Can't get snap gui apps (notepadqq and firefox) to run in LXD/LXC container

[Bill Wood]

When starting notepadqq or firefox I get ln errors such as:
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Documents': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Desktop': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Downloads': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Music': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Pictures': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Videos': No such file or directory
ln: failed to create symbolic link '/home/ubuntu/snap/notepadqq/841/snap/notepadqq/841/Templates': No such file or directory

Then the gui window does not display but the app keeps running, eventually getting this error:
QXcbConnection: Could not connect to display :0
Aborted (core dumped)

x11 apps (such as firefox) work fine if installed with apt.

The host is running Ubuntu 18.04 and so is the container.

dmesg shows this error for notepadqq:

[349363.925230] audit: type=1107 audit(1527123518.868:1456): pid=516 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_signal" bus="system" path="/org/freedesktop/NetworkManager/ActiveConnection/7" interface="org.freedesktop.NetworkManager.Connection.Active" member="PropertiesChanged" name=":1.10" mask="receive" pid=25488 label="snap.notepadqq.notepadqq" peer_pid=545 peer_label="unconfined"

[Zygmunt Krynicki (zyga)]

NOTE: the apparmor denial is not relate dto the problem.

I don't think this is something strictly related to snapd. If anything I suspect that LXD needs to support this use case and extend its own sandbox accordingly. I'm adding a lxd task to track this.

[Zygmunt Krynicki (zyga)]

Hmm, LXD is using github for bug tracking. Not sure what to do.

[Zygmunt Krynicki (zyga)]

I'm marking this bug as invalid. I'll let LXD developers know to have a look and mirror this bug on their side.

[Stéphane Graber (stgraber)]

How did you configure your container to talk to X11 in the first place?

The error suggests that the X11 abstract Unix socket isn't available in your container.