Installing Apache Web Server on Debian 10

The Apache HTTP Web Sever (Apache) is an open source web application for deploying web servers. This guide explains how to install and configure an Apache web server on Debian 10.

If instead you would like to install a full LAMP (Linux, Apache, MySQL and PHP) stack, please see the How to Install a LAMP Stack on Debian 10 guide.

Before You Begin

1. Set up your Linode in the Creating a Compute Instance and Setting Up and Securing a Compute Instance guide.

2. If you want a custom domain name for your site, you can set this up using our DNS Manager guide.

   • Don’t forget to update your /etc/hosts file with the public IP address and your site’s fully qualified domain name as explained in the Update Your System’s hosts File section of the Setting Up and Securing a Compute Instance guide.
   Note

   This guide is written for a non-root user. Commands that require elevated privileges are prefixed with sudo. If you’re not familiar with the sudo command, visit our Users and Groups guide.

   All configuration files should be edited with elevated privileges. Remember to include sudo before running your text editor.

Install Apache

Install Apache 2.4:

sudo apt-get install apache2

Multi-Processing Modules

Apache 2.4 offers several multi-processing modules (MPMs) to handle connections. In Debian 10 the default MPM is the event module, although the prefork module is still recommended if you’re using standard PHP. Below are the basic default settings. For detailed explanations and advanced settings for these modules, see the Tuning Your Apache Server guide.

1. You can check which MPM is currently configured with the following command:

   sudo apachectl -V | grep -i mpm
   

   Server MPM:     event

The Prefork Module

The Prefork Module is ideal for single threaded applications. It’s a single parent with multiple forked child servers that are identical processes that wait for incoming requests. Each child process handles a single request. The Prefork Module is resource intensive but necessary for applications that do not support multi-threading such as PHP.

1. Open /etc/apache2/mods-available/mpm_prefork.conf in your text editor and edit the values as needed. The following are the default values:

   File: /etc/apache2/mods-available/mpm_prefork.conf

   # prefork MPM
   # StartServers: number of server processes to start
   # MinSpareServers: minimum number of server processes which are kept spare
   # MaxSpareServers: maximum number of server processes which are kept spare
   # MaxRequestWorkers: maximum number of server processes allowed to start
   # MaxConnectionsPerChild: maximum number of requests a server process serves
   
   <IfModule mpm_prefork_module>
           StartServers              5
           MinSpareServers           5
           MaxSpareServers           10
           MaxRequestWorkers         150
           MaxConnectionsPerChild    0
   </IfModule>
   
   # vim: syntax=apache ts=4 sw=4 sts=4 sr noet

2. On Debian 10, the event module is enabled by default. Disable it, and enable the prefork module :

   sudo a2dismod mpm_event
   sudo a2enmod mpm_prefork
   

3. Restart Apache:

   sudo service apache2 restart
   

The Worker Module

The Worker Module is a hybrid Prefork, multi-threaded, multi-processor module. It’s similar to the Prefork Module, but each child is multi-threaded.

1. Open /etc/apache2/mods-available/mpm_worker.conf in your text editor and edit the values as needed. The following are the default values:

   File: /etc/apache2/mods-available/mpm_worker.conf

   <IfModule mpm_worker_module>
           StartServers             2
           MinSpareThreads          25
           MaxSpareThreads          75
           ThreadLimit              64
           ThreadsPerChild          25
           MaxRequestWorkers        150
           MaxConnectionsPerChild   0
   </IfModule>
   
   # vim: syntax=apache ts=4 sw=4 sts=4 sr noet

2. On Debian 10, the event module is enabled by default. Disable it, and enable the worker module :

   sudo a2dismod mpm_event
   sudo a2enmod mpm_worker
   

3. Restart Apache:

   sudo service apache2 restart
   

The Event Module

The Event Module is similar to the Worker Module except each thread has a dedicated listener so that threads are not locked in wait. As of Apache 2.4 the Event Module is considered stable, for versions before 2.4, use the Worker Module.

1. If you choose to keep the event module enabled, open /etc/apache2/mods-available/mpm_event.conf in your text editor and edit the values as needed. The following are the default values:

   File: /etc/apache2/mods-available/mpm_event.conf

   # event MPM
   # StartServers: initial number of server processes to start
   # MinSpareThreads: minimum number of worker threads which are kept spare
   # MaxSpareThreads: maximum number of worker threads which are kept spare
   # ThreadsPerChild: constant number of worker threads in each server process
   # MaxRequestWorkers: maximum number of worker threads
   # MaxConnectionsPerChild: maximum number of requests a server process serves
   <IfModule mpm_event_module>
           StartServers             2
           MinSpareThreads          25
           MaxSpareThreads          75
           ThreadLimit              64
           ThreadsPerChild          25
           MaxRequestWorkers        150
           MaxConnectionsPerChild   0
   </IfModule>
   
   # vim: syntax=apache ts=4 sw=4 sts=4 sr noet

2. Restart Apache:

   sudo service apache2 restart
   

Configure Virtual Hosting

Apache supports name-based virtual hosting, which allows you to host multiple domains on a single server with a single IP. Although there are different ways to set up virtual hosts, the method below is recommended.

