CI should run gofmt/goimports and govet

[grantr]

Expected Behavior

Code that has not been properly formatted fails CI and cannot be merged.

Actual Behavior

Code is able to be merged without having the correct golang formatting (see here).

Steps to Reproduce the Problem

1. Create a PR containing code that hasn't been formatted or vetted.
2. Observe that no status check fails.

@adrcunha WDYT? This could be a separate check that runs gofmt (or goimports) and govet and fails when they generate changes or warnings.

[adrcunha]

SGTM. Easy to do, and useful.

[adrcunha]

Steps:

1. Create a script to run gofmt (or goimports) and govet (can be a simple branch of hack/coverage.sh)
2. Create a prow test job to run the script on every pull request.

[adrcunha]

/lint plugin is currently enabled for prow, but looks like it's not working. I'm investigating.

[adrcunha]

Cole fixed the issue that was preventing the lint plugin from working:

kubernetes/test-infra#7719

[adrcunha]

@cjwagner explained that the golint plugin doesn't run automatically because it is only applicable to some PRs and leaves long reviews. If we ran it everywhere it would quickly be dubbed spam. It is also a pretty expensive operation compared to most plugins. If it was migrated to an external plugin it could be updated to run automatically in certain repos.

@grantr is /lint good enough for our purposes? I prefer it than a hard-to-read output like what I proposed in my second comment.

[grantr]

/lint is fine. My preference would be to have both: a status check to let reviewers know linters failed (perhaps optional for merging) and /lint to turn the results into easy-to-read comments.

[grantr]

@adrcunha since we have /lint for now, I'll close this and we can open a separate issue if we still want prow to run linters automatically.

[adrcunha]

SGTM