Set replicas to default value (open-telemetry#814)

* Set replicas to default value

Signed-off-by: Pavol Loffay <p.loffay@gmail.com>

* Fix

Signed-off-by: Pavol Loffay <p.loffay@gmail.com>

* Fix

Signed-off-by: Pavol Loffay <p.loffay@gmail.com>

* Fix

Signed-off-by: Pavol Loffay <p.loffay@gmail.com>

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
@@ -86,11 +93,6 @@ func (r *OpenTelemetryCollector) validateCRDSpec() error {
 		return fmt.Errorf("the OpenTelemetry Collector mode is set to %s, which does not support the attribute 'volumeClaimTemplates'", r.Spec.Mode)
 	}
 
-	// validate replicas
-	if (r.Spec.Mode == ModeSidecar || r.Spec.Mode == ModeDaemonSet) && r.Spec.Replicas != nil {
-		return fmt.Errorf("the OpenTelemetry Collector mode is set to %s, which does not support the attribute 'replicas'", r.Spec.Mode)
-	}
-
 	// validate tolerations
 	if r.Spec.Mode == ModeSidecar && len(r.Spec.Tolerations) > 0 {
 		return fmt.Errorf("the OpenTelemetry Collector mode is set to %s, which does not support the attribute 'tolerations'", r.Spec.Mode)

apis/v1alpha1/opentelemetrycollector_webhook_test.go

@@ -0,0 +1,78 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1alpha1
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestOTELColDefaultingWebhook(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)
+		})
+	}
+}