Runtime config apache

Using custom php.ini files is pretty straighforward for CGI/FastCGI based PHP installations but it isn't feasible when running PHP as Apache module (mod_php) because the whole server runs a single instance of the PHP interpreter.

My advice:

• Set from PHP itself as many settings as you can:

  ini_set('memory_limit', '16M');
  date_default_timezone_set('Europe/Madrid')
  ...

  In other words, directives that can be changed at runtime.
• Set the rest of stuff from per-directory Apache setting files (aka .htaccess):

  php_flag short_open_tag off
  php_value post_max_size 50M
  php_value upload_max_filesize 50M

  i.e., settings that need to be defined before the script starts running

Please have a look at the Runtime Configuration for further details.

Sometimes, you'll actually need different settings in development and production. There're endless ways to solve that with PHP code (from creating a boolean constant from the $_SERVER['HTTP_HOST'] variable to just having a config.php file with different values) but it's trickier with .htaccess. I normally use the <IfDefine> directive:

<IfDefine DEV-BOX>
    #
    # Local server directives
    #
    SetEnv DEVELOPMENT "1"

    php_flag display_startup_errors on
    php_flag display_errors on
    php_flag log_errors off
    #php_value error_log ...
</IfDefine>
<IfDefine !DEV-BOX>
    #
    # Internet server directives
    #
    php_flag display_startup_errors off
    php_flag display_errors off
    php_flag log_errors on
    php_value error_log "/home/foo/log/php-error.log"
</IfDefine>

... where DEV-BOX is a string I pass to the local Apache command-line:

C:\Apache24\bin\httpd.exe -D DEV-BOX

If you run Apache as service, the -D DEV-BOX bit can be added in the Windows registry, e.g.:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Apache2.4\Parameters\ConfigArgs