Manual:Configuration for developers

Configuration using (recommended)
Extensions that are should set up configuration variables as described in this section. if it's not the full extension name (e.g. is an abbreviation) then you should make sure it doesn't collide with any existing extension.

In :

In PHP, whenever you want your configuration values:

Configuration using globals
If you can, use the  file for configuration (see above). If you can't, use this snippet (only works with  prefixed variables):