docker-credential-gcr produces Username incompatible with GCR when used by other libraries

[dinvlad]

Actual behavior
echo https://gcr.io | docker-credential-gcr get produces output like this:

{"ServerURL":"https://gcr.io","Username":"_dcgcr__token","Secret":"<redacted_oauth_token>"}

When using this helper with other libraries like Jib, they fail to successfully authenticate against GCR because GCR would not accept the username in the format _dcgcr__token (note the 2 _s between dcgcr and token).

But when docker-credential-gcr is build from the latest source, it produces Username in the format _dcgcr_2_0_4_token,
which is accepted by GCR when using basic auth.

Expected behavior
docker-credential-gcr get should produce Username that has version between dcgcr and token, which works with GCR.

To Reproduce
Please see the commands above.

Additional Information

• Dockerfile
  N/A
• Build Context
  N/A
• Kaniko Image (fully qualified with digest)
  gcr.io/kaniko-project/executor@sha256:a3f8c85c6a0fa490b9a619bdb503c8cb98fb2fd17f96d0e4356a0bd65c1e5056 (:debug)
  gcr.io/kaniko-project/executor@sha256:1f982af0b54be748221d9a35dcfa608660ab3d51229aa56bde5416f75aff7561 (:latest)

I believe this issue is due to the version information somehow not being bundled with the build used (even though it shows up as v1.5.1-0.20210909233216-4cdd60d0f2d8 on version command).

I would suggest to update the binary to the latest version and make sure it outputs Username in the right format.

Triage Notes for the Maintainers

Description	Yes/No
Please check if this a new feature you are proposing
Please check if the build works in docker but not in kaniko
Please check if this error is seen when you use --cache flag
Please check if your dockerfile is a multistage dockerfile