Fix error when the operator metrics ServiceMonitor already exists

.chloggen/3446.yaml

@@ -0,0 +1,19 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'bug_fix'
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: operator
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Operator pod crashed if the Service Monitor for the operator metrics was created before by another operator pod.
+
+# One or more tracking issues related to the change
+issues: [3446]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Operator fails when the pod is restarted and the Service Monitor for operator metrics was already created by another operator pod.
+  To fix this, the operator now sets the owner reference on the Service Monitor to itself and checks if the Service Monitor already exists.
+

internal/operator-metrics/metrics.go

@@ -19,8 +19,11 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/go-logr/logr"
 	monitoringv1 "github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring/v1"
+	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
@@ -51,26 +54,35 @@ var _ manager.Runnable = &OperatorMetrics{}
 
 type OperatorMetrics struct {
 	kubeClient client.Client
+	log        logr.Logger
 }
 
-func NewOperatorMetrics(config *rest.Config, scheme *runtime.Scheme) (OperatorMetrics, error) {
+func NewOperatorMetrics(config *rest.Config, scheme *runtime.Scheme, log logr.Logger) (OperatorMetrics, error) {
 	kubeClient, err := client.New(config, client.Options{Scheme: scheme})
 	if err != nil {
 		return OperatorMetrics{}, err
 	}
 
 	return OperatorMetrics{
 		kubeClient: kubeClient,
+		log:        log,
 	}, nil
 }
 
 func (om OperatorMetrics) Start(ctx context.Context) error {
 	rawNamespace, err := os.ReadFile(namespaceFile)
 	if err != nil {
-		return fmt.Errorf("error reading namespace file: %w", err)
+		om.log.Error(err, "error reading namespace file. No ServiceMonitor will be created")
+		return nil
 	}
 	namespace := string(rawNamespace)
 
+	ownerRef, err := om.getOwnerReferences(ctx, namespace)
+	if err != nil {
+		om.log.Error(err, "error getting owner references. No ServiceMonitor will be created")
+		return nil
+	}
+
 	var tlsConfig *monitoringv1.TLSConfig
 
 	if om.caConfigMapExists() {
@@ -101,6 +113,7 @@ func (om OperatorMetrics) Start(ctx context.Context) error {
 				"app.kubernetes.io/part-of": "opentelemetry-operator",
 				"control-plane":             "controller-manager",
 			},
+			OwnerReferences: []metav1.OwnerReference{ownerRef},
 		},
 		Spec: monitoringv1.ServiceMonitorSpec{
 			Selector: metav1.LabelSelector{
@@ -123,7 +136,8 @@ func (om OperatorMetrics) Start(ctx context.Context) error {
 	}
 
 	err = om.kubeClient.Create(ctx, &sm)
-	if err != nil {
+	// The ServiceMonitor can be already there if this is a restart
+	if err != nil && !apierrors.IsAlreadyExists(err) {
 		return fmt.Errorf("error creating service monitor: %w", err)
 	}
 
@@ -143,3 +157,34 @@ func (om OperatorMetrics) caConfigMapExists() bool {
 	}, &corev1.ConfigMap{},
 	) == nil
 }
+
+func (om OperatorMetrics) getOwnerReferences(ctx context.Context, namespace string) (metav1.OwnerReference, error) {
+	var deploymentList appsv1.DeploymentList
+
+	listOptions := []client.ListOption{
+		client.InNamespace(namespace),
+		client.MatchingLabels(map[string]string{
+			"app.kubernetes.io/name": "opentelemetry-operator",
+			"control-plane":          "controller-manager",
+		}),
+	}
+
+	err := om.kubeClient.List(ctx, &deploymentList, listOptions...)
+	if err != nil {
+		return metav1.OwnerReference{}, err
+	}
+
+	if len(deploymentList.Items) == 0 {
+		return metav1.OwnerReference{}, fmt.Errorf("no deployments found with the specified label")
+	}
+	deployment := &deploymentList.Items[0]
+
+	ownerRef := metav1.OwnerReference{
+		APIVersion: "apps/v1",
+		Kind:       "Deployment",
+		Name:       deployment.Name,
+		UID:        deployment.UID,
+	}
+
+	return ownerRef, nil
+}

internal/operator-metrics/metrics_test.go

@@ -17,26 +17,30 @@ package operatormetrics
 import (
 	"context"
 	"os"
+	"reflect"
 	"testing"
 	"time"
 
