Adapt the Makefile and Dockerfile for a multi-stage build of the
container image. It is now not anymore required to have go locally
installed to build the container image.
Inside the multi-stage build, the newly create make install command will
be executed. The compbiled files will than be copied to a new base image
with less dependencies.
Further improvement would be to use instead of debian:10 scratch,
because the application does not have any C dependencies
(CGO_ENABLED=0).
Additionally it is not possible to build the container image with
alternative container runtimes like podman instead of docker.
make build/container-image CONTAINER_RUNTIME=podman
The used base image names are now defined as fully qualified image names
(with registry host), to support local container registry mirror
configurations.
