Add scale subresource status to the OpenTelemetryCollector CRD status

apis/v1alpha1/opentelemetrycollector_types.go

@@ -129,12 +129,31 @@ type OpenTelemetryTargetAllocator struct {
 	Image string `json:"image,omitempty"`
 }
 
+// ScaleSubresourceStatus defines the observed state of the OpenTelemetryCollector's
+// scale subresource.
+type ScaleSubresourceStatus struct {
+	// The total number non-terminated pods targeted by this
+	// OpenTelemetryCollector's deployment or statefulSet.
+	// +optional
+	Replicas int32 `json:"replicas,omitempty"`
+
+	// The selector used to match the OpenTelemetryCollector's
+	// deployment or statefulSet pods.
+	// +optional
+	Selector string `json:"selector,omitempty"`
+}
+
 // OpenTelemetryCollectorStatus defines the observed state of OpenTelemetryCollector.
 type OpenTelemetryCollectorStatus struct {
 	// Replicas is currently not being set and might be removed in the next version.
 	// +optional
+	// Deprecated: use "OpenTelemetryCollector.Status.Scale.Replicas" instead.
 	Replicas int32 `json:"replicas,omitempty"`
 
+	// Scale is the OpenTelemetryCollector's scale subresource status.
+	// +optional
+	Scale ScaleSubresourceStatus `json:"scale,omitempty"`
+
 	// Version of the managed OpenTelemetry Collector (operand)
 	// +optional
 	Version string `json:"version,omitempty"`
@@ -149,7 +168,7 @@ type OpenTelemetryCollectorStatus struct {
 // +kubebuilder:object:root=true
 // +kubebuilder:resource:shortName=otelcol;otelcols
 // +kubebuilder:subresource:status
-// +kubebuilder:subresource:scale:specpath=.spec.replicas,statuspath=.status.replicas
+// +kubebuilder:subresource:scale:specpath=.spec.replicas,statuspath=.status.scale.replicas,selectorpath=.status.scale.selector
 // +kubebuilder:printcolumn:name="Mode",type="string",JSONPath=".spec.mode",description="Deployment Mode"
 // +kubebuilder:printcolumn:name="Version",type="string",JSONPath=".status.version",description="OpenTelemetry Version"
 // +kubebuilder:printcolumn:name="Age",type="date",JSONPath=".metadata.creationTimestamp"

bundle/manifests/opentelemetry.io_opentelemetrycollectors.yaml

@@ -2567,10 +2567,25 @@ spec:
                 type: array
                 x-kubernetes-list-type: atomic
               replicas:
-                description: Replicas is currently not being set and might be removed
-                  in the next version.
+                description: 'Replicas is currently not being set and might be removed
+                  in the next version. Deprecated: use "OpenTelemetryCollector.Status.Scale.Replicas"
+                  instead.'
                 format: int32
                 type: integer
+              scale:
+                description: Scale is the OpenTelemetryCollector's scale subresource
+                  status.
+                properties:
+                  replicas:
+                    description: The total number non-terminated pods targeted by
+                      this OpenTelemetryCollector's deployment or statefulSet.
+                    format: int32
+                    type: integer
+                  selector:
+                    description: The selector used to match the OpenTelemetryCollector's
+                      deployment or statefulSet pods.
+                    type: string
+                type: object
               version:
                 description: Version of the managed OpenTelemetry Collector (operand)
                 type: string
@@ -2580,8 +2595,9 @@ spec:
     storage: true
     subresources:
       scale:
+        labelSelectorPath: .status.scale.selector
         specReplicasPath: .spec.replicas
-        statusReplicasPath: .status.replicas
+        statusReplicasPath: .status.scale.replicas
       status: {}
 status:
   acceptedNames:

config/crd/bases/opentelemetry.io_opentelemetrycollectors.yaml

@@ -2565,10 +2565,25 @@ spec:
                 type: array
                 x-kubernetes-list-type: atomic
               replicas:
-                description: Replicas is currently not being set and might be removed
-                  in the next version.
+                description: 'Replicas is currently not being set and might be removed
+                  in the next version. Deprecated: use "OpenTelemetryCollector.Status.Scale.Replicas"
+                  instead.'
                 format: int32
                 type: integer
+              scale:
+                description: Scale is the OpenTelemetryCollector's scale subresource
+                  status.
+                properties:
+                  replicas:
+                    description: The total number non-terminated pods targeted by
+                      this OpenTelemetryCollector's deployment or statefulSet.
+                    format: int32
+                    type: integer
+                  selector:
+                    description: The selector used to match the OpenTelemetryCollector's
+                      deployment or statefulSet pods.
+                    type: string
+                type: object
               version:
                 description: Version of the managed OpenTelemetry Collector (operand)
                 type: string
@@ -2578,8 +2593,9 @@ spec:
     storage: true
     subresources:
       scale:
+        labelSelectorPath: .status.scale.selector
         specReplicasPath: .spec.replicas
-        statusReplicasPath: .status.replicas
+        statusReplicasPath: .status.scale.replicas
       status: {}
 status:
   acceptedNames:

