UI shows loading screen for entire install while doing fully automated install

[Dan Bungert]

While testing build 20240422 of noble-desktop daily-live with a fully-automated install, I observed that the loading screen never moved on from "Preparing Ubuntu".

The install did complete successfully otherwise. During the install I observed that /meta/status was returning a RUNNING state.

[Dan Bungert (dbungert)]

A second install produced the same result. The first two installs used refresh-installer: {update: yes}.
A third install used refresh-installer: {update: no} and behave correctly.

Dennis observed the following:
> in subiquity-server-debug.log.3845 from your logs I see
> 2024-04-22 14:41:41,983 INFO root:38 start: subiquity/Meta/status_GET:
> which is not followed by a subiquity/Meta/status_GET: SUCCESS: 200 ...
> possibly what causes the broken state in the UI

[Dan Bungert (dbungert)]

I believe that Subiquity-side, on shutdown of the server process, the outstanding waiting API calls are returning null. This is outside the API contract of /meta/status, which claims to only return ApplicationStatus.

[Olivier Gayot (ogayot)]

> I believe that Subiquity-side, on shutdown of the server process, the outstanding waiting API calls are returning null. This is outside the API contract of /meta/status, which claims to only return ApplicationStatus.

This is not exactly what I observed. On shutdown, it seems that the server simply closes the connection without replying to the query:

+ curl --unix-socket .subiquity/socket 'http://a/meta/status?cur="WAITING"' -v
* Trying .subiquity/socket:0...
* Connected to a (.subiquity/socket) port 80
> GET /meta/status?cur="WAITING" HTTP/1.1
> Host: a
> User-Agent: curl/8.5.0
> Accept: */*
>
* Empty reply from server
* Closing connection
curl: (52) Empty reply from server

[Olivier Gayot (ogayot)]

I believe the "null" status is internal to ubuntu-desktop-provision and is set as the result of the stream calling onError when the socket gets closed:

https://github.com/canonical/ubuntu-desktop-provision/blob/9957a5b31a5f4cb4cd5e94ac893f6af06750f98b/packages/subiquity_client/lib/src/status_monitor.dart#L57

[Dennis Loose (dloose)]

Thanks Olivier, you're right - the UI's status monitor currently enters a 'null' state which it can't recover from when subiquity restarts. We should probably handle this more gracefully and attempt to re-connect to subiquity a certain number of times.

[Olivier Gayot (ogayot)]

I merged https://github.com/canonical/subiquity/pull/1996 ; which documents what happens when the server restarts. TBD if further change in Subiquity is needed.