feat(controller): ImpWarmPool — maintain pool of snapshot-booted VMs

Author: syscod3

cmd/operator/main.go

@@ -178,6 +178,14 @@ func main() {
 		os.Exit(1)
 	}
 
+	if err = (&controller.ImpWarmPoolReconciler{
+		Client: mgr.GetClient(),
+		Scheme: mgr.GetScheme(),
+	}).SetupWithManager(mgr); err != nil {
+		setupLog.Error(err, "unable to create controller", "controller", "ImpWarmPool")
+		os.Exit(1)
+	}
+
 	if err = builder.WebhookManagedBy(mgr, &impv1alpha1.ImpVM{}).
 		WithDefaulter(&webhookv1alpha1.ImpVMWebhook{}).
 		WithValidator(&webhookv1alpha1.ImpVMWebhook{}).

internal/controller/impwarmpool_controller.go

@@ -0,0 +1,187 @@
+/*
+Copyright 2026.
+
+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 controller
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+
+	impv1alpha1 "github.com/syscode-labs/imp/api/v1alpha1"
+)
+
+// ImpWarmPoolReconciler reconciles ImpWarmPool objects.
+type ImpWarmPoolReconciler struct {
+	client.Client
+	Scheme *runtime.Scheme
+}
+
+// +kubebuilder:rbac:groups=imp.dev,resources=impwarmpools,verbs=get;list;watch;create;update;patch;delete
+// +kubebuilder:rbac:groups=imp.dev,resources=impwarmpools/status,verbs=get;update;patch
+// +kubebuilder:rbac:groups=imp.dev,resources=impwarmpools/finalizers,verbs=update
+// +kubebuilder:rbac:groups=imp.dev,resources=impvmsnapshots,verbs=get;list;watch
+// +kubebuilder:rbac:groups=imp.dev,resources=impvmtemplates,verbs=get;list;watch
+// +kubebuilder:rbac:groups=imp.dev,resources=impvms,verbs=get;list;watch;create
+
+func (r *ImpWarmPoolReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+	log := logf.FromContext(ctx)
+
+	pool := &impv1alpha1.ImpWarmPool{}
+	if err := r.Get(ctx, req.NamespacedName, pool); err != nil {
+		return ctrl.Result{}, client.IgnoreNotFound(err)
+	}
+
+	// Fetch the ImpVMSnapshot named by spec.snapshotRef.
+	snap := &impv1alpha1.ImpVMSnapshot{}
+	if err := r.Get(ctx, client.ObjectKey{
+		Namespace: pool.Namespace,
+		Name:      pool.Spec.SnapshotRef,
+	}, snap); err != nil {
+		if apierrors.IsNotFound(err) {
+			log.Info("ImpVMSnapshot not found, requeueing", "snapshotRef", pool.Spec.SnapshotRef)
+			return ctrl.Result{RequeueAfter: 30 * time.Second}, nil
+		}
+		return ctrl.Result{}, err
+	}
+
+	// Pool stays idle until a base snapshot has been elected.
+	baseSnapshot := snap.Status.BaseSnapshot
+	if baseSnapshot == "" {
+		log.Info("no base snapshot elected yet, pool idle", "pool", pool.Name, "snapshotRef", pool.Spec.SnapshotRef)
+		return ctrl.Result{RequeueAfter: 30 * time.Second}, nil
+	}
+
+	// Fetch the ImpVMTemplate to build VM specs.
+	tpl := &impv1alpha1.ImpVMTemplate{}
+	if err := r.Get(ctx, client.ObjectKey{
+		Namespace: pool.Namespace,
+		Name:      pool.Spec.TemplateName,
+	}, tpl); err != nil {
+		if apierrors.IsNotFound(err) {
+			log.Info("ImpVMTemplate not found, requeueing", "templateName", pool.Spec.TemplateName)
+			return ctrl.Result{RequeueAfter: 30 * time.Second}, nil
+		}
+		return ctrl.Result{}, err
