi://localhost/" 
</FilesMatch>