How to use a RELATIVE path with AuthUserFile in htaccess?

It is not possible to use relative paths for AuthUserFile:

File-path is the path to the user file. If it is not absolute (i.e., if it doesn’t begin with a slash), it is treated as relative to the ServerRoot.

You have to accept and work around that limitation.

We’re using IfDefine together with an apache2 command line parameter:

.htaccess (suitable for both development and live systems):

<IfDefine !development>
  AuthType Basic
  AuthName "Say the secret word"
  AuthUserFile /var/www/hostname/.htpasswd
  Require valid-user
</IfDefine>

Development server configuration (Debian)

Append the following to /etc/apache2/envvars:

export APACHE_ARGUMENTS=-Ddevelopment

Restart your apache afterwards and you’ll get a password prompt only when you’re not on the development server.

You can of course add another IfDefine for the development server, just copy the block and remove the !.