zoneHealthStatisticKey  = "zone_health"
	zoneSizeKey             = "zone_size"
	zoneNoUnhealthyNodesKey = "unhealthy_nodes_in_zone"
	evictionsTotalKey       = "evictions_total"

	updateNodeHealthKey     = "update_node_health_duration_seconds"
	updateAllNodesHealthKey = "update_all_nodes_health_duration_seconds"
)

var (
	zoneHealth = metrics.NewGaugeVec(
		&metrics.GaugeOpts{
			Subsystem:      nodeControllerSubsystem,