Add gitlab support

[vavilen84]

@tstromberg Hi! This draft PR is just to sync with you - if I am on the right way.

Main idea of this PR is to separate 'github' via new 'models' layer.

I created new packages:

• models (I plan to use these entities instead of github types)
• constants (just refactoring)
• interfaces (just refactoring)
• provider (this package shouild contain provider specific logic.
  by design, I plan to support both providers simultaneously, which will be determined by the host github.com/gitlab.com)
• utils (just refactoring)

Please correct me if you see the implementation differently or you have any wishes. Thanks!

P.S. code doesnt work for now - this PR is just to sync with you.

[vavilen84]

Great news! Application started with empty models data:

now I need to set github types data to application types in pkg/provider/github.go . After this need to test.

[vavilen84]

Triage-party alive again!

Next step - implement gitlab API.

[vavilen84]

Gitlab works! But for now only if we use "closed-milestone-issues" rule:

Current implementation needs debuging.

[vavilen84]

@tstromberg PR is ready for review. Gitlab works!:

But, during integration I had concerns:

1. I have not found gitlab analogue for github method Issues.ListIssueTimeline https://github.com/google/triage-party/blob/master/pkg/hubbub/timeline.go#L52. It seems that gitlab don`t provide events by issue number, but i could be wrong. For now this method implementation for gitlab returns empty result.

2. Gitlab 'Notes' API https://docs.gitlab.com/ee/api/notes.html returns 404 but should not:

3. I filled application models from gitlab models relying on my intuition and the time that I devoted to this project is not enough to know all its subtleties. I think need person who can test this implementation.

[tstromberg]

This is quite the tour de force. I've only given it a cursory review so far, but have some minor comments. Overall idea is solid.

I noticed that the models contain a lot of methods we do not make use of - would it be possible to cull the dead code before merging this? For example: issue.GetNodeID, issue.GetLocked.

[tstromberg]

Thank you for your patience. Looks good!

[vavilen84]

@tstromberg Hey, I see the master have new changes and there are conflicts here. Does it make sense for me to solve these conflicts? Do you have the intention to merge this PR to master?

[tstromberg]

Hey @vavilen84 - sorry for not updating this PR!

I did some pre-merge testing last week and discovered that it seemed to break GitHub support:

go build cmd/server/main.go && ./main --github-token-file ~/.github-private-token --config config/examples/minikube.yaml 
I0901 07:55:38.189273   13713 disk.go:152] default disk path: pcache/minikube.yaml.pc
I0901 07:55:38.189375   13713 disk.go:50] Initializing with pcache/minikube.yaml.pc ...
I0901 07:55:38.189855   13713 disk.go:52] recreating cache due to load error: decode failed: gob: name not registered for interface: "*persist.Thing"
I0901 07:55:38.189879   13713 disk.go:105] *** Saving 0 items to disk cache at pcache/minikube.yaml.pc
I0901 07:55:38.191838   13713 provider.go:58] loaded 41 byte github/gitlab token from /Users/tstromberg/.github-private-token
I0901 07:55:38.191870   13713 provider.go:60] loaded 0 byte github/gitlab token from GITLAB_TOKEN
F0901 07:55:38.191876   13713 provider.go:65] github/gitlab token impossibly small: ""

Do you mind addressing this issue? I can then merge this PR.

[vavilen84]

@tstromberg Unwanted provider initiating is fixed - please, review.

[tstromberg]

This looks better. Thank you! Please resolve the merge conflicts and we are good to merge.

[vavilen84]

@tstromberg Conflicts were resolved. Please, review.

[tstromberg]

Thank you!