added metrics

cmd/main.go

@@ -18,6 +18,7 @@ package main //nolint:cyclop // main function needs to initialize many objects
 
 import (
 	"flag"
+	"github.com/kyma-project/nats-manager/internal/metrics"
 	"os"
 
 	nmapiv1alpha1 "github.com/kyma-project/nats-manager/api/v1alpha1"
@@ -150,6 +151,9 @@ func main() { //nolint:funlen // main function needs to initialize many objects
 
 	natsManager := nmmgr.NewNATSManger(kubeClient, helmRenderer, sugaredLogger)
 
+	collector := metrics.NewPrometheusCollector()
+	collector.RegisterMetrics()
+
 	// create NATS reconciler instance
 	natsReconciler := nmctrl.NewReconciler(
 		mgr.GetClient(),
@@ -165,6 +169,7 @@ func main() { //nolint:funlen // main function needs to initialize many objects
 				Namespace: envConfigs.NATSCRNamespace,
 			},
 		},
+		collector,
 	)
 
 	if err = (natsReconciler).SetupWithManager(mgr); err != nil {

internal/controller/nats/controller.go

@@ -19,6 +19,7 @@ package nats
 import (
 	"context"
 	"fmt"
+	"github.com/kyma-project/nats-manager/internal/metrics"
 
 	nmapiv1alpha1 "github.com/kyma-project/nats-manager/api/v1alpha1"
 	"github.com/kyma-project/nats-manager/pkg/events"
@@ -70,6 +71,7 @@ type Reconciler struct {
 	ctrlManager                 kcontrollerruntime.Manager
 	destinationRuleWatchStarted bool
 	allowedNATSCR               *nmapiv1alpha1.NATS
+	collector                   metrics.Collector
 }
 
 func NewReconciler(
@@ -81,6 +83,7 @@ func NewReconciler(
 	recorder record.EventRecorder,
 	natsManager nmmgr.Manager,
 	allowedNATSCR *nmapiv1alpha1.NATS,
+	collector metrics.Collector,
 ) *Reconciler {
 	return &Reconciler{
 		Client:                      client,
@@ -93,6 +96,7 @@ func NewReconciler(
 		natsManager:                 natsManager,
 		destinationRuleWatchStarted: false,
 		allowedNATSCR:               allowedNATSCR,
+		collector:                   collector,
 		controller:                  nil,
 	}
 }

internal/controller/nats/deprovisioner.go

@@ -24,6 +24,10 @@ const (
 func (r *Reconciler) handleNATSDeletion(ctx context.Context, nats *nmapiv1alpha1.NATS,
 	log *zap.SugaredLogger,
 ) (kcontrollerruntime.Result, error) {
+	// reset metrics.
+	r.collector.ResetAvailabilityZonesUsedMetric()
+	r.collector.ResetClusterSizeMetric()
+
 	// skip reconciliation for deletion if the finalizer is not set.
 	if !r.containsFinalizer(nats) {
 		log.Debugf("skipped reconciliation for deletion as finalizer is not set.")

internal/controller/nats/provisioner.go

@@ -23,6 +23,9 @@ func (r *Reconciler) handleNATSReconcile(ctx context.Context,
 ) (kcontrollerruntime.Result, error) {
 	log.Info("handling NATS reconciliation...")
 
+	// record metric.
+	r.collector.RecordClusterSizeMetric(nats.Spec.Cluster.Size)
+
 	// set status to processing
 	nats.Status.Initialize()
 	events.Normal(r.recorder, nats, nmapiv1alpha1.ConditionReasonProcessing, "Initializing NATS resource.")
@@ -101,6 +104,9 @@ func (r *Reconciler) handleNATSState(ctx context.Context, nats *nmapiv1alpha1.NA
 	nats.Status.AvailabilityZonesUsed, err = r.kubeClient.GetNumberOfAvailabilityZonesUsedByPods(ctx,
 		nats.GetNamespace(), getNATSPodsMatchLabels())
 
