Problem description
===================
Today we have some hardcoded pollsters that are gathering
data from running virtual machines through libvirt or
different programs running in the compute nodes. However,
the Dynamic pollster definition does not support this kind of
operations to gather data, it only supports HTTP Rest
requests to collect data. Therefore, it is not possible to
use the dynamic pollster definition to create a YML based
pollster that runs and collects data from Libvirt in the
compute nodes.
Proposal
========
To allow host commands/scripts in the Dynamic pollsters,
we propose to add a new pollster definition using the
`os.subprocess` lib to run host commands to collect
Host/VMs data and store them in the configured backend.
This will provide more flexibility and make the
Dynamic pollsters able to be used in Ceilometer compute
instances as well.
Change-Id: I50b8dc341ce457780416b41d138e35f5a0d083b6
Depends-On: https://review.opendev.org/c/openstack/ceilometer/+/850253
cb448a1dbc