🌱 Compute desired Cluster and its referenced objects for a managed topology

api/v1alpha4/common_types.go

@@ -26,6 +26,9 @@ const (
 	// external objects(bootstrap and infrastructure providers).
 	ClusterLabelName = "cluster.x-k8s.io/cluster-name"
 
+	// ClusterTopologyLabelName is the label set on all the object which are managed as part of a ClusterTopology.
+	ClusterTopologyLabelName = "cluster.x-k8s.io/topology"
+
 	// ProviderLabelName is the label set on components in the provider manifest.
 	// This label allows to easily identify all the components belonging to a provider; the clusterctl
 	// tool uses this label for implementing provider's lifecycle operations.

controllers/clustertopology_controller_compute.go

@@ -18,11 +18,14 @@ package controllers
 
 import (
 	"context"
+	"fmt"
+	"strings"
 
 	"github.com/pkg/errors"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	kerrors "k8s.io/apimachinery/pkg/util/errors"
+	"k8s.io/apiserver/pkg/storage/names"
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1alpha4"
 	"sigs.k8s.io/cluster-api/controllers/external"
 	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
@@ -54,16 +57,16 @@ type machineDeploymentTopologyClass struct {
 // NOTE: please note that we are going to deal with two different type state, the current state as read from the API server,
 // and the desired state resulting from processing the clusterTopologyClass.
 type clusterTopologyState struct {
-	cluster               *clusterv1.Cluster               //nolint:structcheck
-	infrastructureCluster *unstructured.Unstructured       //nolint:structcheck
-	controlPlane          controlPlaneTopologyState        //nolint:structcheck
+	cluster               *clusterv1.Cluster
+	infrastructureCluster *unstructured.Unstructured
+	controlPlane          controlPlaneTopologyState
 	machineDeployments    []machineDeploymentTopologyState //nolint:structcheck
 }
 
 // controlPlaneTopologyState all the objects representing the state of a managed control plane.
 type controlPlaneTopologyState struct {
-	object                        *unstructured.Unstructured //nolint:structcheck
-	infrastructureMachineTemplate *unstructured.Unstructured //nolint:structcheck
+	object                        *unstructured.Unstructured
+	infrastructureMachineTemplate *unstructured.Unstructured
 }
 
 // machineDeploymentTopologyState all the objects representing the state of a managed deployment.
@@ -163,10 +166,242 @@ func (r *ClusterTopologyReconciler) getCurrentState(ctx context.Context, cluster
 	return nil, nil
 }
 
