layout lost after snapd refresh with long running content plugging snap

[Jamie Strandboge]

I have a (private, since it is not ready for consumption) snap that I use personally:

https://git.launchpad.net/~jdstrand/+git/hamster-jdstrand/tree/

It uses a layout:

  layout:
    /usr/share/hamster-applet:
      bind: $SNAP/usr/share/hamster-applet

and plugs gtk2 content:

  plugs:
    gtk-2-engines:
      interface: content
      target: $SNAP/lib/gtk-2.0
      default-provider: gtk2-common-themes
    gtk-2-themes:
      interface: content
      target: $SNAP/data-dir/themes
      default-provider: gtk2-common-themes
    icon-themes:
      interface: content
      target: $SNAP/data-dir/icons
      default-provider: gtk-common-themes
    sound-themes:
      interface: content
      target: $SNAP/data-dir/icons
      default-provider: gtk-common-themes

(note, I've since adjusted the snap to not use a layout to avoid this bug, but the snap in the wget uses the layout).

If I install the snap and run its 'indicator' (ie, a long running process) and then perform a snap refresh of the snapd snap, then the layout is lost. Steps to reproduce:

In a focal desktop VM:

$ snap info snapd # verify using stable
...
tracking: latest/stable
refresh-date: today at 09:29 CDT
channels:
  latest/stable: 2.45.2 2020-07-15 (8542) 31MB -
...

$ snap version
snap 2.45.2
snapd 2.45.2
series 16
ubuntu 20.04
kernel 5.4.0-37-generic

$ sudo apt-get install gconf2 # required for the snap to run

$ wget https://people.canonical.com/~jamie/zyga/hamster-jdstrand_4_amd64.snap

$ sudo snap install --devmode --dangerous ./hamster-jdstrand*snap

$ hamster-jdstrand.indicator
<indicator should now be running with this not returning>
<use indicator to 'Show Overview'. It should work>

In another terminal:

$ sudo snap refresh snapd --edge
$ snap version
snap 2.45.2+git2048.gb2fd998
snapd 2.45.2+git2048.gb2fd998
series 16
ubuntu 20.04
kernel 5.4.0-37-generic

Now go to indicator and do 'Show Overview' and it will fail with with (as seen in the first terminal):

/snap/hamster-jdstrand/x1/usr/lib/python2.7/dist-packages/hamster/configuration.py:156: GtkWarning: IA__gtk_accel_label_set_accel_closure: assertion 'gtk_accel_group_from_accel_closure (accel_closure) != NULL' failed
  ui.add_from_file(os.path.join(runtime.data_dir, name))
Traceback (most recent call last):
  File "/snap/hamster-jdstrand/x1/bin/hamster-indicator", line 212, in on_overview_show_activated
    dialogs.overview.show(self.indicator)
  File "/snap/hamster-jdstrand/x1/usr/lib/python2.7/dist-packages/hamster/configuration.py", line 106, in show
    dialog = self.get_dialog_class()(parent, **kwargs)
  File "/snap/hamster-jdstrand/x1/usr/lib/python2.7/dist-packages/hamster/overview.py", line 50, in __init__
    self._gui = load_ui_file("overview.ui")
  File "/snap/hamster-jdstrand/x1/usr/lib/python2.7/dist-packages/hamster/configuration.py", line 156, in load_ui_file
    ui.add_from_file(os.path.join(runtime.data_dir, name))
glib.GError: Failed to open file '/usr/share/hamster-applet/overview.ui': No such file or directory

Note, /usr/share/hamster-applet/overview.ui is from the layout as specified in the snap.

[Jamie Strandboge (jdstrand)]

Tentatively assigning to zyga since we discussed this on IRC. Please adjust as necessary.

[Zygmunt Krynicki (zyga)]

I tried reproducing but https://github.com/snapcore/snapd/compare/master...zyga:fix/lp-1888305?expand=1 was unsuccessful.

I have some more ideas to try today.