Support GitLab bug watches

[Barry Warsaw]

This matrix describes the supported remote bug trackers: https://help.launchpad.net/Bugs/RemoteTrackerCoverage

which is great! This is a wishlist item for remote tracking gitlab.com bugs. It might make sense to support general GitLab bug tracking as a generic feature (since GitLab CE is open source and making its way into Debian), and gitlab.com (a hosted GitLab EE) as a specific feature.

[Mario Limonciello (superm1)]

So recently GNOME migrated over to Gitlab. I'm finding as a result bug tracking from GNOME's bug tracker stopped working.

Here's an example issue:
https://bugs.launchpad.net/gnome-software/+bug/1719797
which is supposed to track https://gitlab.gnome.org/GNOME/gnome-software/issues/253

[Jeremy Bícha (jbicha)]

See also LP: #1745210

[Colin Watson (cjwatson)]

Driving the GitLab issues API itself will be pretty easy based on the GitHub implementation; there are differences in details, but if anything it's mostly slightly simpler.

However, one tricky bit here will be that GitLab's issues API absolutely requires authentication. Now, we do authenticate to GitHub as well, but there's only one instance there so we can afford for that to be configured manually. Not so much with the many GitLab instances out there.

I think what we'll probably need to do as part of this is:

 * extend the BugTracker table with somewhere to store credentials
 * add (probably) an OAuth flow to the relevant GitLab instance as part of setting up a bug tracker, so we'd end up with the external bug tracker instance set up to use a particular person's credentials; we might set up some of the more important instances using a dedicated role account
 * add some way to reauthorise an external bug tracker if the previous credentials expire or break or whatever

[Jeremy Bícha (jbicha)]

I guess these are the main gitlab instances we'd want (although there are several other smaller ones)

https://salsa.debian.org/
https://gitlab.gnome.org/
https://gitlab.freedesktop.org/ (new but I expect many important projects to move there soon)
https://gitlab.com/

[Wise Melon (wise-melon-deactivatedaccount)]

Given that all GNOME bugs are now being migrated to GitLab I think that it is important that support for this is worked on.

[Marco Trevisan (Treviño) (3v1n0)]

Yes please...

I did something for the bot, so once github [1] is set, having multiple gitlab instances is possible, although launchpad should subscribe for API tokens (and in case ask you need higher usage limits, ask upstream - GNOME one is happy to do that).

[1] https://code.launchpad.net/~3v1n0/ubuntu-bots/gitlab-support/

[Colin Watson (cjwatson)]

This turned out to be easier than we previously thought. I'm not sure whether I'd previously misunderstood the situation or whether something changed on the GitLab side, but William noticed that we can nowadays make the relevant queries without authentication, so we'll do that and see how things go.

[Launchpad QA Bot (lpqabot)]

Fixed in stable r18894 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/18894>.

[Colin Watson (cjwatson)]

I've just rolled this out, so GitLab bug watches and status syncing should work now. Please let us know (preferably via a new bug report) if you run into problems with it.