-// Computes the desired state of the Cluster topology.
-func (r *ClusterTopologyReconciler) computeDesiredState(ctx context.Context, input *clusterTopologyClass, current *clusterTopologyState) (*clusterTopologyState, error) {
-	// TODO: add compute logic
-	return nil, nil
+// computeDesiredState computes the desired state of the cluster topology.
+// NOTE: We are assuming all the required objects are provided as input; also, in case of any error,
+// the entire compute operation operation will fail. This might be improved in the future if support for reconciling
+// subset of a topology will be implemented.
+func (r *ClusterTopologyReconciler) computeDesiredState(_ context.Context, class *clusterTopologyClass, current *clusterTopologyState) (*clusterTopologyState, error) {
+	var err error
+	desiredState := &clusterTopologyState{}
+
+	// Compute the desired state of the InfrastructureCluster object.
+	if desiredState.infrastructureCluster, err = computeInfrastructureCluster(class, current); err != nil {
+		return nil, err
+	}
+
+	// If the ControlPlane object requires it, compute the InfrastructureMachineTemplate for the ControlPlane.
+	if class.clusterClass.Spec.ControlPlane.MachineInfrastructure != nil {
+		if desiredState.controlPlane.infrastructureMachineTemplate, err = computeControlPlaneInfrastructureMachineTemplate(class, current); err != nil {
+			return nil, err
+		}
+	}
+
+	// Compute the desired state of the ControlPlane object, eventually adding a reference to the
+	// InfrastructureMachineTemplate generated by the previous step.
+	if desiredState.controlPlane.object, err = computeControlPlane(class, current, desiredState.controlPlane.infrastructureMachineTemplate); err != nil {
+		return nil, err
+	}
+
+	// Compute the desired state for the Cluster object adding a reference to the
+	// InfrastructureCluster and the ControlPlane objects generated by the previous step.
+	desiredState.cluster = computeCluster(current, desiredState.infrastructureCluster, desiredState.controlPlane.object)
+
+	// TODO: implement generate desired state for machine deployments
+
+	return desiredState, nil
+}
+
+// computeInfrastructureCluster computes the desired state for the InfrastructureCluster object starting from the
+// corresponding template defined in ClusterClass.
+func computeInfrastructureCluster(class *clusterTopologyClass, current *clusterTopologyState) (*unstructured.Unstructured, error) {
+	infrastructureCluster, err := templateToObject(templateToInput{
+		template:              class.infrastructureClusterTemplate,
+		templateClonedFromRef: class.clusterClass.Spec.Infrastructure.Ref,
+		cluster:               current.cluster,
+		namePrefix:            fmt.Sprintf("%s-", current.cluster.Name),
+		currentObjectRef:      current.cluster.Spec.InfrastructureRef,
+	})
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to generate the InfrastructureCluster object from the %s", class.infrastructureClusterTemplate.GetKind())
+	}
+	return infrastructureCluster, nil
+}
+
+// computeControlPlaneInfrastructureMachineTemplate computes the desired state for InfrastructureMachineTemplate
+// that should be referenced by the ControlPlane object.
+func computeControlPlaneInfrastructureMachineTemplate(class *clusterTopologyClass, current *clusterTopologyState) (*unstructured.Unstructured, error) {
+	var currentInfrastructureMachineTemplate *corev1.ObjectReference
+	if current.controlPlane.object != nil {
+		var err error
+		if currentInfrastructureMachineTemplate, err = getNestedRef(current.controlPlane.object, "spec", "machineTemplate", "infrastructureRef"); err != nil {
+			return nil, errors.Wrap(err, "failed to get spec.machineTemplate.infrastructureRef for the current ControlPlane object")
+		}
+	}
+
+	controlPlaneInfrastructureMachineTemplate := templateToTemplate(templateToInput{
+		template:              class.controlPlane.infrastructureMachineTemplate,
+		templateClonedFromRef: objToRef(class.controlPlane.infrastructureMachineTemplate),
+		cluster:               current.cluster,
+		namePrefix:            fmt.Sprintf("%s-controlplane-", current.cluster.Name),
+		currentObjectRef:      currentInfrastructureMachineTemplate,
+		labels:                mergeMap(current.cluster.Spec.Topology.ControlPlane.Metadata.Labels, class.clusterClass.Spec.ControlPlane.Metadata.Labels),
+		annotations:           mergeMap(current.cluster.Spec.Topology.ControlPlane.Metadata.Annotations, class.clusterClass.Spec.ControlPlane.Metadata.Annotations),
+	})
+	return controlPlaneInfrastructureMachineTemplate, nil
+}
+
+// computeControlPlane computes the desired state for the ControlPlane object starting from the
+// corresponding template defined in ClusterClass.
+func computeControlPlane(class *clusterTopologyClass, current *clusterTopologyState, infrastructureMachineTemplate *unstructured.Unstructured) (*unstructured.Unstructured, error) {
+	controlPlane, err := templateToObject(templateToInput{
+		template:              class.controlPlane.template,
+		templateClonedFromRef: class.clusterClass.Spec.ControlPlane.Ref,
+		cluster:               current.cluster,
+		namePrefix:            fmt.Sprintf("%s-", current.cluster.Name),
+		currentObjectRef:      current.cluster.Spec.ControlPlaneRef,
+		labels:                mergeMap(current.cluster.Spec.Topology.ControlPlane.Metadata.Labels, class.clusterClass.Spec.ControlPlane.Metadata.Labels),
+		annotations:           mergeMap(current.cluster.Spec.Topology.ControlPlane.Metadata.Annotations, class.clusterClass.Spec.ControlPlane.Metadata.Annotations),
+	})
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to generate the ControlPlane object from the %s", class.controlPlane.template.GetKind())
+	}
+
+	// If the ControlPlane object requires it, add a reference to InfrastructureMachine template to be used for the control plane machines.
+	// NOTE: Once set for the first time, the reference name is not expected to changed in this step
+	// (instead it could change later during the reconciliation if template rotation is triggered)
+	if class.clusterClass.Spec.ControlPlane.MachineInfrastructure != nil {
+		if err := setNestedRef(controlPlane, infrastructureMachineTemplate, "spec", "machineTemplate", "infrastructureRef"); err != nil {
+			return nil, errors.Wrap(err, "failed to spec.machineTemplate.infrastructureRef in the ControlPlane object")
+		}
+	}
+
+	// If it is required to manage the number of replicas for the control plane, set the corresponding field.
