Added /scale subresource to TemporalWorkerDeployment CRD

- Enables KEDA and Kubernetes HPA to directly scale the custom resource
- Controller aggregates replica counts in status.replicas
- Controller sets label selector in status.selector for pod discovery
- CRD properly configured with /scale subresource
- Tested with 1000-workflow load test demonstrating successful scaling

Author: dezlitz

api/v1alpha1/worker_types.go

@@ -108,6 +108,17 @@ type TemporalWorkerDeploymentStatus struct {
 	// so it's generally not a good idea to read from the status of the root object.
 	// Instead, you should reconstruct it every run.
 
+	// Replicas is the total number of non-terminated pods targeted by this TemporalWorkerDeployment.
+	// This is used by the /scale subresource to report current replica count to HPA/KEDA.
+	// +optional
+	Replicas int32 `json:"replicas,omitempty"`
+
+	// Selector is the label selector for pods managed by this TemporalWorkerDeployment.
+	// This is used by the /scale subresource to allow HPA/KEDA to discover pods.
+	// Format: "app.kubernetes.io/name=<name>"
+	// +optional
+	Selector string `json:"selector,omitempty"`
+
 	// TargetVersion is the desired next version. If TargetVersion.Deployment is nil,
 	// then the controller should create it. If not nil, the controller should
 	// wait for it to become healthy and then move it to the CurrentVersion.
@@ -348,7 +359,9 @@ type ManualRolloutStrategy struct{}
 
 //+kubebuilder:object:root=true
 //+kubebuilder:subresource:status
+//+kubebuilder:subresource:scale:specpath=.spec.replicas,statuspath=.status.replicas,selectorpath=.status.selector
 // +kubebuilder:resource:shortName=twd;twdeployment;tworkerdeployment
+//+kubebuilder:printcolumn:name="Replicas",type="integer",JSONPath=".status.replicas",description="Current replicas"
 //+kubebuilder:printcolumn:name="Current",type="string",JSONPath=".status.currentVersion.buildID",description="Current build ID"
 //+kubebuilder:printcolumn:name="Target",type="string",JSONPath=".status.targetVersion.buildID",description="Target build ID"
 //+kubebuilder:printcolumn:name="Ramp %",type="number",JSONPath=".status.targetVersion.rampPercentage",description="Ramp percentage"

helm/temporal-worker-controller/Chart.yaml

@@ -2,5 +2,5 @@ apiVersion: v2
 name: temporal-worker-controller
 description: A Helm chart for the Temporal Worker Controller
 type: application
-version: 0.11.0
-appVersion: 1.1.1
+version: 0.10.0
+appVersion: 1.1.0

helm/temporal-worker-controller/crds/temporal.io_temporalworkerdeployments.yaml

@@ -19,6 +19,10 @@ spec:
   scope: Namespaced
   versions:
   - additionalPrinterColumns:
+    - description: Current replicas
+      jsonPath: .status.replicas
+      name: Replicas
+      type: integer
     - description: Current build ID
       jsonPath: .status.currentVersion.buildID
       name: Current
@@ -64,7 +68,6 @@ spec:
                   gate:
                     properties:
                       input:
-                        type: object
                         x-kubernetes-preserve-unknown-fields: true
                       inputFrom:
                         properties:
@@ -73,25 +76,27 @@ spec:
                               key:
                                 type: string
                               name:
+                                default: ""
                                 type: string
                               optional:
                                 type: boolean
                             required:
                             - key
-                            - name
                             type: object
+                            x-kubernetes-map-type: atomic
                           secretKeyRef:
                             properties:
                               key:
                                 type: string
                               name:
+                                default: ""
                                 type: string
                               optional:
                                 type: boolean
                             required:
                             - key
-                            - name
                             type: object
+                            x-kubernetes-map-type: atomic
                         type: object
                       workflowType:
                         type: string
@@ -4057,6 +4062,11 @@ spec:
                 type: array
               lastModifierIdentity:
                 type: string
+              replicas:
+                format: int32
+                type: integer
+              selector:
+                type: string
               targetVersion:
                 properties:
                   buildID:
@@ -4141,4 +4151,8 @@ spec:
     served: true
     storage: true
     subresources:
+      scale:
+        labelSelectorPath: .status.selector
+        specReplicasPath: .spec.replicas
+        statusReplicasPath: .status.replicas
       status: {}

internal/controller/state_mapper.go

@@ -5,6 +5,8 @@
 package controller
 
 import (
+	"strings"
+
 	"github.com/temporalio/temporal-worker-controller/api/v1alpha1"
 	"github.com/temporalio/temporal-worker-controller/internal/k8s"
 	"github.com/temporalio/temporal-worker-controller/internal/temporal"
@@ -35,6 +37,25 @@ func (m *stateMapper) mapToStatus(targetBuildID string) *v1alpha1.TemporalWorker
 
 	status.LastModifierIdentity = m.temporalState.LastModifierIdentity
 
+	// Compute total replicas from all managed deployments for /scale subresource
+	// This allows HPA/KEDA to query the current replica count
+	var totalReplicas int32
+	for _, deployment := range m.k8sState.Deployments {
+		if deployment.Status.Replicas > 0 {
+			totalReplicas += deployment.Status.Replicas
+		}
+	}
+	status.Replicas = totalReplicas
+
+	// Set label selector for /scale subresource - allows HPA/KEDA to discover pods
+	// Uses app.kubernetes.io/name label since all managed pods share this label
+	// Note: workerDeploymentName is namespace/name, but we only want the name part for labels
+	name := m.workerDeploymentName
+	if idx := strings.LastIndex(name, "/"); idx >= 0 {
+		name = name[idx+1:]
+	}
+	status.Selector = "app.kubernetes.io/name=" + name
+
 	// Get build IDs directly from temporal state
 	currentBuildID := m.temporalState.CurrentBuildID
 	rampingBuildID := m.temporalState.RampingBuildID