Docker : thiner images

(from  GitLab Commit at KubeCon : One Layer Builds (Docker Not Included), by Jason Plum https://gitlab.com/WarheadsSE and Will Christensen)

* use FROM Scratch, instead of FROM <distro> 

 * Explore each layer of a docker image

https://github.com/wagoodman/dive 

* use Buildah : http://buildah.io/ "A tool that facilitates building OCI container images."

•     https://developers.redhat.com/blog/2021/01/11/getting-started-with-buildah
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