Cannot refresh from ubuntu-core 2.15.2 on raspberry pi "ubuntu core 16" image - snap-declaration for "snapweb": parsing assertion headers: expected 4 chars nesting prefix after multiline introduction "plugs:": " network:"

[Zygmunt Krynicki]

I was reinstalling my fleet of devices when I noticed stable images cannot update due to a store response for snapweb.

zyga@localhost:~$ snap --version
snap 2.15.2
snapd 2.15.2
series 16

zyga@localhost:~$ sudo snap refresh
error: cannot refresh []: cannot refresh snap-declaration for "snapweb": parsing assertion headers: expected 4 chars nesting prefix after multiline introduction "plugs:": " network:"

zyga@localhost:~$ sudo snap refresh ubuntu-core
error: cannot refresh "ubuntu-core": cannot refresh snap-declaration for "snapweb": parsing assertion headers: expected 4 chars nesting prefix after multiline introduction "plugs:": " network:"

zyga@localhost:~$ sudo snap remove snapweb
snapweb removed

zyga@localhost:~$ sudo snap refresh ubuntu-core
[/] Make snap "ubuntu-core" (1799) available to the system
Broadcast message from <email address hidden> (Sun 2018-11-11 18:50:50 UTC):

reboot scheduled to update the system - temporarily cancel with 'sudo shutdown -c'
The system is going down for reboot at Sun 2018-11-11 19:00:50 UTC!

63.40 MB / 63.57 MB [===================================>_] 99.73 % 946.61 KB/s

ubuntu-core (beta) 16-2 from 'canonical' upgraded

[Samuele Pedroni (pedronis)]

this is likely related to a configuration change in the store that stopped interpreting missing max-format query param as max-format=0 on assertions.ubuntu.com/v1/assertions/<type>/<primary-key> requests

[Samuele Pedroni (pedronis)]

To be clear we do want to keep the new behavior on the snapdevicegw own endpoints, the assertions.ubutnu.com behavior is stricly for backward compatibility but it's fairly confusing curl using

[Bret Barker (noise)]

pedronis, can you complete your comment above? appears to have been cutoff.

[Zygmunt Krynicki (zyga)]

I'm marking the store side of the bug as confirmed since this prevents anyone from using the images from http://cdimage.ubuntu.com/ubuntu-snappy/16.04/current/

zyga@core16:~$ sudo snap refresh
error: cannot refresh []: cannot refresh snap-declaration for "snapweb": parsing assertion headers: expected 4 chars nesting prefix after multiline introduction "plugs:": " network:"

[Maximiliano Bertacchini (maxiberta)]

Not reproducible with the current ubuntu core 16 image from http://cdimage.ubuntu.com/ubuntu-core/16/stable/current/ (dated on 2019-08-06).

maxiberta@localhost:~$ snap version
snap 2.39.3
snapd 2.39.3
series 16
kernel 4.4.0-157-generic

maxiberta@localhost:~$ snap list
Name Version Rev Tracking Publisher Notes
core 16-2.39.3 7270 stable canonical✓ core
pc 16.04-0.10 33 stable canonical✓ gadget
pc-kernel 4.4.0-157.185 258 stable canonical✓ kernel

maxiberta@localhost:~$ sudo snap refresh
Setup snap "core" (8268) security profiles
Broadcast message from <email address hidden> (Fri 2020-02-07 19:30:12 UTC):
reboot scheduled to update the system
The system is going down for reboot at Fri 2020-02-07 19:40:12 UTC!
snapd is about to reboot the system

[Maximiliano Bertacchini (maxiberta)]

Some archaeology:
- Snapd 2.27 switched from "assertions.ubuntu.com" to "api.snapcraft.io", released on Aug 10 2017 [1][2].
- The assertions service switched json by default around Jan 15 2018 (it was committed on that date, not exactly sure when deployed to production but should be close enough)[3].

[1] https://github.com/snapcore/snapd/releases?after=2.28
[2] https://github.com/snapcore/snapd/pull/3500
[3] https://code.launchpad.net/~pedronis/snap-assertions-service/simplified-snap-assert/+merge/335253

[Maximiliano Bertacchini (maxiberta)]

- Snapd 2.17 started sending "max-format" when retrieving assertions, released on Nov 2, 2016 [4].

[4] https://github.com/snapcore/snapd/blob/master/packaging/ubuntu-16.04/changelog#L6669

[Maximiliano Bertacchini (maxiberta)]

So, iiuc, defaulting to the old format on requests with no explicit "max-format" on "assertions.ubuntu.com" would fix the issue.

[Samuele Pedroni (pedronis)]

> So, iiuc, defaulting to the old format on requests with no explicit "max-format" on "assertions.ubuntu.com" would fix the issue.

yes, I think the fix would be to detect) if a request comes through the "old" assertions.ubuntu.com and in that case use max-format=0 if max-format is not set

[Maximiliano Bertacchini (maxiberta)]

> yes, I think the fix would be to detect) if a request comes through the "old" assertions.ubuntu.com and in that case use max-format=0 if max-format is not set

This fix has been implemented server-side in the Snap Store. No action needed from snapd, afaict.