Setting "Domain" dynamically when using Apache2::AuthCookie. Title says it all.I've tried $r->dir_config and even more obscure paths and suspect I can't see the forest for the trees. Any suggestions welcome :)

What did you try exactly and where (what file, context)?

If Apache2::AuthCookie with mod_perl: Apache2::PerlSections - write Apache configuration files in Perl

Then maybe

  $VirtualHost{"www.yourdomain.com"} = {
     DocumentRoot => "/tmp/docs",
     ErrorLog => "/dev/null",
     WhatEverSatisfy => "Any",
     WhatEverDomain  => ".yourdomain.com",
     Location => {
       "/" => {
         Allowoverride => 'All',
         Order => 'deny,allow',
         Deny  => 'from all',
         Allow => 'from foo.com',
       },
       "/protected" => {
            AuthType => 'Sample::Apache2::AuthCookieHandler',
            AuthName => 'WhatEver',
            ## might be "AuthenHandler"
            PerlAuthenHandler => "Sample::Apache2::AuthCookieHandler->
+authenticate",
            PerlAuthzHandler => "Sample::Apache2::AuthCookieHandler->a
+uthorize",
            require  => "valid-user",
       },
     },
  };
[download]

Maybe also idea to use prefix of "yourdomainAUC" for all those cookie auth vars

I guess a couple customized apache configs is better than trying to be all elegant and complicated. Thanks!