fix: Use Gitlab's pending status when the commit status is pending

[william-richard]

what

Unlike Gitlab, Github's commit statuses do not have a "running" state, so the atlantis flow doesn't have a concept for "running". Instead of adding complexity for the majority use case (Github), I think a clear user experience is to map "pending" to "pending" for Gitlab, and let commit statuses go from pending to either success or failure.

Along with #3378, this change should result in a better user experience for Gitlab users.

why

• See
• This absolutely is getting in the way of gitlab MR automation, since sometimes you can get a commit status stuck in "running" forever, and never clear the MR status.

tests

• I ran atlantis locally against my company's gitlab instance, and it updated the commit statuses accurately

references

Perhaps closes #2125

[jamengual]

@lukemassa @X-Guardian

[lukemassa]

Unfortunately I don't think this addresses the issue. From gitlab's perspective, after one successful plan, the pipeline is still not "successful", so both humans and automation are likely to be confused about what to do.

Additionally, in the time after atlantis plan but before the plan be pasted into a comment, the pipelines look like this:

which to me doesn't capture the fact that a plan is "running" (i.e. terraform is happening, stuff is going).

I think there are definitely changes to be made to better map states between the different VCSs, per @X-Guardian 's comment #2125 (comment) , it is tricky because atlantis uses one set of terminologies whereas github and gitlab use different ones (kind of like atlantis using PR like github whereas gitlab uses MR). Let me think about this one.

That said, I still think that #2125 is not a VCS-specific problem and should be addressed in i.e. plan_command_runner.go.