how do you use git-credentials inside a Dockerfile?

[cellog]

The docs for git-credentials don't actually specify that it has to be a git credential helper. I figured that out from looking at the source, but even that was not enough to get it working.

...So, how do you use git-credentials?

[camallen]

I'd love to know the answer to this as well, https://forum.buildkite.community/t/use-git-credentials-in-a-docker-container/3137