[node operator] AutoscalingStrategy controller impl

Signed-off-by: Malte Poll <mp@edgeless.systems>

operators/constellation-node-operator/config/rbac/role.yaml

@@ -5,6 +5,17 @@ metadata:
   creationTimestamp: null
   name: manager-role
 rules:
+- apiGroups:
+  - apps
+  resources:
+  - deployments
+  verbs:
+  - create
+  - delete
+  - get
+  - list
+  - update
+  - watch
 - apiGroups:
   - update.edgeless.systems
   resources:

operators/constellation-node-operator/controllers/autoscalingstrategy_controller.go

@@ -4,7 +4,10 @@ package controllers
 import (
 	"context"
 
+	appsv1 "k8s.io/api/apps/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/client-go/util/retry"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/log"
@@ -21,20 +24,51 @@ type AutoscalingStrategyReconciler struct {
 //+kubebuilder:rbac:groups=update.edgeless.systems,resources=autoscalingstrategies,verbs=get;list;watch;create;update;patch;delete
 //+kubebuilder:rbac:groups=update.edgeless.systems,resources=autoscalingstrategies/status,verbs=get;update;patch
 //+kubebuilder:rbac:groups=update.edgeless.systems,resources=autoscalingstrategies/finalizers,verbs=update
+//+kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;delete
 
-// Reconcile is part of the main kubernetes reconciliation loop which aims to
+// Reconcile enabled or disables the cluster-autoscaler based on the AutoscalingStrategy spec
-// move the current state of the cluster closer to the desired state.
+// by modifying the replicas of the Deployment.
-// TODO(user): Modify the Reconcile function to compare the state specified by
-// the AutoscalingStrategy object against the actual cluster state, and then
-// perform operations to make the cluster state reflect the state specified by
-// the user.
-//
-// For more details, check Reconcile and its Result here:
-// - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.11.2/pkg/reconcile
 func (r *AutoscalingStrategyReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
-	_ = log.FromContext(ctx)
+	logr := log.FromContext(ctx)
 
-	// TODO(user): your logic here
+	var desiredAutoscalingStrategy updatev1alpha1.AutoscalingStrategy
+	if err := r.Get(ctx, req.NamespacedName, &desiredAutoscalingStrategy); err != nil {
+		logr.Error(err, "Unable to fetch AutoscalingStrategy")
+		return ctrl.Result{}, client.IgnoreNotFound(err)
+	}
+	var expectedReplicas int32
+	if desiredAutoscalingStrategy.Spec.Enabled {
+		expectedReplicas = 1
+	}
+
+	var autoscalerDeployment appsv1.Deployment
+	if err := r.Get(ctx, client.ObjectKey{Namespace: desiredAutoscalingStrategy.Spec.DeploymentNamespace, Name: desiredAutoscalingStrategy.Spec.DeploymentName}, &autoscalerDeployment); err != nil {
+		logr.Error(err, "Unable to fetch autoscaler Deployment")
+		return ctrl.Result{}, client.IgnoreNotFound(err)
+	}
+
+	if autoscalerDeployment.Spec.Replicas == nil || *autoscalerDeployment.Spec.Replicas == 0 {
+		desiredAutoscalingStrategy.Status.Enabled = false
+		desiredAutoscalingStrategy.Status.Replicas = 0
+	} else {
+		desiredAutoscalingStrategy.Status.Enabled = true
+		desiredAutoscalingStrategy.Status.Replicas = *autoscalerDeployment.Spec.Replicas
+	}
+
+	if err := r.tryUpdateStatus(ctx, req.NamespacedName, desiredAutoscalingStrategy.Status); err != nil {
+		logr.Error(err, "Unable to update AutoscalingStrategy status")
+		return ctrl.Result{}, err
+	}
+
+	if autoscalerDeployment.Spec.Replicas == nil || *autoscalerDeployment.Spec.Replicas != expectedReplicas {
+		logr.Info("Updating autoscaling replicas", "expectedReplicas", expectedReplicas)
+		autoscalerDeployment.Spec.Replicas = &expectedReplicas
+		if err := r.Update(ctx, &autoscalerDeployment); err != nil {
+			logr.Error(err, "Unable to update autoscaler Deployment")
+			return ctrl.Result{}, err
+		}
+		return ctrl.Result{Requeue: true}, nil
+	}
 
 	return ctrl.Result{}, nil
 }
@@ -45,3 +79,18 @@ func (r *AutoscalingStrategyReconciler) SetupWithManager(mgr ctrl.Manager) error
 		For(&updatev1alpha1.AutoscalingStrategy{}).
 		Complete(r)
 }
+
+// tryUpdateStatus attempts to update the AutoscalingStrategy status field in a retry loop.
+func (r *AutoscalingStrategyReconciler) tryUpdateStatus(ctx context.Context, name types.NamespacedName, status updatev1alpha1.AutoscalingStrategyStatus) error {
+	return retry.RetryOnConflict(retry.DefaultRetry, func() error {
+		var autoscalingStrategy updatev1alpha1.AutoscalingStrategy
+		if err := r.Get(ctx, name, &autoscalingStrategy); err != nil {
+			return err
+		}
+		autoscalingStrategy.Status = *status.DeepCopy()
+		if err := r.Status().Update(ctx, &autoscalingStrategy); err != nil {
+			return err
+		}
+		return nil
+	})
+}