Systemd user services

[Suvayu Ali]

Hi,

I wanted to run systemd user services, in linger mode, meaning they run
as a regular user and hang around without an active session.  This
worked nicely for the default target.  When I changed to a different
target however, the systemd user is not working anymore.  Any thoughts?

This is what I did step by step:
- Enable linger mode and reboot:
  # loginctl enable-linger user
- Now from a console login when I do:
  $ systemctl --user status
  I see systemd user service is running.
- I add a service like this:
  $ systemctl --user enable emacs
  $ systemctl --user start emacs
  Looking at the status now, I see emacs is running as expected.

This was just a test, I actually want to run mpd, but I was not getting
any sound without a graphical session, so temporarily I switched to a
graphical target with:
# systemctl isolate graphical.target # my default is runlevel3

IIUC, when I do this all services get restarted.  So I wasn't surprised
when there was not running emacs (checked with pgrep).  I was surprised
however to see I cannot query the user session anymore.

$ systemctl --user enable emacs.service
Failed to get D-Bus connection: No such file or directory

It is even more surprising since the systemd user service is still running!

$ ps -uf -p 14301
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
lightdm  14301  0.0  0.1  45004  4864 ?        Ss   10:18   0:00 /usr/lib/systemd/systemd --user

What is wrong?  Am I mistaken somewhere, or is this a bug?

Thanks for any thoughts.