✨ Add MachinePool workers support in ClusterClass

api/v1beta1/condition_consts.go

@@ -299,6 +299,19 @@ const (
 	// not yet completed because the upgrade for at least one of the MachineDeployments has been deferred.
 	TopologyReconciledMachineDeploymentsUpgradeDeferredReason = "MachineDeploymentsUpgradeDeferred"
 
+	// TopologyReconciledMachinePoolsUpgradePendingReason (Severity=Info) documents reconciliation of a Cluster topology
+	// not yet completed because at least one of the MachinePools is not yet updated to match the desired topology spec.
+	TopologyReconciledMachinePoolsUpgradePendingReason = "MachinePoolsUpgradePending"
+
+	// TopologyReconciledMachinePoolsCreatePendingReason (Severity=Info) documents reconciliation of a Cluster topology
+	// not yet completed because at least one of the MachinePools is yet to be created.
+	// This generally happens because new MachinePool creations are held off while the ControlPlane is not stable.
+	TopologyReconciledMachinePoolsCreatePendingReason = "MachinePoolsCreatePending"
+
+	// TopologyReconciledMachinePoolsUpgradeDeferredReason (Severity=Info) documents reconciliation of a Cluster topology
+	// not yet completed because the upgrade for at least one of the MachinePools has been deferred.
+	TopologyReconciledMachinePoolsUpgradeDeferredReason = "MachinePoolsUpgradeDeferred"
+
 	// TopologyReconciledHookBlockingReason (Severity=Info) documents reconciliation of a Cluster topology
 	// not yet completed because at least one of the lifecycle hooks is blocking.
 	TopologyReconciledHookBlockingReason = "LifecycleHookBlocking"

cmd/clusterctl/client/cluster/topology.go

@@ -802,6 +802,17 @@ func clusterClassUsesTemplate(cc *clusterv1.ClusterClass, templateRef *corev1.Ob
 		}
 	}
 
+	for _, mpClass := range cc.Spec.Workers.MachinePools {
+		// Check the bootstrap ref
+		if equalRef(mpClass.Template.Bootstrap.Ref, templateRef) {
+			return true
+		}
+		// Check the infrastructure ref.
+		if equalRef(mpClass.Template.Infrastructure.Ref, templateRef) {
+			return true
+		}
+	}
+
 	return false
 }
 

config/rbac/role.yaml

@@ -187,6 +187,18 @@ rules:
   - patch
   - update
   - watch
+- apiGroups:
+  - cluster.x-k8s.io
+  resources:
+  - machinepools
+  verbs:
+  - create
+  - delete
+  - get
+  - list
+  - patch
+  - update
+  - watch
 - apiGroups:
   - cluster.x-k8s.io
   resources:

controllers/alias.go

@@ -143,7 +143,8 @@ func (r *MachineHealthCheckReconciler) SetupWithManager(ctx context.Context, mgr
 
 // ClusterTopologyReconciler reconciles a managed topology for a Cluster object.
 type ClusterTopologyReconciler struct {
-	Client client.Client
+	Client  client.Client
+	Tracker *remote.ClusterCacheTracker
 	// APIReader is used to list MachineSets directly via the API server to avoid
 	// race conditions caused by an outdated cache.
 	APIReader client.Reader
@@ -162,6 +163,7 @@ func (r *ClusterTopologyReconciler) SetupWithManager(ctx context.Context, mgr ct
 	return (&clustertopologycontroller.Reconciler{
 		Client:                    r.Client,
 		APIReader:                 r.APIReader,
+		Tracker:                   r.Tracker,
 		RuntimeClient:             r.RuntimeClient,
 		UnstructuredCachingClient: r.UnstructuredCachingClient,
 		WatchFilterValue:          r.WatchFilterValue,

internal/controllers/clusterclass/clusterclass_controller.go

@@ -169,11 +169,20 @@ func (r *Reconciler) reconcileExternalReferences(ctx context.Context, clusterCla
 		}
 	}
 
+	for _, mpClass := range clusterClass.Spec.Workers.MachinePools {
+		if mpClass.Template.Bootstrap.Ref != nil {
+			refs = append(refs, mpClass.Template.Bootstrap.Ref)
+		}
+		if mpClass.Template.Infrastructure.Ref != nil {
+			refs = append(refs, mpClass.Template.Infrastructure.Ref)
+		}
+	}
+
 	// Ensure all referenced objects are owned by the ClusterClass.
 	// Nb. Some external objects can be referenced multiple times in the ClusterClass,
 	// but we only want to set the owner reference once per unique external object.
 	// For example the same KubeadmConfigTemplate could be referenced in multiple MachineDeployment
-	// classes.
+	// or MachinePool classes.
 	errs := []error{}
 	reconciledRefs := sets.Set[string]{}
 	outdatedRefs := map[*corev1.ObjectReference]*corev1.ObjectReference{}

