Move common code from osmo-*-latest to debian-stretch-obs-latest:
* add the OBS repository key
* add the OBS repository with "latest" feed
* install telnet
* invalidate the cache once the repository is updated
This is in preparation to make osmo-*-latest work with centos8,
preventing the following issues we would have without this refactoring:
* avoid need to read the repository index of both debian-stretch and
centos8, and to invalidate the cache if either of them changes
(instead of just the relevant one). This is currently a problem in
will fix it there.
* no need to add boilerplate code to install the centos8 repository to
While at it, also remove deprecated MAINTAINER lines.
Similar to what is already done with DISTRO, which points to given image
of ours based on name. This time we do the same with upstream images,
such as debian:stretch or centos:centos8.
This way, for instance calling docker_images_require
"osmo-bsc-latest-centos8" would try to build the
osmo-bsc-latest/Dockerfile file starting from a centos8 image.
This is initialized to docker.io, keeping the default behaviour
if not specified. However, it allows us to specify a private
registry later on.