The static binary install dose not include cli-plugins (buildx, app)

[BarnabyShearer]

• This is a bug report
• This is a feature request
• I searched existing issues before opening this one

Expected behavior

The 19.03.0 client release notes include "Added support for Docker buildx.", and the various distribution packages all include the cli-plugins. It seems reasonable to expect that the static binary release also would.
This is exacerbated by the usage documentation implying you can expect DOCKER_CLI_EXPERIMENTAL=enabled docker buildx to just work; and the error message docker buildx build --platform linux/amd64 "unknown flag: --platform" not being clear you are missing a plugin.
This has caused issues like docker-library/docker#156 in the downstream docker image.

Actual behavior

curl -s https://download.docker.com/linux/static/stable/x86_64/docker-19.03.9.tgz | tar -tz
docker/
docker/docker-init
docker/runc
docker/docker
docker/docker-proxy
docker/containerd
docker/ctr
docker/dockerd
docker/containerd-shim

[cpuguy83]

@tiborvass

[thaJeztah]

Relates to docker/docker-ce-packaging#415. Discussion was still ongoing if the plugins should be included in the static packages, or if they should be in a separate tar.gz to keep size down, and/or in favour of the github release of the plugins (e.g. https://github.com/docker/buildx/releases)