Git authentication secrets documentation issue

[pcuriel]

Hi!

I have found that the documentation regarding the usage of Git authentication secrets is not correct.

On the one hand, it says that "By default, Git authentication over HTTP uses the Bearer authentication scheme". But actually:

• When using the GIT_AUTH_TOKEN secret, Basic auth is used, but setting the username to the fixed value "x-access-token".
• When using the GIT_AUTH_HEADER secret, auth type must be externally provided.

On the other hand, the examples using GIT_AUTH_HEADER are wrong. According to the docs, it seems that both GIT_AUTH_TOKEN and GIT_AUTH_HEADER must be provided. The former with the username and password value, and the latter with a fixed "basic" value.

$ export GIT_AUTH_TOKEN=$(cat gitlab-token.txt)
$ export GIT_AUTH_HEADER=basic
$ docker build \
  --secret id=GIT_AUTH_TOKEN \
  --secret id=GIT_AUTH_HEADER \
  https://gitlab.com/example/todo-app.git

However, looking at the code, either one of GIT_AUTH_TOKEN or GIT_AUTH_HEADER must be provided.

In summary, it would be really helpful if, in addition to fixing the instructions, docs really stated what is happening behind the scenes:

• If GIT_AUTH_TOKEN is used, the value provided is sent as follows: Authorization: basic x-access-token:<PROVIDED VALUE>(base64 encoded)
• If GIT_AUTH_HEADER is used, the value provided is sent as follows: Authorization: <PROVIDED VALUE>