How to get system environment variables into PHP while running CLI & Apache2Handler?

Original reply in 2014

I had exactly the same problem. To solve it, I just sourced /etc/environment inside /etc/apache2/envvars.

The content of /etc/environment:

export MY_PROJECT_PATH=/var/www/my-project
export MY_PROJECT_ENV=production
export MY_PROJECT_MAIL=support@my-project.com

The content of /etc/apache2/envvars:

# Load all the system environment variables.
. /etc/environment

Now, I’m able to use these variables in the Apache Virtual Host config files and in PHP.

Here’s an example of an Apache virtual host:

<VirtualHost *:80>
  ServerName my-project.com
  ServerAlias www.my-project.com
  ServerAdmin ${MY_PROJECT_MAIL}
  UseCanonicalName On

  DocumentRoot ${MY_PROJECT_PATH}/www

  # Error log.
  ErrorLog ${APACHE_LOG_DIR}/my-project.com_error.log
  LogLevel warn

  # Access log.
  <IfModule log_config_module>
    LogFormat "%h %l %u %t \"%m %>U%q\" %>s %b %D" clean_url_log_format
    CustomLog ${APACHE_LOG_DIR}/my-project.com_access.log clean_url_log_format
  </IfModule>

  # DocumentRoot directory
  <Directory ${MY_PROJECT_PATH}/www>
    # Disable .htaccess rules completely, for better performance.
    AllowOverride None
    Options FollowSymLinks Includes
    Order deny,allow
    Allow from All

    Include ${MY_PROJECT_PATH}/config/apache/inc.mime-types.conf
    Include ${MY_PROJECT_PATH}/config/apache/inc.cache-control.conf

    # Rewrite rules.
    <IfModule mod_rewrite.c>
      RewriteEngine on
      RewriteBase /

      # Include all the common rewrite rules (for http and https).
      Include ${MY_PROJECT_PATH}/config/apache/inc.rewriterules-shared.conf
    </IfModule>
  </Directory>
</VirtualHost>

And this is an example of how to access them with PHP:

<?php
header('Content-Type: text/plain; charset=utf-8');
print getenv('MY_PROJECT_PATH') . "\n" .
      getenv('MY_PROJECT_ENV') . "\n" .
      getenv('MY_PROJECT_MAIL') . "\n";
?>

Update from 2020

As mentioned by several of you, this method is rather old and not secure as we don’t want the web server to know all about
the other environment variables and let them be accessible by attackers.

My answer is very old and clearly not valid any more!

The main idea was to have a single place to define some project constants and to have them available at several places (bash scripts, Apache or Nginx conf, PHP scripts). You could have a project file
containing these vars and only source this one in
/etc/apache2/envvars and /etc/environment.

Since a few years, I use Ansible to deploy my projects. This way, I can define some constants or variables and inject them into multiple configuration files. I also have the flexibility to override them
and have variations of them if I deploy to a cluster of servers.