We use a plain ubuntu container as a build environment for ethtool &
conntrack, so a) we don't require onerous tooling on the build host,
and b) don't pollute the build host with build artefacts. The latter
arise because I can only get conntrack to build by installing its
dependencies 'globally'.
Th dir containing the build script is volume-mounted into the
container, and that is where we also expect to see the result, namely
a 'bin' sub-dir containing two executables.
The weavetools image is then constructed from the 'scratch' image and
contains just that dir.
Matthias Radestock