Ensure that branch has been updated to point off of master

[atlantisbot]

Issue by @lkysow
Tuesday Sep 05, 2017 at 01:54 GMT
Migrated from hootsuite/atlantis#143
Why was it migrated?

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Right now we don't check whether a branch has been updated to the latest master. We should just error out if it hasn't, otherwise the plan will be weird.

[atlantisbot]

Comment by @grobie
Thursday Feb 15, 2018 at 17:36 GMT

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That wouldn't work well for us. While we don't have a company-wide monorepo, we do have one for all infrastructure changes. There can be tens of unrelated commits in the same repository per hour.

A better approach would be to ensure that the commit of the latest applied state is in the history of the current commit. I'll explain that tomorrow in our call.

[atlantisbot]

Comment by @lkysow
Thursday Feb 15, 2018 at 21:21 GMT

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Ahh interesting, I should have thought of that. Right now Atlantis just uses a file-based key-value store which is "okay" to lose because all it records are locks. It might be dangerous to rely on that store for looking up commit => state information.

At some point we'll move to an actual DB which might enable that better. I agree that that would be the most exact way to ensure the pull request is up to date.

[majormoses]

I think there is some middle ground here since at least in the case of github that is a type of branch protection. If its enabled we should honor it and not allow the plan to run and otherwise give people enough rope to hang themselves.

[sstarcher]

I think it would be great to attempt to auto-rebase on master. This is a feature that a tool like Jenkins supports.

[majormoses]

Ya auto rebase off master when possible would be awesome.

[sstarcher]

@lkysow should this issue be closed as won't fix due to #374 being rejected in preference for custom workflows?

[lkysow]

The original issue was about warning users if they were generating a plan from a pull request that was out of date with master. This hasn't been solved so I don't think it makes sense to close the issue.

Even with the warning, we have to find a way to deal with the case of users who don't use master as the default branch.

[sstarcher]

Sure, the branch could be configurable, but if you just supported rebasing onto whatever that branch is out of the box it would resolve both cases. I don't understand how this is a desirable feature, but #374 was not

[majormoses]

We can query the repo for the name of the default_branch: https://developer.github.com/v3/repos/#get