internal/controllers/topology/cluster/blueprint.go

@@ -34,6 +34,7 @@ func (r *Reconciler) getBlueprint(ctx context.Context, cluster *clusterv1.Cluste
 		Topology:           cluster.Spec.Topology,
 		ClusterClass:       clusterClass,
 		MachineDeployments: map[string]*scope.MachineDeploymentBlueprint{},
+		MachinePools:       map[string]*scope.MachinePoolBlueprint{},
 	}
 
 	var err error
@@ -82,7 +83,7 @@ func (r *Reconciler) getBlueprint(ctx context.Context, cluster *clusterv1.Cluste
 		// Get the bootstrap machine template.
 		machineDeploymentBlueprint.BootstrapTemplate, err = r.getReference(ctx, machineDeploymentClass.Template.Bootstrap.Ref)
 		if err != nil {
-			return nil, errors.Wrapf(err, "failed to get bootstrap machine template for %s, MachineDeployment class %q", tlog.KObj{Obj: blueprint.ClusterClass}, machineDeploymentClass.Class)
+			return nil, errors.Wrapf(err, "failed to get bootstrap config template for %s, MachineDeployment class %q", tlog.KObj{Obj: blueprint.ClusterClass}, machineDeploymentClass.Class)
 		}
 
 		// If the machineDeploymentClass defines a MachineHealthCheck add it to the blueprint.
@@ -92,5 +93,30 @@ func (r *Reconciler) getBlueprint(ctx context.Context, cluster *clusterv1.Cluste
 		blueprint.MachineDeployments[machineDeploymentClass.Class] = machineDeploymentBlueprint
 	}
 
+	// Loop over the machine pool classes in ClusterClass
+	// and fetch the related templates.
+	for _, machinePoolClass := range blueprint.ClusterClass.Spec.Workers.MachinePools {
+		machinePoolBlueprint := &scope.MachinePoolBlueprint{}
+
+		// Make sure to copy the metadata from the blueprint, which is later layered
+		// with the additional metadata defined in the Cluster's topology section
+		// for the MachinePool that is created or updated.
+		machinePoolClass.Template.Metadata.DeepCopyInto(&machinePoolBlueprint.Metadata)
+
+		// Get the InfrastructureMachinePoolTemplate.
+		machinePoolBlueprint.InfrastructureMachinePoolTemplate, err = r.getReference(ctx, machinePoolClass.Template.Infrastructure.Ref)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to get InfrastructureMachinePoolTemplate for %s, MachinePool class %q", tlog.KObj{Obj: blueprint.ClusterClass}, machinePoolClass.Class)
+		}
+
+		// Get the bootstrap config.
+		machinePoolBlueprint.BootstrapTemplate, err = r.getReference(ctx, machinePoolClass.Template.Bootstrap.Ref)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to get bootstrap config for %s, MachinePool class %q", tlog.KObj{Obj: blueprint.ClusterClass}, machinePoolClass.Class)
+		}
+
+		blueprint.MachinePools[machinePoolClass.Class] = machinePoolBlueprint
+	}
+
 	return blueprint, nil
 }

internal/controllers/topology/cluster/cluster_controller.go

@@ -36,6 +36,8 @@ import (
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
 	"sigs.k8s.io/cluster-api/api/v1beta1/index"
 	"sigs.k8s.io/cluster-api/controllers/external"
+	"sigs.k8s.io/cluster-api/controllers/remote"
+	expv1 "sigs.k8s.io/cluster-api/exp/api/v1beta1"
 	runtimecatalog "sigs.k8s.io/cluster-api/exp/runtime/catalog"
 	runtimehooksv1 "sigs.k8s.io/cluster-api/exp/runtime/hooks/api/v1alpha1"
 	"sigs.k8s.io/cluster-api/feature"
@@ -57,13 +59,15 @@ import (
 // +kubebuilder:rbac:groups=cluster.x-k8s.io,resources=clusters;clusters/status,verbs=get;list;watch;create;update;patch;delete
 // +kubebuilder:rbac:groups=cluster.x-k8s.io,resources=clusterclasses,verbs=get;list;watch;create;update;patch;delete
 // +kubebuilder:rbac:groups=cluster.x-k8s.io,resources=machinedeployments,verbs=get;list;watch;create;update;patch;delete
+// +kubebuilder:rbac:groups=cluster.x-k8s.io,resources=machinepools,verbs=get;list;watch;create;update;patch;delete
 // +kubebuilder:rbac:groups=cluster.x-k8s.io,resources=machinehealthchecks,verbs=get;list;watch;create;update;patch;delete
 // +kubebuilder:rbac:groups=apiextensions.k8s.io,resources=customresourcedefinitions,verbs=get;list;watch
 // +kubebuilder:rbac:groups=core,resources=secrets,verbs=get;create;delete
 
