RFE: please support dnf

[pcfe]

It would be nice if cephmetrics supported dnf.

I have some Fedora 29 ARM nodes in my Ceph cluster, thus I currently have to

ansible-playbook -v playbook.yml -e ansible_pkg_mgr=yum

Can you please add support for Fedora's default ansible_pkg_mgr=dnf?

[pcfe]

Since prometheus-node_exporter is not (yet) available in the Fedora repo, use the copr ibotty / prometheus-exporters when reproducing.

Or rebuild the RHEL7 SRPM. The following worked for me (built on one of my ARMv7 OSDs)

mock -r fedora-29-armhfp /var/tmp/golang-github-prometheus-node_exporter-0.15.2-2.el7cp.src.rpm