+	// record metric.
+	r.collector.RecordAvailabilityZonesUsedMetric(nats.Status.AvailabilityZonesUsed)
+
 	switch {
 	case err != nil:
 		nats.Status.UpdateConditionAvailabilityZones(kmetav1.ConditionFalse,

internal/controller/nats/unit_test.go

@@ -2,6 +2,7 @@ package nats
 
 import (
 	"context"
+	"github.com/kyma-project/nats-manager/internal/metrics"
 	"testing"
 
 	nmapiv1alpha1 "github.com/kyma-project/nats-manager/api/v1alpha1"
@@ -60,6 +61,9 @@ func NewMockedUnitTestEnvironment(t *testing.T, objs ...client.Object) *MockedUn
 	mockController := new(nmctrlmocks.Controller)
 	mockManager := new(nmctrlmocks.Manager)
 
+	// setup mocks.
+	collector := metrics.NewPrometheusCollector()
+
 	// setup reconciler
 	reconciler := NewReconciler(
 		fakeClient,
@@ -70,6 +74,7 @@ func NewMockedUnitTestEnvironment(t *testing.T, objs ...client.Object) *MockedUn
 		recorder,
 		natsManager,
 		nil,
+		collector,
 	)
 	reconciler.controller = mockController
 	reconciler.ctrlManager = mockManager

internal/metrics/metrics.go

@@ -0,0 +1,90 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"sigs.k8s.io/controller-runtime/pkg/metrics"
+)
+
+const (
+	// availabilityZonesUsedMetricKey name of the availability zones used metric.
+	availabilityZonesUsedMetricKey = "nats_manager_availability_zones_used"
+	// availabilityZonesUsedHelp help text for the availability zones used metric.
+	availabilityZonesUsedHelp = "The number of availability zones used used by NATS Pods."
+
+	// clusterSizeMetricKey name of the cluster size metric.
+	clusterSizeMetricKey = "nats_manager_cr_cluster_size"
+	// clusterSizeMetricHelp help text for the cluster size metric.
+	clusterSizeMetricHelp = "The cluster size configured in the NATS CR."
+)
+
+// Perform a compile time check.
+var _ Collector = &PrometheusCollector{}
+
+//go:generate go run github.com/vektra/mockery/v2 --name=Collector --outpkg=mocks --case=underscore
+type Collector interface {
+	RegisterMetrics()
+	RecordAvailabilityZonesUsedMetric(int)
+	RecordClusterSizeMetric(int)
+	ResetAvailabilityZonesUsedMetric()
+	ResetClusterSizeMetric()
+}
+
+// PrometheusCollector implements the prometheus.Collector interface.
+type PrometheusCollector struct {
+	availabilityZonesUsed *prometheus.GaugeVec
+	clusterSize           *prometheus.GaugeVec
+}
+
+// NewPrometheusCollector a new instance of Collector.
+func NewPrometheusCollector() Collector {
+	return &PrometheusCollector{
+		availabilityZonesUsed: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: availabilityZonesUsedMetricKey,
+				Help: availabilityZonesUsedHelp,
+			},
+			nil,
+		),
+		clusterSize: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: clusterSizeMetricKey,
+				Help: clusterSizeMetricHelp,
+			},
+			nil,
+		),
+	}
+}
+
+// Describe implements the prometheus.Collector interface Describe method.
+func (p *PrometheusCollector) Describe(ch chan<- *prometheus.Desc) {
+	p.availabilityZonesUsed.Describe(ch)
+	p.clusterSize.Describe(ch)
+}
+
+// Collect implements the prometheus.Collector interface Collect method.
+func (p *PrometheusCollector) Collect(ch chan<- prometheus.Metric) {
+	p.availabilityZonesUsed.Collect(ch)
+	p.clusterSize.Collect(ch)
+}
+
+// RegisterMetrics registers the metrics.
+func (p *PrometheusCollector) RegisterMetrics() {
+	metrics.Registry.MustRegister(p.availabilityZonesUsed)
+	metrics.Registry.MustRegister(p.clusterSize)
+}
+
+func (p *PrometheusCollector) RecordAvailabilityZonesUsedMetric(availabilityZonesUsed int) {
+	p.availabilityZonesUsed.WithLabelValues().Set(float64(availabilityZonesUsed))
+}
+
+func (p *PrometheusCollector) RecordClusterSizeMetric(clusterSize int) {
+	p.clusterSize.WithLabelValues().Set(float64(clusterSize))
+}
+
+func (p *PrometheusCollector) ResetAvailabilityZonesUsedMetric() {
+	p.availabilityZonesUsed.Reset()
+}
+
+func (p *PrometheusCollector) ResetClusterSizeMetric() {
+	p.clusterSize.Reset()
+}