Check vendor

[dnephin]

Add a CI check for vendoring

[vdemeester]

LGTM 🐯
I wonder : should we run it only when vendor.conf or vendor/* files are changed, or always (as in this PR) ?

[gdevillele]

LGTM

but shouldn't we put the "vendor check" step before the "build+unit test" in circle.yml?

[dnephin]

Running it only when vendor* is changed is just an optimization, right?

My feeling is that it's not super necessary, and there are two advantages to avoiding it.

1. It means we don't have to worry about adding .git to any docker images. This lets us keep .git in .dockerignore for much faster builds. circleci doesn't support bind mount volumes with the remote engine, which we need to build images.
2. I always felt it was annoying having to commit before running any of the hack/validate scripts. I always felt that they should run on the current files, not the git diff.

I think we should avoid the optimization for now. When we need it, we could do it only in the circle ci config, instead of the makefile.

[dnephin]

but shouldn't we put the "vendor" step before the "build+unit test" in circle.yml

Ideally we would run them in parallel, but it's a bit more work to setup, and our build is probably fast enough right now that we can wait to do that work.

My reasoning for running it after build+test is that sometimes if you're modifying a dependency it is nice to be able to run tests with a custom version in vendor/ ahead of pushing it to master in the dependency repo. By putting it after binary and test, you can see if the change works, without having to commit it to the dependency repo.

[gdevillele]

@dnephin got it. Thanks 🙂