feat: preemptive scheduling

api/clusters/v1alpha1/cluster_types.go

@@ -4,9 +4,9 @@ import (
 	"encoding/json"
 	"strings"
 
+	"github.com/openmcp-project/controller-utils/pkg/collections"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
-	"k8s.io/apimachinery/pkg/util/sets"
 )
 
 // ClusterSpec defines the desired state of Cluster
@@ -122,18 +122,40 @@ func (cs *ClusterStatus) SetProviderStatus(from any) error {
 
 // GetTenancyCount returns the number of ClusterRequests currently pointing to this cluster.
 // This is determined by counting the finalizers that have the corresponding prefix.
-// Note that only unique finalizers are counted, so if there are multiple identical request finalizers
-// (which should not happen), this method's return value might not match the actual number of finalizers with the prefix.
 func (c *Cluster) GetTenancyCount() int {
-	return c.GetRequestUIDs().Len()
+	return collections.AggregateMap(c.GetRequestUIDs(), func(_ string, count int, current int) int {
+		return count + current
+	}, 0)
 }
 
-// GetRequestUIDs returns the UIDs of all ClusterRequests that have marked this cluster with a corresponding finalizer.
-func (c *Cluster) GetRequestUIDs() sets.Set[string] {
-	res := sets.New[string]()
+// GetRequestUIDs returns the UIDs of all ClusterRequests that have marked this cluster with a corresponding finalizer,
+// mapped to their respective counts.
+// Note that a regular request is currently expected to have exactly one finalizer, so the counts for each UID should be 1.
+func (c *Cluster) GetRequestUIDs() map[string]int {
+	res := map[string]int{}
 	for _, fin := range c.Finalizers {
 		if strings.HasPrefix(fin, RequestFinalizerOnClusterPrefix) {
-			res.Insert(strings.TrimPrefix(fin, RequestFinalizerOnClusterPrefix))
+			res[strings.TrimPrefix(fin, RequestFinalizerOnClusterPrefix)]++
+		}
+	}
+	return res
+}
+
+// GetPreemptiveTenancyCount returns the number of PreemptiveClusterRequests currently pointing to this cluster.
+// This is determined by counting the finalizers that have the corresponding prefix.
+func (c *Cluster) GetPreemptiveTenancyCount() int {
+	return collections.AggregateMap(c.GetPreemptiveRequestUIDs(), func(_ string, count int, current int) int {
+		return count + current
+	}, 0)
+}
+
+// GetPreemptiveRequestUIDs returns the UIDs of all PreemptiveClusterRequests that have marked this cluster with a corresponding finalizer,
+// mapped to their respective counts.
+func (c *Cluster) GetPreemptiveRequestUIDs() map[string]int {
+	res := map[string]int{}
+	for _, fin := range c.Finalizers {
+		if strings.HasPrefix(fin, PreemptiveRequestFinalizerOnClusterPrefix) {
+			res[strings.TrimPrefix(fin, PreemptiveRequestFinalizerOnClusterPrefix)]++
 		}
 	}
 	return res

api/clusters/v1alpha1/clusterrequest_types.go

@@ -67,7 +67,7 @@ type ClusterRequest struct {
 type ClusterRequestList struct {
 	metav1.TypeMeta `json:",inline"`
 	metav1.ListMeta `json:"metadata,omitempty"`
-	Items           []Cluster `json:"items"`
+	Items           []ClusterRequest `json:"items"`
 }
 
 func init() {

api/clusters/v1alpha1/constants.go

@@ -70,16 +70,20 @@ const (
 	// For AccessRequests, the generic controller that is part of the openMCP Operator sets it.
 	ProviderLabel = GroupName + "/provider"
 