docs/api.md

@@ -6115,11 +6115,18 @@ OpenTelemetryCollectorStatus defines the observed state of OpenTelemetryCollecto
         <td><b>replicas</b></td>
         <td>integer</td>
         <td>
-          Replicas is currently not being set and might be removed in the next version.<br/>
+          Replicas is currently not being set and might be removed in the next version. Deprecated: use "OpenTelemetryCollector.Status.Scale.Replicas" instead.<br/>
           <br/>
             <i>Format</i>: int32<br/>
         </td>
         <td>false</td>
+      </tr><tr>
+        <td><b><a href="#opentelemetrycollectorstatusscale">scale</a></b></td>
+        <td>object</td>
+        <td>
+          Scale is the OpenTelemetryCollector's scale subresource status.<br/>
+        </td>
+        <td>false</td>
       </tr><tr>
         <td><b>version</b></td>
         <td>string</td>
@@ -6128,4 +6135,40 @@ OpenTelemetryCollectorStatus defines the observed state of OpenTelemetryCollecto
         </td>
         <td>false</td>
       </tr></tbody>
+</table>
+
+
+### OpenTelemetryCollector.status.scale
+<sup><sup>[↩ Parent](#opentelemetrycollectorstatus)</sup></sup>
+
+
+
+Scale is the OpenTelemetryCollector's scale subresource status.
+
+<table>
+    <thead>
+        <tr>
+            <th>Name</th>
+            <th>Type</th>
+            <th>Description</th>
+            <th>Required</th>
+        </tr>
+    </thead>
+    <tbody><tr>
+        <td><b>replicas</b></td>
+        <td>integer</td>
+        <td>
+          The total number non-terminated pods targeted by this OpenTelemetryCollector's deployment or statefulSet.<br/>
+          <br/>
+            <i>Format</i>: int32<br/>
+        </td>
+        <td>false</td>
+      </tr><tr>
+        <td><b>selector</b></td>
+        <td>string</td>
+        <td>
+          The selector used to match the OpenTelemetryCollector's deployment or statefulSet pods.<br/>
+        </td>
+        <td>false</td>
+      </tr></tbody>
 </table>

pkg/collector/reconcile/opentelemetry.go

@@ -19,28 +19,85 @@ import (
 	"context"
 	"fmt"
 
+	appsv1 "k8s.io/api/apps/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
+	"github.com/open-telemetry/opentelemetry-operator/apis/v1alpha1"
 	"github.com/open-telemetry/opentelemetry-operator/internal/version"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/collector"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/naming"
 )
 
 // Self updates this instance's self data. This should be the last item in the reconciliation, as it causes changes
 // making params.Instance obsolete. Default values should be set in the Defaulter webhook, this should only be used
 // for the Status, which can't be set by the defaulter.
 func Self(ctx context.Context, params Params) error {
-	if params.Instance.Status.Version != "" {
-		// a version is already set, let the upgrade mechanism take care of it!
-		return nil
+	changed := params.Instance
+
+	// this field is only changed for new instances: on existing instances this
+	// field is reconciled when the operator is first started, i.e. during
+	// the upgrade mechanism
+	if params.Instance.Status.Version == "" {
+		// a version is not set, otherwise let the upgrade mechanism take care of it!
+		changed.Status.Version = version.OpenTelemetryCollector()
 	}
 
-	changed := params.Instance
-	changed.Status.Version = version.OpenTelemetryCollector()
+	if err := updateScaleSubResourceStatus(ctx, params.Client, &changed); err != nil {
+		return fmt.Errorf("failed to update the scale subresource status for the OpenTelemetry CR: %w", err)
+	}
 
-	// this is only a change for new instances: existing instances are reconciled when the operator is first started
 	statusPatch := client.MergeFrom(&params.Instance)
 	if err := params.Client.Status().Patch(ctx, &changed, statusPatch); err != nil {
 		return fmt.Errorf("failed to apply status changes to the OpenTelemetry CR: %w", err)
 	}
 
 	return nil
 }
+
+func updateScaleSubResourceStatus(ctx context.Context, cli client.Client, changed *v1alpha1.OpenTelemetryCollector) error {
+	mode := changed.Spec.Mode
+	if mode != v1alpha1.ModeDeployment && mode != v1alpha1.ModeStatefulSet {
+		changed.Status.Scale.Replicas = 0
+		changed.Status.Scale.Selector = ""
+
+		return nil
+	}
+
+	name := naming.Collector(*changed)
+
+	// Set the scale selector
+	labels := collector.Labels(*changed)
+	labels["app.kubernetes.io/name"] = name
+	selector, err := metav1.LabelSelectorAsSelector(&metav1.LabelSelector{MatchLabels: labels})
+	if err != nil {
+		return fmt.Errorf("failed to get selector for labelSelector: %w", err)
+	}
+	changed.Status.Scale.Selector = selector.String()
+
+	// Set the scale replicas
+	objKey := client.ObjectKey{
+		Namespace: changed.GetNamespace(),
+		Name:      naming.Collector(*changed),
+	}
+
+	var replicas int32
+	switch mode { // nolint:exhaustive
+	case v1alpha1.ModeDeployment:
+		obj := &appsv1.Deployment{}
+		if err := cli.Get(ctx, objKey, obj); err != nil {
+			return fmt.Errorf("failed to get deployment status.replicas: %w", err)
+		}
+		replicas = obj.Status.Replicas
+
+	case v1alpha1.ModeStatefulSet:
+		obj := &appsv1.StatefulSet{}
+		if err := cli.Get(ctx, objKey, obj); err != nil {
+			return fmt.Errorf("failed to get statefulSet status.replicas: %w", err)
+		}
+		replicas = obj.Status.Replicas
+	}
+	changed.Status.Scale.Replicas = replicas
+
+	return nil
+}