COPY from URL not supported as per documentation

[hmoffatt]

The Containerfile documentation (https://github.com/containers/common/blob/main/docs/Containerfile.5.md) says that you can use a URL with COPY, but it does not work, with buildah 1.31 at least:

The COPY instruction copies new files from and adds them to the filesystem of the container at path . The must be the path to a file or directory relative to the source directory that is being built (the context of the build) or a remote file URL.

Error: building at STEP "COPY --chmod=0755 https://... /some/path": source can't be a URL for COPY

[rhatdan]

Is this valid with Docker?

[hmoffatt]

No, it doesn't work in Docker either (and the instructions don't say it should - https://docs.docker.com/engine/reference/builder/#copy).