1. Disable the default Apache virtual host:

   sudo a2dissite 000-default.conf
   

2. Create an example.com.conf file in /etc/apache2/sites-available with your text editor, replacing instances of example.com with your own domain URL in both the configuration file and in the file name:

   File: /etc/apache2/sites-available/example.com.conf

   1 2 3 4 5 6 7 8

   <VirtualHost *:80> ServerAdmin webmaster@example.com ServerName example.com ServerAlias www.example.com DocumentRoot /var/www/example.com/public_html/ ErrorLog /var/www/example.com/logs/error.log CustomLog /var/www/example.com/logs/access.log combined </VirtualHost>

   Repeat this process for any other domains you host.

   Note

   If you would like to enable Perl support, add the following lines above the closing </VirtualHost> tag:

   File: /etc/apache2/sites-available/example.com.conf

   1 2	Options ExecCGI AddHandler cgi-script .pl

3. Create directories for your websites and websites’ logs, replacing example.com with your own domain information:

   sudo mkdir -p /var/www/example.com/public_html
   sudo mkdir /var/www/example.com/logs
   

4. Create a simple page for your index.html.

   File: /var/www/example.com/public_html/index.html

   1 2 3 4 5 6 7 8 9

   <!DOCTYPE html> <html> <head> <title>Hello World</title> </head> <body> <h1>Hello World! This is my sample website with Apache on Debian!</h1> </body> </html>

5. Enable the site:

   sudo a2ensite example.com.conf
   

6. Restart Apache:

   sudo service apache2 restart
   

7. Visit your site by navigating to your domain name in the web browser.

Apache Mods and Scripting

Install Apache Modules

One of Apache’s strengths is its ability to be customized with modules. The default installation directory for Apache modules is the /etc/apache2/mods-available/ directory.

1. List available Apache modules:

   sudo apt-cache search libapache2*
   

2. Install any desired modules:

   sudo apt-get install [module-name]
   

3. All mods are located in the /etc/apache2/mods-avaiable directory. Edit the .conf file of any installed module if needed, then enable the module:

   sudo a2enmod [module-name]
   

   To disable a module that is currently enabled:

   a2dismod [module-name]
   

Optional: Install Support for Scripting

The following commands install Apache support for server-side scripting in Perl, Python, and PHP. Support for these languages is optional based on your server environment.

To install:

• Perl support:

  sudo apt-get install libapache2-mod-perl2
  

• Python support:

  sudo apt-get install libapache2-mod-python
  

• PHP support:

  sudo apt-get install php7.2 php-pear
  

Check Server Status

You can check your Apache web server status with the following command:

sudo systemctl status apache2

The output will look similar to the following:

● apache2.service - The Apache HTTP Server
   Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2020-03-02 18:41:24 UTC; 9s ago
     Docs: https://httpd.apache.org/docs/2.4/
 Main PID: 1543 (apache2)
    Tasks: 55 (limit: 1149)
   Memory: 12.8M
   CGroup: /system.slice/apache2.service
           ├─1543 /usr/sbin/apache2 -k start
           ├─1545 /usr/sbin/apache2 -k start
           └─1546 /usr/sbin/apache2 -k start

• From here you can see that the server is running successfully. However, if something isn’t working correctly, you can check the logs for errors. The logs locations are defined for each virtual host you set up in Configure Virtual Hosting.

• Typically they will be at /var/www/example.com/logs/error.log and /var/www/example.com/logs/access.log where example.com is your domain name.

Controlling Apache

You can control the server in the following ways.

1. Stopping the server when it’s running:

   sudo systemctl stop apache2
   

2. Start the server when it’s stopped:

   sudo systemctl start apache2
   

3. Stop and start the server when it’s running:

   sudo systemctl restart apache2
   

4. Reload the configurations while the server is running without stopping it:

   sudo systemctl reload apache2
   

5. You can disable Apache so that it stops and doesn’t restart again when rebooting the system:

   sudo systemctl disable apache2
   

6. To re-enable Apache if it’s been disabled. This will also enable it to restart when the system reboots:

   sudo systemctl enable apache2
   

Optional: Firewall

Depending on your firewall configuration, you may need to modify your settings to allow access to web ports. A popular firewall for Debian is UFW.

If you had UFW installed before you installed Apache, Apache will have registered with UFW during installation and provides some simple to use configurations.

1. To view these options, run the following command:

   sudo ufw app list
   

   Available applications:
   Apache
   Apache Full
   Apache Secure
   OpenSSH

2. To view what these different configurations do, run this command:

   sudo ufw app info 'Apache'
   

   Replace Apache with Apache Full or Apache Secure to see information about those applications. Below is a table summary.

   Profile	Title	Ports
   Apache	Web Server	80/tcp
   Apache Full	Web Server (HTTP,HTTPS)	80,443/tcp
   Apache Secure	Web Server (HTTPS)	443/tcp

3. To enable a profile use the following command:

   sudo ufw allow 'Apache'
   

   Rules updated
   Rules updated (v6)

4. Verify the rules are updated with the following:

   sudo ufw status
   

   Status: active
   
   To              Action      From
   --              -----       ----
   Apache          ALLOW       Anywhere
   Apache (v6)     ALLOW       Anywhere (v6)

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Apache HTTP Server Version 2.4 Documentation
• Apache Configuration