Snap with ALSA lib does not work if run as daemon

[guy]

I got my snap working and now I need it to run as daemon (daemon: simple) in the background.
Unfortunately my snap use ALSA lib which cannot run with super user permissions https://forum.snapcraft.io/t/reusable-alsa-lib-part/3556/33

"With at least Ubuntu, the pulseaudio system is started per user session at login. This requires that the session be a desktop (gui) session. The pulseaudio system is restricted from being accessed by other users, including root, while it runs in a user session. What this means is that you cannot use the pulseaudio system from a daemon or system service or anything run through sudo."

Error:

  ALSA lib control.c:1373:(snd_ctl_open_noupdate) Invalid CTL hw:0
  ALSA lib control.c:1373:(snd_ctl_open_noupdate) Invalid CTL hw:1
  No protocol specified
  xcb_connection_has_error() returned true
  ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM sysdefault
  No protocol specified
  xcb_connection_has_error() returned true
  ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM sysdefault
  Fail to open PortAudio stream, error message is Device unavailable.

I am opening this bug because this is holding me back from continuing my startup and I need to stay notify if anything changes.

[Samuele Pedroni (pedronis)]

* we are implementing user daemon services

* there is a way for snap services to switch to a different user than root/drop privileges:

    https://forum.snapcraft.io/t/system-usernames/13386

[guy (guyluz11)]

I have created side project to test it.
While using the daemon services with
system-usernames:
  snap_daemon: shared
I still can't use alsa inside the sanp.

This is a link to the project on github if it more convenient for you https://github.com/guyluz11/Alsa-snap-not-working .
The .c file that I run is located in Alsa-snap-not-working/Again/scripts/cScripts/snowboy/examples/C/demo.c

I have also created question in the forum, there you can also see my .yaml file: https://forum.snapcraft.io/t/running-alsa-inside-daemon-snap/18850