Pull a file from a docker image in Golang to local file system

I’m trying to figure out how I can use the Go client (http://godoc.org/github.com/moby/moby/client) to pull a file from a docker image at a specific version (tag)

I want to download the image and then copy a file from the image onto the local file system. I see a lot of commands for dealing with an image, but not how to access its contents. I do see ways to access a container’s contents.

I’m suspecting I would need to download the image, create a container with the image and finally copy the contents out of the container. Though if I could avoid creating a container, that would be preferred.

Does anyone know exactly how to do this? Code snippet would be appreciated.