We actually have to count or sum, respectively, _all_ the selected
metrics for the cluster-wide view. Which means it's easiest to use the
`scalar` approach after all (but only in the cluster dashboard). This
still propagates all the labels.
I have extended the comment for the `nodeExporterSelector` to note
that the cluster dashboard only makes sense if all the selected node
exporter actually belong to the same cluster.
Since this is jsonnet, users can easily disable the cluster
dashboard. Or even create multiple instances of the dashboards with
different `nodeExporterSelector`s for different clusters.
Signed-off-by: beorn7 <beorn@grafana.com>
c6914477f5