+	}
+
+	// List pool members: ImpVMs labeled with this pool name.
+	vmList := &impv1alpha1.ImpVMList{}
+	if err := r.List(ctx, vmList,
+		client.InNamespace(pool.Namespace),
+		client.MatchingLabels{impv1alpha1.LabelWarmPool: pool.Name},
+	); err != nil {
+		return ctrl.Result{}, err
+	}
+
+	// Count ready (Running) and active (not Failed/RetryExhausted) members.
+	var readyCount, activeCount int32
+	for i := range vmList.Items {
+		phase := vmList.Items[i].Status.Phase
+		switch phase {
+		case impv1alpha1.VMPhaseRunning:
+			readyCount++
+			activeCount++
+		case impv1alpha1.VMPhaseFailed, impv1alpha1.VMPhaseRetryExhausted, impv1alpha1.VMPhaseSucceeded:
+			// terminal — do not count as active
+		default:
+			// Pending, Scheduled, Starting, Terminating — count as active
+			activeCount++
+		}
+	}
+
+	// Create missing VMs to reach spec.size.
+	toCreate := pool.Spec.Size - activeCount
+	for i := int32(0); i < toCreate; i++ {
+		if err := r.createPoolMember(ctx, pool, tpl, baseSnapshot); err != nil {
+			return ctrl.Result{}, err
+		}
+	}
+	if toCreate > 0 {
+		log.Info("created pool members", "pool", pool.Name, "count", toCreate, "baseSnapshot", baseSnapshot)
+	}
+
+	// Patch status.readyCount.
+	base := pool.DeepCopy()
+	pool.Status.ReadyCount = readyCount
+	if err := r.Status().Patch(ctx, pool, client.MergeFrom(base)); err != nil {
+		return ctrl.Result{}, err
+	}
+
+	return ctrl.Result{RequeueAfter: 30 * time.Second}, nil
+}
+
+// createPoolMember creates a single ImpVM pool member.
+func (r *ImpWarmPoolReconciler) createPoolMember(
+	ctx context.Context,
+	pool *impv1alpha1.ImpWarmPool,
+	tpl *impv1alpha1.ImpVMTemplate,
+	baseSnapshot string,
+) error {
+	vmName := fmt.Sprintf("%s-%s", pool.Name, time.Now().UTC().Format("20060102-150405-000000"))
+
+	vm := &impv1alpha1.ImpVM{
+		ObjectMeta: metav1.ObjectMeta{
+			GenerateName: pool.Name + "-",
+			Namespace:    pool.Namespace,
+			Labels: map[string]string{
+				impv1alpha1.LabelWarmPool: pool.Name,
+			},
+		},
+		Spec: impv1alpha1.ImpVMSpec{
+			ClassRef:    &tpl.Spec.ClassRef,
+			Image:       tpl.Spec.Image,
+			SnapshotRef: baseSnapshot,
+		},
+	}
+	_ = vmName // GenerateName is used instead; vmName would conflict on fast loops
+
+	if tpl.Spec.NetworkRef != nil {
+		vm.Spec.NetworkRef = tpl.Spec.NetworkRef
+	}
+	if tpl.Spec.RestartPolicy != nil {
+		vm.Spec.RestartPolicy = tpl.Spec.RestartPolicy
+	}
+	if tpl.Spec.Probes != nil {
+		vm.Spec.Probes = tpl.Spec.Probes
+	}
+	if tpl.Spec.GuestAgent != nil {
+		vm.Spec.GuestAgent = tpl.Spec.GuestAgent
+	}
+	if tpl.Spec.NetworkGroup != "" {
+		vm.Spec.NetworkGroup = tpl.Spec.NetworkGroup
+	}
+
+	if err := ctrl.SetControllerReference(pool, vm, r.Scheme); err != nil {
+		return err
+	}
+
+	return r.Create(ctx, vm)
+}
+
+func (r *ImpWarmPoolReconciler) SetupWithManager(mgr ctrl.Manager) error {
+	return ctrl.NewControllerManagedBy(mgr).
+		For(&impv1alpha1.ImpWarmPool{}).
+		Owns(&impv1alpha1.ImpVM{}).
+		Complete(r)
+}