+	// NOTE: If the Topology.controlPlane.replicas value is nil, it is assumed that the control plane controller
+	// does not implement support for this field and the ControlPlane object is generated without the number of Replicas.
+	if current.cluster.Spec.Topology.ControlPlane.Replicas != nil {
+		if err := unstructured.SetNestedField(controlPlane.UnstructuredContent(), int64(*current.cluster.Spec.Topology.ControlPlane.Replicas), "spec", "replicas"); err != nil {
+			return nil, errors.Wrap(err, "failed to set spec.replicas in the ControlPlane object")
+		}
+	}
+
+	// Sets the desired Kubernetes version for the control plane.
+	// TODO: improve this logic by adding support for version upgrade component by component
+	if err := unstructured.SetNestedField(controlPlane.UnstructuredContent(), current.cluster.Spec.Topology.Version, "spec", "version"); err != nil {
+		return nil, errors.Wrap(err, "failed to set spec.version in the ControlPlane object")
+	}
+
+	return controlPlane, nil
+}
+
+// computeCluster computes the desired state for the Cluster object.
+// NOTE: Some fields of the Cluster’s fields contribute to defining how a Cluster should look like (e.g. Cluster.Spec.Topology),
+// while some other fields should be managed as part of the actual Cluster (e.g. Cluster.Spec.ControlPlaneRef); in this func
+// we are concerned only about the latest group of fields.
+func computeCluster(current *clusterTopologyState, infrastructureCluster, controlPlane *unstructured.Unstructured) *clusterv1.Cluster {
+	cluster := &clusterv1.Cluster{}
+	current.cluster.DeepCopyInto(cluster)
+
+	// Enforce the topology labels.
+	// NOTE: The cluster label is added at creation time so this object could be read by the ClusterTopology
+	// controller immediately after creation, even before other controllers are going to add the label (if missing).
+	if cluster.Labels == nil {
+		cluster.Labels = map[string]string{}
+	}
+	cluster.Labels[clusterv1.ClusterLabelName] = cluster.Name
+	cluster.Labels[clusterv1.ClusterTopologyLabelName] = ""
+
+	// Set the references to the infrastructureCluster and controlPlane objects.
+	// NOTE: Once set for the first time, the references are not expected to change.
+	cluster.Spec.InfrastructureRef = objToRef(infrastructureCluster)
+	cluster.Spec.ControlPlaneRef = objToRef(controlPlane)
+
+	return cluster
+}
+
+type templateToInput struct {
+	template              *unstructured.Unstructured
+	templateClonedFromRef *corev1.ObjectReference
+	cluster               *clusterv1.Cluster
+	namePrefix            string
+	currentObjectRef      *corev1.ObjectReference
+	labels                map[string]string
+	annotations           map[string]string
+}
+
+// templateToObject generates an object from a template, taking care
+// of adding required labels (cluster, topology), annotations (clonedFrom)
+// and assigning a meaningful name (or reusing current reference name).
+func templateToObject(in templateToInput) (*unstructured.Unstructured, error) {
+	// Enforce the topology labels into the provided label set.
+	// NOTE: The cluster label is added at creation time so this object could be read by the ClusterTopology
+	// controller immediately after creation, even before other controllers are going to add the label (if missing).
+	labels := in.labels
+	if labels == nil {
+		labels = map[string]string{}
+	}
+	labels[clusterv1.ClusterLabelName] = in.cluster.Name
+	labels[clusterv1.ClusterTopologyLabelName] = ""
+
+	// Generate the object from the template.
+	// NOTE: OwnerRef can't be set at this stage; other controllers are going to add OwnerReferences when
+	// the object is actually created.
+	object, err := external.GenerateTemplate(&external.GenerateTemplateInput{
+		Template:    in.template,
+		TemplateRef: in.templateClonedFromRef,
+		Namespace:   in.cluster.Namespace,
+		Labels:      labels,
+		Annotations: in.annotations,
+		ClusterName: in.cluster.Name,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	// Ensure the generated objects have a meaningful name.
+	// NOTE: In case there is already a ref to this object in the Cluster, re-use the same name
+	// in order to simplify compare at later stages of the reconcile process.
+	object.SetName(names.SimpleNameGenerator.GenerateName(in.namePrefix))
+	if in.currentObjectRef != nil && len(in.currentObjectRef.Name) > 0 {
+		object.SetName(in.currentObjectRef.Name)
+	}
+
+	return object, nil
+}
+
+// templateToTemplate generates a template from an existing template, taking care
+// of adding required labels (cluster, topology), annotations (clonedFrom)
+// and assigning a meaningful name (or reusing current reference name).
+// NOTE: We are creating a copy of the ClusterClass template for each cluster so
+// it is possible to add cluster specific information without affecting the original object.
+func templateToTemplate(in templateToInput) *unstructured.Unstructured {
+	template := &unstructured.Unstructured{}
+	in.template.DeepCopyInto(template)
+
+	// Enforce the topology labels into the provided label set.
+	// NOTE: The cluster label is added at creation time so this object could be read by the ClusterTopology
+	// controller immediately after creation, even before other controllers are going to add the label (if missing).
+	labels := template.GetLabels()
+	if labels == nil {
+		labels = map[string]string{}
+	}
+	for key, value := range in.labels {
+		labels[key] = value
+	}
+	labels[clusterv1.ClusterLabelName] = in.cluster.Name
+	labels[clusterv1.ClusterTopologyLabelName] = ""
+	template.SetLabels(labels)
+
+	// Enforce cloned from annotations.
+	annotations := template.GetAnnotations()
+	if annotations == nil {
+		annotations = map[string]string{}
+	}
+	for key, value := range in.annotations {
+		annotations[key] = value
+	}
+	annotations[clusterv1.TemplateClonedFromNameAnnotation] = in.templateClonedFromRef.Name
+	annotations[clusterv1.TemplateClonedFromGroupKindAnnotation] = in.templateClonedFromRef.GroupVersionKind().GroupKind().String()
+	template.SetAnnotations(annotations)
+
+	// Ensure the generated template gets a meaningful name.
+	// NOTE: In case there is already an object ref to this template, it is required to re-use the same name
+	// in order to simplify compare at later stages of the reconcile process.
+	template.SetName(names.SimpleNameGenerator.GenerateName(in.namePrefix))
+	if in.currentObjectRef != nil && len(in.currentObjectRef.Name) > 0 {
+		template.SetName(in.currentObjectRef.Name)
+	}
+
+	return template
 }
 
