DA aliases and shared login

Shared logins just require that you set the cookie domain correctly. See the cookie domain section of the documentation for configuring settings.php (http://drupal.org/node/1096962).

The great module is all due to @agentrickard, I just help around the queue with the simple stuff when I can, and since your current question isn't simple enough for me to know the answer to I'll have to leave this for him.

You would need to wrap $cookie_domain in some logic similar to:

if (isset($_SERVER['HTTP_REQUEST'])) {
  if (substr_count($_SERVER['HTTP_REQUEST'], 'domain1.com') > 0) {
    $cookie_domain = '.domain1.com';
  }
  elseif (substr_count($_SERVER['HTTP_REQUEST'], 'domain2.com') > 0) {
    $cookie_domain = '.domain2.com';
  }
  // And so on. You might also be able to do regex matching.
}

This all goes in settings.php, before the DA include.

Hello guys !
I hope this issue match up with my problem !

on my localhost I created 2 domains with (wonderfull) Domain Access module :
domain1.dev
domain2.dev
I'd like when the users log in one of this 2 domains they're automatically log in the other one, is it possible ?

I tried #4, it doesn't work.
Then I tried this :
http://drupal.org/node/1348784
It seems corresponding what I want but it doesn't work, maybe I did it wrong ?

I put this in settings.php before the Domain Access include :

$cookie_domain = '.domain1.dev';
if (isset($_SERVER['HTTP_HOST']) && substr_count($_SERVER['HTTP_HOST'], 'domain2.dev') > 0) {
$cookie_domain = '.domain2.dev';
}

Please can you tell me what I'm doing wrong ?
Thanks for help and sorry for my bad english T__T

You can't do this because browser security won't let you store the same login cookie for two domains that don't share a top level.

e.g. if you had 'example.com' and 'one.example.com', you can share '.example.com'.

In your setup, the Drupal login cookie would get reset every time a user switched domains.

See https://drupal.org/node/1096944 and INSTALL.txt.