Description

Not sure if this is a feature or bug, as Docker documentation does not mention this limitation: https://docs.docker.com/reference/cli/docker/#custom-http-headers

Also, Sample configuration file section in the docs includes an example of headers "MyHeader": "MyValue" which will never be sent due to existing limitation.

There is an open bug in the docker/docs repo that has been open for almost 5 years.

The feature was introduced for the first time in this PR.
Currently, the limitation is in two places: daemon/server/router/image, daemon/server/router/plugin

So, the question is, could this limitation be either dropped (preferred option 🙂) or documented?

The real-life example: we could host a private registry behind Cloudflare's zero trust and access the registry with custom headers. But it could be any other similar authentication/authorization layer that requires custom auth headers for passing requests.

If code owners decide to drop that limitation, I would love to try to implement it.