Change horizontal pod autoscaler to use otelcol scale subresource

Makefile

@@ -152,7 +152,7 @@ e2e:
 	$(KUTTL) test
 
 .PHONY: prepare-e2e
-prepare-e2e: kuttl set-test-image-vars set-image-controller container container-target-allocator start-kind load-image-all
+prepare-e2e: kuttl set-test-image-vars set-image-controller container container-target-allocator start-kind install-metrics-server load-image-all
 	mkdir -p tests/_build/crds tests/_build/manifests
 	$(KUSTOMIZE) build config/default -o tests/_build/manifests/01-opentelemetry-operator.yaml
 	$(KUSTOMIZE) build config/crd -o tests/_build/crds/
@@ -184,6 +184,10 @@ container-target-allocator:
 start-kind:
 	kind create cluster --config $(KIND_CONFIG)
 
+.PHONY: install-metrics-server
+install-metrics-server:
+	./hack/install-metrics-server.sh
+
 .PHONY: load-image-all
 load-image-all: load-image-operator load-image-target-allocator
 

apis/v1alpha1/opentelemetrycollector_types.go

@@ -37,6 +37,10 @@ type OpenTelemetryCollectorSpec struct {
 	// +optional
 	Replicas *int32 `json:"replicas,omitempty"`
 
+	// MinReplicas sets a lower bound to the autoscaling feature.
+	// +optional
+	MinReplicas *int32 `json:"minReplicas,omitempty"`
+
 	// MaxReplicas sets an upper bound to the autoscaling feature. If MaxReplicas is set autoscaling is enabled.
 	// +optional
 	MaxReplicas *int32 `json:"maxReplicas,omitempty"`

bundle/manifests/opentelemetry.io_opentelemetrycollectors.yaml

@@ -223,6 +223,10 @@ spec:
                   If MaxReplicas is set autoscaling is enabled.
                 format: int32
                 type: integer
+              minReplicas:
+                description: MinReplicas sets a lower bound to the autoscaling feature.
+                format: int32
+                type: integer
               mode:
                 description: Mode represents how the collector should be deployed
                   (deployment, daemonset, statefulset or sidecar)

config/crd/bases/opentelemetry.io_opentelemetrycollectors.yaml

@@ -221,6 +221,10 @@ spec:
                   If MaxReplicas is set autoscaling is enabled.
                 format: int32
                 type: integer
+              minReplicas:
+                description: MinReplicas sets a lower bound to the autoscaling feature.
+                format: int32
+                type: integer
               mode:
                 description: Mode represents how the collector should be deployed
                   (deployment, daemonset, statefulset or sidecar)

docs/api.md

@@ -1455,6 +1455,15 @@ OpenTelemetryCollectorSpec defines the desired state of OpenTelemetryCollector.
             <i>Format</i>: int32<br/>
         </td>
         <td>false</td>
+      </tr><tr>
+        <td><b>minReplicas</b></td>
+        <td>integer</td>
+        <td>
+          MinReplicas sets a lower bound to the autoscaling feature.<br/>
+          <br/>
+            <i>Format</i>: int32<br/>
+        </td>
+        <td>false</td>
       </tr><tr>
         <td><b>mode</b></td>
         <td>enum</td>

hack/install-metrics-server.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# Install metrics-server on kind clusters for autoscale tests.  Note: This is not needed for minikube,
+# you can just add --addons "metrics-server" to the start command.
+kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
+kubectl patch deployment -n kube-system metrics-server --type "json" -p '[{"op": "add", "path": "/spec/template/spec/containers/0/args/-", "value": --kubelet-insecure-tls}]'
+kubectl wait --for=condition=available deployment/metrics-server -n kube-system  --timeout=5m

pkg/collector/horizontalpodautoscaler.go

@@ -35,17 +35,18 @@ func HorizontalPodAutoscaler(cfg config.Config, logger logr.Logger, otelcol v1al
 
 	return autoscalingv1.HorizontalPodAutoscaler{
 		ObjectMeta: metav1.ObjectMeta{
-			Name:        naming.Collector(otelcol),
+			Name:        naming.HorizontalPodAutoscaler(otelcol),
 			Namespace:   otelcol.Namespace,
 			Labels:      labels,
 			Annotations: annotations,
 		},
 		Spec: autoscalingv1.HorizontalPodAutoscalerSpec{
 			ScaleTargetRef: autoscalingv1.CrossVersionObjectReference{
-				APIVersion: "apps/v1",
-				Kind:       "Deployment",
-				Name:       naming.Collector(otelcol),
+				APIVersion: v1alpha1.GroupVersion.String(),
+				Kind:       "OpenTelemetryCollector",
+				Name:       naming.OpenTelemetryCollector(otelcol),
 			},
+
 			MinReplicas:                    otelcol.Spec.Replicas,
 			MaxReplicas:                    *otelcol.Spec.MaxReplicas,
 			TargetCPUUtilizationPercentage: &cpuTarget,

pkg/collector/reconcile/deployment.go

@@ -99,11 +99,6 @@ func expectedDeployments(ctx context.Context, params Params, expected []appsv1.D
 			updated.ObjectMeta.Labels[k] = v
 		}
 
