Set replicas to default value

apis/v1alpha1/opentelemetrycollector_webhook.go

@@ -40,6 +40,8 @@ var _ webhook.Defaulter = &OpenTelemetryCollector{}
 
 // Default implements webhook.Defaulter so a webhook will be registered for the type.
 func (r *OpenTelemetryCollector) Default() {
+	opentelemetrycollectorlog.Info("default", "name", r.Name)
+
 	if len(r.Spec.Mode) == 0 {
 		r.Spec.Mode = ModeDeployment
 	}
@@ -54,7 +56,12 @@ func (r *OpenTelemetryCollector) Default() {
 		r.Labels["app.kubernetes.io/managed-by"] = "opentelemetry-operator"
 	}
 
-	opentelemetrycollectorlog.Info("default", "name", r.Name)
+	if r.Spec.Replicas == nil {
+		// We can default to one because dependent objects Deployment and HorizontalPodAutoScaler
+		// default to 1 as well.
+		one := int32(1)
+		r.Spec.Replicas = &one
+	}
 }
 
 // +kubebuilder:webhook:verbs=create;update,path=/validate-opentelemetry-io-v1alpha1-opentelemetrycollector,mutating=false,failurePolicy=fail,groups=opentelemetry.io,resources=opentelemetrycollectors,versions=v1alpha1,name=vopentelemetrycollectorcreateupdate.kb.io,sideEffects=none,admissionReviewVersions=v1

apis/v1alpha1/opentelemetrycollector_webhook_test.go

@@ -0,0 +1,64 @@
+package v1alpha1
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestOELColDefaultingWebhook(t *testing.T) {
+	one := int32(1)
+	five := int32(5)
+	tests := []struct {
+		name     string
+		otelcol  OpenTelemetryCollector
+		expected OpenTelemetryCollector
+	}{
+		{
+			name:    "all fields default",
+			otelcol: OpenTelemetryCollector{},
+			expected: OpenTelemetryCollector{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"app.kubernetes.io/managed-by": "opentelemetry-operator",
+					},
+				},
+				Spec: OpenTelemetryCollectorSpec{
+					Mode:            ModeDeployment,
+					Replicas:        &one,
+					UpgradeStrategy: UpgradeStrategyAutomatic,
+				},
+			},
+		},
+		{
+			name: "provided values in spec",
+			otelcol: OpenTelemetryCollector{
+				Spec: OpenTelemetryCollectorSpec{
+					Mode:            ModeSidecar,
+					Replicas:        &five,
+					UpgradeStrategy: "adhoc",
+				},
+			},
+			expected: OpenTelemetryCollector{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"app.kubernetes.io/managed-by": "opentelemetry-operator",
+					},
+				},
+				Spec: OpenTelemetryCollectorSpec{
+					Mode:            ModeSidecar,
+					Replicas:        &five,
+					UpgradeStrategy: "adhoc",
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			test.otelcol.Default()
+			assert.Equal(t, test.expected, test.otelcol)
+		})
+	}
+}