[Bug]: signal-desktop fails to start, when gnome-3-28-1804 is removed (which can be removed without warning)

[joergsteffens]

What happened?

I removed snap gnome-3-28-1804, as I though, I don't need it anymore.
After I while, I detected that the signal-desktop snap does not work anymore.
On command line I receive following output:

$ signal-desktop 
ERROR: not connected to the gnome-3-28-1804 content interface.

While it is understandable that signal-desktop needs gnome-3-28-1804, I wonder why I can remove this snap without getting a dependency warning. Are there dependencies information missing in the signal-desktop snap.

I'm still using signal-desktop 401 because of #79

Steps to reproduce:

$ signal-desktop
... starts successfully
$ sudo snap remove gnome-3-28-1804
gnome-3-28-1804 removed
$ signal-desktop 
ERROR: not connected to the gnome-3-28-1804 content interface.
$ snap refresh --revision=401 signal-desktop
... did also silently install gnome-3-28-1804
$ signal-desktop 
... again starts successfully

I think, instead of snap refresh signal-desktop I initially re-installed gnome-3-28-1804, but still, signal-desktop has not been startable. However, in my latest tests also reinstalling gnome-3-28-1804 did solve the issue.

Maybe relevant, that I've multiple versions of gnome installed:

snap list | grep gnome
gnome-3-28-1804      3.28.0-19-g98f9e67.98f9e67  161    latest/stable  canonical**             -
gnome-3-38-2004      0+git.6f39565               119    latest/stable  canonical**             -
gnome-42-2204        0+git.c271a86               44     latest/stable  canonical**             -

What should have happened?

sudo snap remove gnome-3-28-1804 should tell me, that signal-desktop has a dependency to it. Or at least, trying to start signal-desktop via GUI should give a graphical error message.

Output of snap info $snap_name

# snap info signal-desktop 
name:      signal-desktop
summary:   Private messaging from your desktop.
publisher: Snapcrafters
store-url: https://snapcraft.io/signal-desktop
contact:   https://github.com/snapcrafters/signal-desktop/issues
license:   AGPL-3.0-only
description: |
  Private messaging from your desktop.
  
  To use the Signal desktop app, Signal must first be installed on your phone.
  
  **Are you having issues?**
  
  Let us know by creating a new issue here: https://github.com/snapcrafters/signal-desktop/issues
  
  **Authors**
  
  This snap is maintained by the Snapcrafters community, and is not necessarily endorsed or
  officially maintained by the upstream developers.
commands:
  - signal-desktop
snap-id:      r4LxMVp7zWramXsJQAKdamxy6TAWlaDD
tracking:     latest/stable
refresh-date: today at 18:20 CET
channels:
  latest/stable:    6.0.0  2022-12-01 (406) 196MB -
  latest/candidate: ^                             
  latest/beta:      5.62.0 2022-11-24 (400) 192MB -
  latest/edge:      6.0.0  2022-11-30 (406) 196MB -
installed:          5.63.0            (401) 196MB -

Output of snap connections $snap_name

Working:
# snap connections signal-desktop
Interface                 Plug                            Slot                             Notes
audio-playback            signal-desktop:audio-playback   :audio-playback                  -
audio-record              signal-desktop:audio-record     :audio-record                    -
browser-support           signal-desktop:browser-support  :browser-support                 -
camera                    signal-desktop:camera           :camera                          -
content[gnome-3-28-1804]  signal-desktop:gnome-3-28-1804  gnome-3-28-1804:gnome-3-28-1804  -
content[gtk-3-themes]     signal-desktop:gtk-3-themes     gtk-common-themes:gtk-3-themes   -
content[icon-themes]      signal-desktop:icon-themes      gtk-common-themes:icon-themes    -
content[sound-themes]     signal-desktop:sound-themes     gtk-common-themes:sound-themes   -
desktop                   signal-desktop:desktop          :desktop                         -
desktop-legacy            signal-desktop:desktop-legacy   :desktop-legacy                  -
gsettings                 signal-desktop:gsettings        :gsettings                       -
home                      signal-desktop:home             :home                            -
network                   signal-desktop:network          :network                         -
opengl                    signal-desktop:opengl           :opengl                          -
removable-media           signal-desktop:removable-media  -                                -
unity7                    signal-desktop:unity7           :unity7                          -
wayland                   signal-desktop:wayland          :wayland                         -
x11                       signal-desktop:x11              :x11                             -

Not working:
# snap connections signal-desktop
Interface              Plug                            Slot                            Notes
audio-playback         signal-desktop:audio-playback   :audio-playback                 -
audio-record           signal-desktop:audio-record     :audio-record                   -
browser-support        signal-desktop:browser-support  :browser-support                -
camera                 signal-desktop:camera           :camera                         -
content                signal-desktop:gnome-3-28-1804  -                               -
content[gtk-3-themes]  signal-desktop:gtk-3-themes     gtk-common-themes:gtk-3-themes  -
content[icon-themes]   signal-desktop:icon-themes      gtk-common-themes:icon-themes   -
content[sound-themes]  signal-desktop:sound-themes     gtk-common-themes:sound-themes  -
desktop                signal-desktop:desktop          :desktop                        -
desktop-legacy         signal-desktop:desktop-legacy   :desktop-legacy                 -
gsettings              signal-desktop:gsettings        :gsettings                      -
home                   signal-desktop:home             :home                           -
network                signal-desktop:network          :network                        -
opengl                 signal-desktop:opengl           :opengl                         -
removable-media        signal-desktop:removable-media  -                               -
unity7                 signal-desktop:unity7           :unity7                         -
wayland                signal-desktop:wayland          :wayland                        -
x11                    signal-desktop:x11              :x11                            -

Output of snap version

# snap version
snap    2.57.6
snapd   2.57.6
series  16
ubuntu  20.04
kernel  5.4.0-126-generic

Relevant log output

No response

Teminal output of app

$ signal-desktop 
ERROR: not connected to the gnome-3-28-1804 content interface.

[lucyllewy]

This is not anything we can control from here. It is up to snapd to orchestrate this. You might want to report this on forum.snapcraft.io in the snapd category/tag. I suspect that it will be a case of "working as designed". As this is not something we have influence over with the capabilities provided by snapcraft and snapd I'm going to close this issue for now. I appreciate that isn't too helpful to resolve this issue tho.