Snapcraft is stuck on "launching instance..." indefinitely

[Matthew Jakeman]

When I run the "snapcraft" command, it gets stuck on "Launching instance..." indefinitely. I waited upwards of an hour before terminating the command.

If relevant (possibly due to the hardware I'm using - M1 Macbook), I am running this on the arm64 architecture. I can reproduce this on:
 - Fedora Workstation 37 (arm64)
 - Asahi Linux (arm64)

This means I am unable to build or test any snap file.

[Callahan Kovacs (mr-cal)]

Interesting. We have some outstanding work to time out early and provide logs when snapcraft gets stuck launching an instance (https://github.com/canonical/craft-providers/issues/146).

The hardware part is interesting. This could be a LXD or Multipass issue on this hardware. If you're building a core22 snap, I'd like to see the output of `snapcraft --verbosity=trace`.

I also wonder if you have the same behavior with Multipass and LXD. You can change between the two with `snap set snapcraft provider=lxd` (or multipass).

[Matthew Jakeman (mjakeman)]

When running with Multipass, I get an error that an image matching "22.04" cannot be found. LXD seems seems to loop on "[...] getent hosts snapcraft.io" endlessly. I'll attach logs for both attempts.

For reference, the snap I am trying to build is: `https://github.com/mjakeman/extension-manager/pull/314/files` with arm64 added as an additional supported architecture.

[Farshid Tavakolizadeh (farshidtz)]

I often face this issue on a Raspberry Pi 4 (Ubuntu Server 22.04):

2023-02-27 14:55:41.908 Executing in container: lxc --project snapcraft exec local:snapcraft-matter-pi-gpio-commander-on-arm64-for-arm64-151427 -- env PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin SNAPCRAFT_MANAGED_MODE=1 getent hosts snapcraft.io
2023-02-27 14:55:42.593 Executing in container: lxc --project snapcraft exec local:snapcraft-matter-pi-gpio-commander-on-arm64-for-arm64-151427 -- env PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin SNAPCRAFT_MANAGED_MODE=1 getent hosts snapcraft.io

It appears to be a re-occurring domain resolution issue, unrelated to snapcraft.

$ host snapcraft.io
Host snapcraft.io not found: 2(SERVFAIL)
$ host google.com
Host google.com not found: 2(SERVFAIL)

Changing the DNS addresses or rebooting the device solves it.

[Claudio André (claudioandre.br)]

The tip that the problem is related to network access saved my day. In my case, the firewall was preventing LXD from working properly. Disabling the firewall (or fixing the rules) does the trick.

Yesterday:
`
[UFW BLOCK] IN=lxdbr0 OUT= PHYSIN=vethd728cd65 MAC=00:16:3e:83:1c:fd:00:16:3e:b4:de:c7:86:dd SRC=fe80:0000:0000:0000:0216:3eff:feb4:dec7 DST=fe80:0000:0000:0000:0216:3eff:fe83:1cfd LEN=78 TC=0 HOPLIMIT=64 FLOWLBL=1016275 PROTO=UDP SPT=42222 DPT=53 LEN=38
`
Now:
`
UFW BLOCK] IN=lxdbr0 OUT= PHYSIN=vethe4c2b3ac MAC=00:16:3e:83:1c:fd:00:16:3e:b4:de:c7:86:dd SRC=fe80:0000:0000:0000:0216:3eff:feb4:dec7 DST=fe80:0000:0000:0000:0216:3eff:fe83:1cfd LEN=78 TC=0 HOPLIMIT=64 FLOWLBL=759663 PROTO=UDP SPT=59514 DPT=53 LEN=38
`

Could you guys add an alert the end user to make our life easier?

- I am on Ubuntu 22, snapping for core22, snapcraft via snap.

[Callahan Kovacs (mr-cal)]

Yeah, thanks for the feedback!

We now have two improvements to add:
1. Add timeouts to network calls (https://github.com/canonical/craft-providers/issues/146)
2. Check for the presence of Docker modifying iptables on the host (https://github.com/canonical/craft-providers/issues/172)

Both of these will include better logging and/or documentation to make your life easier.

[Callahan Kovacs (mr-cal)]

@mjakeman, your issue with Snapcraft+Multipass not working on arm64 hardware sounds like this bug (https://bugs.launchpad.net/snapcraft/+bug/2012074). Sorry for suggesting you try something that doesn't work!