tramp and ssh-agent / ssh-add

[Roland Winkler]

I've discussed the following with Michael Albinus on help-gnu-emacs.

The starting point was that I like to run remote emacs sessions as a
subprocess of ssh-agent. When using tramp for file transfer, I need
then ssh-add. The general question is: what is the best way to
communicate from within emacs with the agent?

Right now, I am using a home-made solution that uses a defadvice for
tramp-open-connection-rsh, a function from tramp 2.0, but not
available anymore in tramp 2.1. A hook would be a cleaner
alternative, but again it appears rather limited. Michael pointed
out that not only there is also the gpg agent, but Gnome and KDE
have keyring managers, too, and it might be useful to have a general
interface that allowed one to communicate from within emacs with
these agents. (Personally, I do not know anything about Gnome and
KDE.) Then tramp could use this interface to call ssh-add when
needed, and other packages could use it in a similar way.

I'd greatly prefer such an approach over caching passwords.
(Currently, tramp uses password.el for this which comes from Gnus.)

What do you think?

Roland