[arch-general] Env variable of user unit of ssh-agent not set

[eNV25]

> https://wiki.archlinux.org/title/SSH_keys#Start_ssh-agent_with_systemd_user
>
> It seems that SSH_AUTH_SOCK does not get set although it is in the user unit
> file.
>
> $ systemctl --user status ssh-agent.service
> ● ssh-agent.service - SSH key agent
>      Loaded: loaded (/home/rd/.config/systemd/user/ssh-agent.service; enabled;
> vendor preset: enabled)
>      Active: active (running) since Fri 2022-01-21 21:14:16 CET; 7min ago
>    Main PID: 574 (ssh-agent)
>       Tasks: 1 (limit: 9331)
>      Memory: 920.0K
>         CPU: 9ms
>      CGroup: /user.slice/user-2809.slice/user at 2809.service/app.slice/ssh-
> agent.service
>              └─574 /usr/bin/ssh-agent -D -a /run/user/2809/ssh-agent.socket
>
> Jan 21 21:14:16 n3150 ssh-agent[574]: SSH_AUTH_SOCK=/run/user/2809/ssh-
> agent.socket; export SSH_AUTH_SOCK;
> Jan 21 21:14:16 n3150 ssh-agent[574]: echo Agent pid 574;
> Jan 21 21:14:16 n3150 systemd[564]: Started SSH key agent.
>  $ cat .config/systemd/user/ssh-agent.service
> [Unit]
> Description=SSH key agent
>
> [Service]
> Type=simple
> Environment=SSH_AUTH_SOCK=%t/ssh-agent.socket
> # DISPLAY required for ssh-askpass to work
> Environment=DISPLAY=:0
> ExecStart=/usr/bin/ssh-agent -D -a $SSH_AUTH_SOCK
>
> [Install]
> WantedBy=default.target
>  $ ssh-add
> Could not open a connection to your authentication agent.
>  $ echo $SSH_AUTH_SOCK
>
>  $
>
> Can anybody tell what I am missing?
>
> Any hint or advice is welcome.
>

I think you need to add the variable in your shell's rc and make it
match the one in the service.

I have `export SSH_AUTH_SOCK="${XDG_RUNTIME_DIR:-/run/user/$UID}/ssh-agent.socket"`
in my ~/.zshrc