Starting container process caused "exec: \"/bin/sh\": stat /bin/sh: no such file or directory": unknown
There are two things happening here.
A Dockerfile that starts
FROM scratch starts from a base image that has absolutely nothing at all in it. It is totally empty. There is not a set of base tools or libraries or anything else, beyond a couple of device files Docker pushes in for you.
ENTRYPOINT echo ... command gets rewritten by Docker into
ENTRYPOINT ["/bin/sh", "-c", "echo ..."], and causes the
CMD to be totally ignored. Unless overridden with
docker run --entrypoint, this becomes the main process the container runs.
Since it is a
FROM scratch image and contains absolutely nothing at all, it doesn't contain a shell, hence the "/bin/sh: no such file or directory" error.