So, we are developing SLURM charms locally to build HPC systems. This field is dominated by rpm distros like centos and runs primarily on bare metal.
We face two large challenges with the juju domain.
MAAS loves Ubuntu, but has poor support for centos although we successfully roll custom centos images. But we run with decreased functionality, for example with storage/partitioning and inability to have more than one centos major version active at any time in MAAS. This makes it hard to upgrade custom images etc. Its not a juju problem, but it spills over to juju… For example, inability to deploy to updated images while keeping an old for rollback purposes.
We need to maintain two separate git code repos for rpm/centos resp. Ubuntu for mostly same functionality which requires double effort maintain and develop the same service - SLURM. It manifests itself for example that the metadata.yaml wont allow series: centos to be mixed with series: bionic. The charmstore wont allow that, git repos need to have separate branches or forks with different content in metadata.yaml and ultimately we end up having to maintain double code for the same service. This is a bad situation for a business primarily using centos/rpm as juju is heavily leaned towards Ubuntu/deb systems and poor on centos.
Although these above are a few issues we have with juju in a centos context , I would be helped with some advice how to keep a single git repo for both centos and Ubuntu to avoid having to duplicate work on our charms and to highligt that juju/maas needs more love on better supporting more than ubuntu distros…