-		if params.Instance.Spec.MaxReplicas != nil && desired.Labels["app.kubernetes.io/component"] == "opentelemetry-collector" {
-			currentReplicas := currentReplicasWithHPA(params.Instance.Spec, existing.Status.Replicas)
-			updated.Spec.Replicas = &currentReplicas
-		}
-
 		// Selector is an immutable field, if set, we cannot modify it otherwise we will face reconciliation error.
 		updated.Spec.Selector = existing.Spec.Selector.DeepCopy()
 

pkg/collector/reconcile/horizontalpodautoscaler.go

@@ -52,6 +52,7 @@ func HorizontalPodAutoscalers(ctx context.Context, params Params) error {
 }
 
 func expectedHorizontalPodAutoscalers(ctx context.Context, params Params, expected []autoscalingv1.HorizontalPodAutoscaler) error {
+	one := int32(1)
 	for _, obj := range expected {
 		desired := obj
 
@@ -81,9 +82,13 @@ func expectedHorizontalPodAutoscalers(ctx context.Context, params Params, expect
 		}
 
 		updated.OwnerReferences = desired.OwnerReferences
-		updated.Spec.MinReplicas = params.Instance.Spec.Replicas
 		if params.Instance.Spec.MaxReplicas != nil {
 			updated.Spec.MaxReplicas = *params.Instance.Spec.MaxReplicas
+			if params.Instance.Spec.MinReplicas != nil {
+				updated.Spec.MinReplicas = params.Instance.Spec.MinReplicas
+			} else {
+				updated.Spec.MinReplicas = &one
+			}
 		}
 
 		for k, v := range desired.Annotations {

pkg/collector/reconcile/horizontalpodautoscaler_test.go

@@ -52,6 +52,7 @@ func TestExpectedHPA(t *testing.T) {
 		maxReplicas := int32(3)
 		updateParms := paramsWithHPA()
 		updateParms.Instance.Spec.Replicas = &minReplicas
+		updateParms.Instance.Spec.Replicas = &minReplicas
 		updateParms.Instance.Spec.MaxReplicas = &maxReplicas
 		updatedHPA := collector.HorizontalPodAutoscaler(updateParms.Config, logger, updateParms.Instance)
 

pkg/naming/main.go

@@ -54,6 +54,16 @@ func Collector(otelcol v1alpha1.OpenTelemetryCollector) string {
 	return DNSName(Truncate("%s-collector", 63, otelcol.Name))
 }
 
+// HorizontalPodAutoscaler builds the autoscaler name based on the instance.
+func HorizontalPodAutoscaler(otelcol v1alpha1.OpenTelemetryCollector) string {
+	return DNSName(Truncate("%s-collector", 63, otelcol.Name))
+}
+
+// HorizontalPodAutoscaler builds the collector (deployment/daemonset) name based on the instance.
+func OpenTelemetryCollector(otelcol v1alpha1.OpenTelemetryCollector) string {
+	return DNSName(Truncate("%s", 63, otelcol.Name))
+}
+
 // TargetAllocator returns the TargetAllocator deployment resource name.
 func TargetAllocator(otelcol v1alpha1.OpenTelemetryCollector) string {
 	return DNSName(Truncate("%s-targetallocator", 63, otelcol.Name))

tests/e2e/autoscale/00-assert.yaml

@@ -0,0 +1,16 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: simplest-collector
+status:
+  readyReplicas: 1
+
+---
+apiVersion: autoscaling/v1
+kind: HorizontalPodAutoscaler
+metadata:
+  name: simplest-collector
+spec:
+  minReplicas: 1
+  maxReplicas: 2
+

tests/e2e/autoscale/00-install.yaml

@@ -0,0 +1,33 @@
+apiVersion: opentelemetry.io/v1alpha1
+kind: OpenTelemetryCollector
+metadata:
+  name: simplest
+spec:
+  replicas: 1
+  minReplicas: 1
+  maxReplicas: 2
+  resources:
+    limits:
+      cpu: 500m
+      memory: 128Mi
+    requests:
+      cpu: 5m
+      memory: 64Mi
+
+  config: |
+    receivers:
+      otlp:
+        protocols:
+          grpc:
+          http:
+    processors:
+
+    exporters:
+      logging:
+
+    service:
+      pipelines:
+        traces:
+          receivers: [otlp]
+          processors: []
+          exporters: [logging]

tests/e2e/autoscale/01-assert.yaml

@@ -0,0 +1,18 @@
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: tracegen
+status:
+  conditions:
+    - status: "True"
+      type: Complete
+
+---
+apiVersion: opentelemetry.io/v1alpha1
+kind: OpenTelemetryCollector
+
+metadata:
+  name: simplest
+status:
+  scale:
+    replicas: 2

tests/e2e/autoscale/01-install.yaml

@@ -0,0 +1,19 @@
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: tracegen
+spec:
+  template:
+    spec:
+      containers:
+        - name: tracegen
+          image: ghcr.io/open-telemetry/opentelemetry-collector-contrib/tracegen:latest
+          command:
+            - "./tracegen"
+          args:
+            - -otlp-endpoint=simplest-collector-headless:4317
+            - -otlp-insecure
+            - -duration=1m
+            - -workers=20
+      restartPolicy: Never
+  backoffLimit: 4