 // getNestedRef returns the ref value of a nested field.
@@ -175,22 +410,22 @@ func getNestedRef(obj *unstructured.Unstructured, fields ...string) (*corev1.Obj
 	if v, ok, err := unstructured.NestedString(obj.UnstructuredContent(), append(fields, "apiVersion")...); ok && err == nil {
 		ref.APIVersion = v
 	} else {
-		return nil, errors.Errorf("failed to get reference apiVersion")
+		return nil, errors.Errorf("failed to get %s.apiVersion from %s", strings.Join(fields, "."), obj.GetKind())
 	}
 	if v, ok, err := unstructured.NestedString(obj.UnstructuredContent(), append(fields, "kind")...); ok && err == nil {
 		ref.Kind = v
 	} else {
-		return nil, errors.Errorf("failed to get reference Kind")
+		return nil, errors.Errorf("failed to get %s.kind from %s", strings.Join(fields, "."), obj.GetKind())
 	}
 	if v, ok, err := unstructured.NestedString(obj.UnstructuredContent(), append(fields, "name")...); ok && err == nil {
 		ref.Name = v
 	} else {
-		return nil, errors.Errorf("failed to get reference name")
+		return nil, errors.Errorf("failed to get %s.name from %s", strings.Join(fields, "."), obj.GetKind())
 	}
 	if v, ok, err := unstructured.NestedString(obj.UnstructuredContent(), append(fields, "namespace")...); ok && err == nil {
 		ref.Namespace = v
 	} else {
-		return nil, errors.Errorf("failed to get reference namespace")
+		return nil, errors.Errorf("failed to get %s.namespace from %s", strings.Join(fields, "."), obj.GetKind())
 	}
 	return ref, nil
 }
@@ -215,3 +450,16 @@ func objToRef(obj client.Object) *corev1.ObjectReference {
 		Name:       obj.GetName(),
 	}
 }
+
+// mergeMap merges two maps into another one.
+// NOTE: In case a key exists in both maps, the value in the first map is preserved.
+func mergeMap(a, b map[string]string) map[string]string {
+	m := make(map[string]string)
+	for k, v := range b {
+		m[k] = v
+	}
+	for k, v := range a {
+		m[k] = v
+	}
+	return m
+}