Use the metrics provided by the node_exporter for node-level resources.
This is much more efficient, especially for memory, as it's only two
metrics per node, rather than based on the number of running containers.
Signed-off-by: SuperQ <superq@gmail.com>
This introduces support for the resource metrics in the adapter.
The individual queries and window sizes are fully customizable via a new
config section. This uses just the generic machinery from
metrics-server to serve the API.
