What is PHP-FPM on an Ubuntu VPS

PHP-FPM (FastCGI Process Manager) is an advanced version of PHP's FastCGI implementation. It provides a faster and more efficient way of serving PHP scripts, with features like process management, adaptive spawning, and better handling of dynamic content. PHP-FPM is highly preferred for high-traffic websites because it can handle more requests with fewer resources compared to traditional mod_php setups. PHP-FPM is often used in conjunction with web servers like Nginx or Apache and helps optimize the performance of PHP applications by managing multiple PHP processes efficiently.

Installing PHP-FPM on an Ubuntu VPS

Here’s a step-by-step guide to installing PHP-FPM on an Ubuntu VPS, along with an example of how to use it with Nginx.

Before installing any software, it’s important to ensure that your system is up-to-date:

On Ubuntu, PHP-FPM comes as part of the PHP package. To install PHP-FPM along with PHP, run the following command:

This installs both PHP and the FastCGI Process Manager (FPM) for managing PHP processes.

The main PHP-FPM configuration file is located at /etc/php/7.x/fpm/php.ini (the version number may vary depending on the PHP version installed). You can edit this file to fine-tune PHP settings.

For basic setup, the default configuration is usually sufficient, but you can adjust the following options if needed:

After making changes, save the file and restart PHP-FPM to apply the settings:

PHP-FPM is commonly used with Nginx because Nginx does not have native PHP support like Apache. Follow these steps to configure Nginx with PHP-FPM.

Step 1: Install Nginx

If Nginx isn’t already installed, use the following command to install it:

Step 2: Configure Nginx to Use PHP-FPM

To make Nginx process PHP files using PHP-FPM, you need to modify the server block configuration file for your website. This file is typically located in /etc/nginx/sites-available/.

For example, edit the default Nginx site configuration:

Find the section for the server block and add the following configuration to enable PHP processing with PHP-FPM:

In the configuration above:

- fastcgi_pass: This line directs Nginx to use PHP-FPM for processing .php files. The php7.x-fpm.sock socket corresponds to the version of PHP installed.

Save the file and exit the editor.

Step 3: Test and Restart Nginx

After making changes to the configuration file, test Nginx to ensure there are no syntax errors:

If the test is successful, restart Nginx to apply the changes:

To verify that PHP-FPM is working correctly with Nginx, create a simple PHP file and place it in your web root directory:

Add the following PHP code to the file:

Save and close the file. Now, open a browser and navigate to http://yourdomain.com/info.php. You should see a PHP information page, confirming that PHP-FPM is working correctly with Nginx.

By default, PHP-FPM creates a single pool of processes to handle requests. You can create multiple pools to better manage traffic for different websites or applications. Each pool can have its own configuration, including settings like memory limits, max children, and more.

To create or modify pools, edit the pool configuration file located at:

Here, you can configure specific parameters for the pool:

You can also create separate pool configurations for different applications by copying the www.conf file and customizing it:

Then edit the new pool configuration as needed.

After any changes, restart PHP-FPM to apply them:

PHP-FPM logs can be found at /var/log/php7.x-fpm.log. To monitor how PHP-FPM is handling requests and check for issues, tail the log:

This will show real-time logging information, which can help you troubleshoot performance problems or misconfigurations.

Example of Using PHP-FPM in a Web Application

Let’s say you’re running a WordPress site with Nginx and PHP-FPM. When a visitor requests a page, Nginx will check if the requested page exists. If it’s a static file (like an image or CSS), Nginx serves it directly. If the request is for a PHP page (like index.php), Nginx passes the request to PHP-FPM for processing.

Here’s how the process works:

This separation between the web server (Nginx) and the application server (PHP-FPM) ensures efficient handling of requests, with PHP-FPM focusing solely on executing PHP code.

PHP-FPM is a powerful and efficient way to manage PHP processes, especially for high-traffic websites. By following this guide, you can install PHP-FPM on your Ubuntu VPS, configure it with Nginx or Apache, and optimize your server for better performance. Whether you're running a simple blog or a complex web application, PHP-FPM can handle your PHP processing needs efficiently.