 // Reconciler reconciles a managed topology for a Cluster object.
 type Reconciler struct {
-	Client client.Client
+	Client  client.Client
+	Tracker *remote.ClusterCacheTracker
 	// APIReader is used to list MachineSets directly via the API server to avoid
 	// race conditions caused by an outdated cache.
 	APIReader client.Reader
@@ -103,6 +107,12 @@ func (r *Reconciler) SetupWithManager(ctx context.Context, mgr ctrl.Manager, opt
 			// Only trigger Cluster reconciliation if the MachineDeployment is topology owned.
 			builder.WithPredicates(predicates.ResourceIsTopologyOwned(ctrl.LoggerFrom(ctx))),
 		).
+		Watches(
+			&expv1.MachinePool{},
+			handler.EnqueueRequestsFromMapFunc(r.machinePoolToCluster),
+			// Only trigger Cluster reconciliation if the MachinePool is topology owned.
+			builder.WithPredicates(predicates.ResourceIsTopologyOwned(ctrl.LoggerFrom(ctx))),
+		).
 		WithOptions(options).
 		WithEventFilter(predicates.ResourceNotPausedAndHasFilterLabel(ctrl.LoggerFrom(ctx), r.WatchFilterValue)).
 		Build(r)
@@ -193,7 +203,16 @@ func (r *Reconciler) Reconcile(ctx context.Context, req ctrl.Request) (_ ctrl.Re
 	}
 
 	// Handle normal reconciliation loop.
-	return r.reconcile(ctx, s)
+	result, err := r.reconcile(ctx, s)
+	if err != nil {
+		// Requeue if the reconcile failed because the ClusterCacheTracker was locked for
+		// the current cluster because of concurrent access.
+		if errors.Is(err, remote.ErrClusterLocked) {
+			log.V(5).Info("Requeuing because another worker has the lock on the ClusterCacheTracker")
+			return ctrl.Result{Requeue: true}, nil
+		}
+	}
+	return result, err
 }
 
 // reconcile handles cluster reconciliation.
@@ -360,6 +379,25 @@ func (r *Reconciler) machineDeploymentToCluster(_ context.Context, o client.Obje
 	}}
 }
 
+// machinePoolToCluster is a handler.ToRequestsFunc to be used to enqueue requests for reconciliation
+// for Cluster to update when one of its own MachinePools gets updated.
+func (r *Reconciler) machinePoolToCluster(_ context.Context, o client.Object) []ctrl.Request {
+	mp, ok := o.(*expv1.MachinePool)
+	if !ok {
+		panic(fmt.Sprintf("Expected a MachinePool but got a %T", o))
+	}
+	if mp.Spec.ClusterName == "" {
+		return nil
+	}
+
+	return []ctrl.Request{{
+		NamespacedName: types.NamespacedName{
+			Namespace: mp.Namespace,
+			Name:      mp.Spec.ClusterName,
+		},
+	}}
+}
+
 func (r *Reconciler) reconcileDelete(ctx context.Context, cluster *clusterv1.Cluster) (ctrl.Result, error) {
 	// Call the BeforeClusterDelete hook if the 'ok-to-delete' annotation is not set
 	// and add the annotation to the cluster after receiving a successful non-blocking response.

internal/controllers/topology/cluster/conditions.go

@@ -143,6 +143,23 @@ func (r *Reconciler) reconcileTopologyReconciledCondition(s *scope.Scope, cluste
 				s.Blueprint.Topology.Version,
 			)
 			reason = clusterv1.TopologyReconciledMachineDeploymentsUpgradeDeferredReason
+		case s.UpgradeTracker.MachinePools.IsAnyPendingUpgrade():
+			fmt.Fprintf(msgBuilder, "MachinePool(s) %s rollout and upgrade to version %s on hold.",
+				computeNameList(s.UpgradeTracker.MachinePools.PendingUpgradeNames()),
+				s.Blueprint.Topology.Version,
+			)
+			reason = clusterv1.TopologyReconciledMachinePoolsUpgradePendingReason
+		case s.UpgradeTracker.MachinePools.IsAnyPendingCreate():
+			fmt.Fprintf(msgBuilder, "MachinePool(s) for Topologies %s creation on hold.",
+				computeNameList(s.UpgradeTracker.MachinePools.PendingCreateTopologyNames()),
+			)
+			reason = clusterv1.TopologyReconciledMachinePoolsCreatePendingReason
+		case s.UpgradeTracker.MachinePools.DeferredUpgrade():
+			fmt.Fprintf(msgBuilder, "MachinePool(s) %s rollout and upgrade to version %s deferred.",
+				computeNameList(s.UpgradeTracker.MachinePools.DeferredUpgradeNames()),
+				s.Blueprint.Topology.Version,
+			)
+			reason = clusterv1.TopologyReconciledMachinePoolsUpgradeDeferredReason
 		}
 
 		switch {