Setup Apache, FastCGI and PHP 7.4 on Ubuntu 20

Prerequisites

Update the installed packages.

apt update

Install the Ondřej PHP repository.

apt install software-properties-commonsudo
add-apt-repository ppa:ondrej/php
apt update

Check that the repositories are correctly installed.

grep ^ /etc/apt/sources.list /etc/apt/sources.list.d/*

Step 1 – Install Apache

apt install apache2

Step 2 – Install the PHP versions

In this case, php 7.4 will be installed

# PHP 7.4
apt-get install php7.4 php7.4-bcmath php7.4-dev php7.4-cli php7.4-cgi php7.4-common php7.4-gd php7.4-json php7.4-mbstring php7.4-xml php7.4-zip

Step 3 – Install FastCGI

# Ubuntu 16.04
apt install libapache2-mod-fastcgi
# Ubuntu 18.04 or Ubuntu 20
apt install libapache2-mod-fcgid

Step 4 – Setup the FastCGI handler for each PHP version

Two handlers will be created, one for each PHP version installed.

# PHP 7.4
vim /var/www/cgi-bin/php74.fastcgi
chmod +x /var/www/cgi-bin/php74.fastcgi
chown www-data:www-data /var/www/cgi-bin/php74.fastcgi

php74.fastcgi

#!/bin/bash
PHPRC="/etc/php/7.4/cgi/php.ini"
PHP_FCGI_CHILDREN=4
PHP_FCGI_MAX_REQUESTS=1000
export PHPRC
export PHP_FCGI_CHILDREN
export PHP_FCGI_MAX_REQUESTS
exec /usr/lib/cgi-bin/php7.4

Step 5 – Configure the sites

Change directory to the default web directory.

# Ubuntu 16.04
cd /var/www
# Ubuntu 18.04 or Ubuntu 20
cd /var/www/html

Create the folders each site.

mkdir php70-example

Create the index files for each site.

vim php74-example/index.php

index.php
<?php phpinfo(); ?>

Step 6 – Setup the virtual hosts

cd /etc/apache2/sites-available
vim php74-example.conf

php74-example.conf

<VirtualHost *:80>
ServerName php74-example
ServerAdmin php74-example@example.com
DocumentRoot /var/www/html/php74-example
ScriptAlias /cgi-bin/ "/var/www/cgi-bin/"
<Directory "/var/www/html/php74-example">
Options +Indexes +FollowSymLinks +ExecCGI
AddHandler fcgid-script .php
FCGIWrapper /var/www/cgi-bin/php74.fastcgi .php
AllowOverride All
Order allow,deny
Allow from All
</Directory>
</VirtualHost>

Step 7 – Configure Apache

Disable the default PHP modules.

a2dismod php*

Enable the necessary modules

a2enmod actions alias fcgid proxy_fcgi rewrite

Disable the default site.

a2dissite 000-default

Enable the corresponding sites

a2ensite php74-example

Step 8 – Restart Apache

/etc/init.d/apache2 reload

Step 9 – Setup the firewall

sudo ufw allow 'Apache'
sudo ufw allow 80/tcp
sudo ufw allow 81/tcp
sudo ufw disable
sudo ufw enable

Src:

How to Install Multiple PHP Version with Apache on Debian 11/10

https://www.howtoforge.com/how-to-set-up-apache2-with-mod_fcgid-and-php5-on-ubuntu-12.04