Apache configuration

The configuration of the Apache HTTP Server (Apache) can vary between OS distributions; see the documentation specific to your installation of Apache.


The following notes are applicable for CentOS/RHEL7, RHEL 8, and RHEL 9:

  • Swarm 2019.1 to 2020.1: these versions of Swarm used PHP packages from the SCL repositories for CentOS/RHEL 7. This was to provide access to more recent versions of PHP than are available as standard on CentOS/RHEL. This required the use of the httpd24-httpd package for Apache. These were all installed into /opt/rh

    Swarm 2020.2 and later: these versions of Swarm uses the Remi repository for CentOS/RHEL 7, RHEL 8, and RHEL 9. This provides PHP 7.4 installed in the standard file system structure. This means that the old httpd24-httpd version of Apache is no longer needed, and the standard system version of Apache is being used again.

    The SCL Apache site configuration file was installed at this location for Swarm 2019.1 to 2020.1:


    If this exists when Swarm is upgraded to 2020.2 and later, this file is copied to /etc/httpd/conf.d/perforce-swarm-site.conf if there is no file at the destination. It is also re-written to change references from /var/log/httpd24 to /var/log/httpd

    If a site configuration file for Swarm already exists in /etc/httpd, the copy and re-write is not performed.

    After upgrade, httpd24-httpd is disabled.

  • To avoid seeing the Apache HTTP server Linux test page when you start the Apache server, comment out the content of the welcome.conf file located in the /etc/httpd/conf.d/ directory.

  • To avoid loading the Apache HTTP server example configuration instead of the Swarm configuration when the Apache server starts, rename the autoindex.conf file located in the /etc/httpd/conf.d/ directory to z-autoindex.conf or similar. This is required because Apache runs the first conf file it finds in the /etc/httpd/conf.d/ directory (alphabetical order) and that must be the perforce-swarm-site.conf file.

  1. Locate your system's Apache configuration.

    Common configuration directories include:

    • /etc/httpd/conf/
    • /etc/apache2/
    • /usr/local/apache2/conf/
    • /Applications/XAMPP/etc/

    Within the configuration path, the main Apache configuration file is usually named one of the following:

    • httpd.conf
    • apache2.conf

    A longer discussion on the possible locations and names of Apache configuration files is available here : https://cwiki.apache.org/confluence/display/httpd/DistrosDefaultLayout

  2. Set up an Apache virtual host (vhost) for your installation.

    If your Apache configuration directory contains the directories sites-available and sites-enabled:

    1. Copy the appropriate virtual host definition below into the file sites-available/swarm.
    2. Enable the Swarm virtual host definition.

      sudo a2ensite swarm

    Otherwise, copy the virtual host definition below into the bottom of the main Apache configuration file, httpd.conf or apache2.conf.

    Virtual host definition example for Apache 2.4:

    <VirtualHost *:80>
        ServerName myswarm.host
        AllowEncodedSlashes NoDecode
        ServerAlias myswarm
        ErrorLog "/path/to/apache/logs/myswarm.error_log"
        CustomLog "/path/to/apache/logs/myswarm.access_log" common
        DocumentRoot "/path/to/swarm/public"
        <Directory "/path/to/swarm/public">
            AllowOverride All
            Require all granted


    See Apache's virtual host documentation for details: https://httpd.apache.org/docs/2.4/vhosts/

  3. Customize the virtual host definition.
    1. Replace myswarm.host with the hostname for Swarm on your network. This may require adjusting the DNS configuration on your network.
    2. Replace myswarm with the name of the subdomain hosting Swarm. Many administrators choose swarm.


      The string myswarm in the log file paths: this should match the subdomain name and prefix for the log files, to help coordinate the active host with the log files for that host. Doing this is particularly useful when your Apache server hosts multiple instances of Swarm.

    3. Replace /path/to/apache/logs with the path where your Apache stores its log files. Apache's log files are typically named access_log and error_log.
    4. Replace /path/to/swarm with the path to the Swarm directory.
  4. Verify that the correct Apache modules are enabled.

    • To query whether the PHP and Rewrite modules are active, use the apachectl utility to list all of the active modules (this may be named apache2ctl on your system):

      apachectl -t -D DUMP_MODULES

    • Simply look for php7_module and rewrite_module in the output. If you see them, skip ahead to step 5.
    • If the Apache utility a2enmod is installed, use it to enable the PHP and Rewrite modules:

      sudo a2enmod php7 rewrite

    • Without the a2enmod utility, edit the Apache configuration file by hand. Locate your Apache configuration file for modules and either uncomment or add the following lines:

      LoadModule  php7_module     libexec/apache2/libphp7.so
      LoadModule rewrite_module libexec/apache2/mod_rewrite.so
    • Note that your Apache installation may have different paths for the location of its modules (the .so files).
  5. Restart your web server.

    • To ensure that the Apache configuration changes you made become active, restart the web server.

      sudo apachectl restart

    • Query Apache's active virtual hosts and modules to confirm your changes are in effect:

      apachectl -t -D DUMP_VHOSTS
      apachectl -t -D DUMP_MODULES

    Apache must be configured to use the prefork MPMClosed Multi-Processing Module, a component of the Apache web server that is responsible for binding to network ports, accepting requests, and dispatch operations to handle the request. because P4PHP does not support threaded operation.

    The prefork MPM is the default for Linux Apache installations, so you may not have to do anything.

    For more information on Apache MPMs and configuration, see: https://httpd.apache.org/docs/2.4/mpm.html

  6. Configure PHP, see PHP configuration.