Integration of different resources

Question

Drupal

What is.
There is one corporate business card site on Drupal 7 (important) version, which will be actively used and filled.
There is a tracker on redmine that is actively used.
There is mail and documents on Google Apps for domains, which are no less actively used.

What is the problem.
On each resource, each user must log in, remember their logins and passwords, etc. Inconvenient, in a word.

What would you like.
I would like to make user integration and transparent authentication at least on Drupal with redmine. Ideally, with Google accounts.

Has anyone faced a similar issue? Is it possible? Can you provide a way to solve this problem?

Answer 1

None of the above, except for CAS, will help.

Answer 2

For druapl 6 there was a rudimentary integration module with Redmine. You understand, under 7 saw and saw.
For authentication, too, you can probably find something equally imperfect.

Answer 3

Google definitely has OpenID.
You need to dig in the direction of OpenID, it seems that it is in both Drupal and Redmine.

Answer 4

Or to dig towards LDAP.

Answer 5

A similar question has already been asked here , and they came to a consensus.