-	// DeleteWithoutRequestsLabel marks that the corresponding cluster can be deleted if the scheduler removes the last request pointing to it.
-	// Its value must be "true" for the label to take effect.
-	DeleteWithoutRequestsLabel = GroupName + "/delete-without-requests"
 	// ProfileLabel is used to make the profile information easily accessible on AccessRequests.
 	ProfileLabel = GroupName + "/profile"
 )
 
 const (
+	// DeleteWithoutRequestsLabel marks that the corresponding cluster can be deleted if the scheduler removes the last request pointing to it.
+	// Its value must be "true" for the label to take effect.
+	DeleteWithoutRequestsLabel = GroupName + "/delete-without-requests"
 	// ClusterRequestFinalizer is the finalizer used on ClusterRequest resources
 	ClusterRequestFinalizer = GroupName + "/request"
 	// RequestFinalizerOnClusterPrefix is the prefix for the finalizers that mark a Cluster as being referenced by a ClusterRequest.
 	RequestFinalizerOnClusterPrefix = "request." + GroupName + "/"
+	// PreemptiveRequestFinalizerOnClusterPrefix is the prefix for the finalizers that mark a Cluster as being referenced by a preemptive ClusterRequest.
+	PreemptiveRequestFinalizerOnClusterPrefix = "preemptive." + GroupName + "/"
+	// SchedulerCreationIDLabel can be used to track which scheduling operation created a specific Cluster. Mainly for internal purposes.
+	SchedulerCreationIDLabel = GroupName + "/creation-id"
 )

api/clusters/v1alpha1/constants/reasons.go

@@ -11,4 +11,6 @@ const (
 	ReasonConfigurationProblem = "ConfigurationProblem"
 	// ReasonInternalError indicates that something went wrong internally.
 	ReasonInternalError = "InternalError"
+	// ReasonSchedulingFailed indicates that there was a problem with scheduling a request.
+	ReasonSchedulingFailed = "SchedulingFailed"
 )

api/clusters/v1alpha1/preemptiveclusterrequest_types.go

@@ -0,0 +1,63 @@
+package v1alpha1
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+type PreemptiveClusterRequestSpec struct {
+	// Purpose is the purpose of the requested cluster.
+	// +kubebuilder:validation:XValidation:rule="self == oldSelf",message="purpose is immutable"
+	// +kubebuilder:validation:MinLength=1
+	Purpose string `json:"purpose"`
+
+	// Workload specifies for how many workloads this preemptive cluster request should account.
+	// Must be greater than 0.
+	// +kubebuilder:validation:Minimum=1
+	Workload int `json:"workload"`
+}
+
+type PreemptiveClusterRequestStatus struct {
+	CommonStatus `json:",inline"`
+
+	// Phase is the current phase of the request.
+	// +kubebuilder:default=Pending
+	// +kubebuilder:validation:Enum=Pending;Granted;Denied
+	Phase RequestPhase `json:"phase"`
+}
+
+// +kubebuilder:object:root=true
+// +kubebuilder:subresource:status
+// +kubebuilder:resource:shortName=pcr;pcreq
+// +kubebuilder:metadata:labels="openmcp.cloud/cluster=platform"
+// +kubebuilder:selectablefield:JSONPath=".spec.purpose"
+// +kubebuilder:selectablefield:JSONPath=".status.phase"
+// +kubebuilder:printcolumn:JSONPath=".spec.purpose",name="Purpose",type=string
+// +kubebuilder:printcolumn:JSONPath=".spec.workload",name="Workload",type=string
+// +kubebuilder:printcolumn:JSONPath=".status.phase",name="Phase",type=string
+
+type PreemptiveClusterRequest struct {
+	metav1.TypeMeta   `json:",inline"`
+	metav1.ObjectMeta `json:"metadata,omitempty"`
+
+	Spec   PreemptiveClusterRequestSpec   `json:"spec,omitempty"`
+	Status PreemptiveClusterRequestStatus `json:"status,omitempty"`
+}
+
+// +kubebuilder:object:root=true
+
+// PreemptiveClusterRequestList contains a list of Cluster
+type PreemptiveClusterRequestList struct {
+	metav1.TypeMeta `json:",inline"`
+	metav1.ListMeta `json:"metadata,omitempty"`
+	Items           []PreemptiveClusterRequest `json:"items"`
+}
+
+func init() {
+	SchemeBuilder.Register(&PreemptiveClusterRequest{}, &PreemptiveClusterRequestList{})
+}
+
+// FinalizerForCluster returns the finalizer that is used to mark that a specific request has pointed to a specific cluster.
+// Apart from preventing the Cluster's deletion, this information is used to recover the Cluster if the status of the PreemptiveClusterRequest ever gets lost.
+func (cr *PreemptiveClusterRequest) FinalizerForCluster() string {
+	return PreemptiveRequestFinalizerOnClusterPrefix + string(cr.UID)
+}