+	"github.com/go-logr/logr"
 	monitoringv1 "github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring/v1"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/fake"
 )
 
 func TestNewOperatorMetrics(t *testing.T) {
 	config := &rest.Config{}
 	scheme := runtime.NewScheme()
-	metrics, err := NewOperatorMetrics(config, scheme)
+	metrics, err := NewOperatorMetrics(config, scheme, logr.Discard())
 	assert.NoError(t, err)
 	assert.NotNil(t, metrics.kubeClient)
 }
@@ -53,12 +57,15 @@ func TestOperatorMetrics_Start(t *testing.T) {
 	namespaceFile = tmpFile.Name()
 
 	scheme := runtime.NewScheme()
-	err = corev1.AddToScheme(scheme)
-	require.NoError(t, err)
-	err = monitoringv1.AddToScheme(scheme)
-	require.NoError(t, err)
+	require.NoError(t, corev1.AddToScheme(scheme))
+	require.NoError(t, appsv1.AddToScheme(scheme))
+	require.NoError(t, monitoringv1.AddToScheme(scheme))
 
-	client := fake.NewClientBuilder().WithScheme(scheme).Build()
+	client := fake.NewClientBuilder().WithScheme(scheme).WithRuntimeObjects(
+		&appsv1.Deployment{
+			ObjectMeta: metav1.ObjectMeta{Name: "opentelemetry-operator", Namespace: "test-namespace", Labels: map[string]string{"app.kubernetes.io/name": "opentelemetry-operator", "control-plane": "controller-manager"}},
+		},
+	).Build()
 
 	metrics := OperatorMetrics{kubeClient: client}
 
@@ -125,3 +132,70 @@ func TestOperatorMetrics_caConfigMapExists(t *testing.T) {
 	metricsWithoutConfigMap := OperatorMetrics{kubeClient: clientWithoutConfigMap}
 	assert.False(t, metricsWithoutConfigMap.caConfigMapExists())
 }
+
+func TestOperatorMetrics_getOwnerReferences(t *testing.T) {
+	tests := []struct {
+		name      string
+		namespace string
+		objects   []client.Object
+		want      metav1.OwnerReference
+		wantErr   bool
+	}{
+		{
+			name:      "successful owner reference retrieval",
+			namespace: "test-namespace",
+			objects: []client.Object{
+				&appsv1.Deployment{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "opentelemetry-operator",
+						Namespace: "test-namespace",
+						UID:       "test-uid",
+						Labels: map[string]string{
+							"app.kubernetes.io/name": "opentelemetry-operator",
+							"control-plane":          "controller-manager",
+						},
+					},
+				},
+			},
+			want: metav1.OwnerReference{
+				APIVersion: "apps/v1",
+				Kind:       "Deployment",
+				Name:       "opentelemetry-operator",
+				UID:        "test-uid",
+			},
+			wantErr: false,
+		},
+		{
+			name:      "no deployments found",
+			namespace: "test-namespace",
+			objects:   []client.Object{},
+			want:      metav1.OwnerReference{},
+			wantErr:   true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			scheme := runtime.NewScheme()
+			_ = appsv1.AddToScheme(scheme)
+			fakeClient := fake.NewClientBuilder().
+				WithScheme(scheme).
+				WithObjects(tt.objects...).
+				Build()
+
+			om := OperatorMetrics{
+				kubeClient: fakeClient,
+				log:        logr.Discard(),
+			}
+
+			got, err := om.getOwnerReferences(context.Background(), tt.namespace)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("getOwnerReferences() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("getOwnerReferences() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

main.go

@@ -424,7 +424,7 @@ func main() {
 	}
 
 	if cfg.PrometheusCRAvailability() == prometheus.Available {
-		operatorMetrics, opError := operatormetrics.NewOperatorMetrics(mgr.GetConfig(), scheme)
+		operatorMetrics, opError := operatormetrics.NewOperatorMetrics(mgr.GetConfig(), scheme, ctrl.Log.WithName("operator-metrics-sm"))
 		if opError != nil {
 			setupLog.Error(opError, "Failed to create the operator metrics SM")
 		}