wut???

See https://github.com/tianon/docker-containerd-tags/tags.

how?

17.06 and newer

https://github.com/docker/docker/releases

Choose a version:

$ git ls-remote --tags https://github.com/docker/docker-ce.git 'refs/tags/v*' \
	| cut -d/ -f3 \
	| cut -d'^' -f1 \
	| sort -uV

Get the relevant commit:

$ version='v17.06.0-ce-rc5'
$ wget -qO- "https://github.com/docker/docker-ce/raw/$version/components/engine/hack/dockerfile/binaries-commits" \
	| grep -E '^CONTAINERD_COMMIT=' \
	| cut -d= -f2

17.05 and older

https://github.com/docker/docker/releases

Choose a version:

$ git ls-remote --tags https://github.com/docker/docker.git 'refs/tags/v*' \
	| cut -d/ -f3 \
	| cut -d'^' -f1 \
	| sort -uV

Get the relevant commit:

$ version='v17.05.0-ce'
$ wget -qO- "https://github.com/docker/docker/raw/$version/hack/dockerfile/binaries-commits" \
	| grep -E '^CONTAINERD_COMMIT=' \
	| cut -d= -f2

making the tag

Get the commit object:

$ commit='cfb82a876ecc11b5ca0977d1733adbe58599088a'
$ git fetch --no-tags https://github.com/containerd/containerd.git refs/heads/*:refs/remotes/containerd/*
$ git fetch --no-tags https://github.com/docker/containerd.git refs/heads/*:refs/remotes/docker-containerd/*
$ git show "$commit" # to verify it actually exists

Push it!

$ tag="${version#v}"; tag="${tag//-ce/}"; tag="docker-$tag"
$ echo "$tag"
$ git push origin "$commit":"refs/tags/$tag"