metrics: add nfd_node_update_requests_total counter

Add a counter for total number of node update/sync requests. In
practice, this counts the number of gRPC requests received if the gRPC
API is in use. If the NodeFeature API is enabled, this counts the
requests initiated by the NFD API controller, i.e. updates triggered by
changes in NodeFeature or NodeFeatureRule objects plus updates initiated
by the controller resync period.

docs/deployment/metrics.md

@@ -17,6 +17,7 @@ The exposed metrics are
 | ------------------------------------------------- | --------- | ---------------------------------------
 | `nfd_master_build_info`                           | Gauge     | Version from which nfd-master was built
 | `nfd_worker_build_info`                           | Gauge     | Version from which nfd-worker was built
+| `nfd_node_update_requests_total`                  | Counter   | Number of node update requests processed by the master
 | `nfd_node_updates_total`                          | Counter   | Number of nodes updated
 | `nfd_node_update_failures_total`                  | Counter   | Number of nodes update failures
 | `nfd_node_labels_rejected_total`                  | Counter   | Number of nodes labels rejected by nfd-master

pkg/nfd-master/metrics.go

@@ -29,6 +29,7 @@ import (
 // When adding metric names, see https://prometheus.io/docs/practices/naming/#metric-names
 const (
 	buildInfoQuery           = "nfd_master_build_info"
+	nodeUpdateRequestsQuery  = "nfd_node_update_requests_total"
 	nodeUpdatesQuery         = "nfd_node_updates_total"
 	nodeUpdateFailuresQuery  = "nfd_node_update_failures_total"
 	nodeLabelsRejectedQuery  = "nfd_node_labels_rejected_total"
@@ -48,6 +49,10 @@ var (
 			"version": version.Get(),
 		},
 	})
+	nodeUpdateRequests = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: nodeUpdateRequestsQuery,
+		Help: "Number of node update requests processed by the master.",
+	})
 	nodeUpdates = prometheus.NewCounter(prometheus.CounterOpts{
 		Name: nodeUpdatesQuery,
 		Help: "Number of nodes updated by the master.",

pkg/nfd-master/nfd-master.go

@@ -654,6 +654,7 @@ func isNamespaceDenied(labelNs string, wildcardDeniedNs map[string]struct{}, nor
 
 // SetLabels implements LabelerServer
 func (m *nfdMaster) SetLabels(c context.Context, r *pb.SetLabelsRequest) (*pb.SetLabelsReply, error) {
+	nodeUpdateRequests.Inc()
 	err := authorizeClient(c, m.args.VerifyNodeName, r.NodeName)
 	if err != nil {
 		klog.ErrorS(err, "gRPC client authorization failed", "nodeName", r.NodeName)

pkg/nfd-master/node-updater-pool.go

@@ -46,6 +46,7 @@ func (u *nodeUpdaterPool) processNodeLabelRequest(queue workqueue.RateLimitingIn
 
 	defer queue.Done(nodeName)
 
+	nodeUpdateRequests.Inc()
 	if err := u.nfdMaster.nfdAPIUpdateOneNode(nodeName.(string)); err != nil {
 		if queue.NumRequeues(nodeName) < 5 {
 			klog.InfoS("retrying labeling request for node", "nodeName", nodeName)