Add Topology CRD

Topology CRD is made by two different structs imported and abstracted
from PodSpec [1]:

1. TopologySpreadConstraint
2. Affinity

The above seems enough to draft a dedicated CR instead of exposing
those parameters through the service operators' API.
In addition, Affinity/AntiAffinity is imported from PodSpec [1] and
can override the default affinity policy defined in lib-common through
DistributePods function.

[1] https://pkg.go.dev/k8s.io/api/core/v1#PodSpec

Signed-off-by: Francesco Pantano <fpantano@redhat.com>

apis/topology/v1beta1/groupversion_info.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2025.
+
+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 v1beta1 contains API Schema definitions for the topology v1beta1 API group
+// +kubebuilder:object:generate=true
+// +groupName=topology.openstack.org
+package v1beta1
+
+import (
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/controller-runtime/pkg/scheme"
+)
+
+var (
+	// GroupVersion is group version used to register these objects
+	GroupVersion = schema.GroupVersion{Group: "topology.openstack.org", Version: "v1beta1"}
+
+	// SchemeBuilder is used to add go types to the GroupVersionKind scheme
+	SchemeBuilder = &scheme.Builder{GroupVersion: GroupVersion}
+
+	// AddToScheme adds the types in this group-version to the given scheme.
+	AddToScheme = SchemeBuilder.AddToScheme
+)

apis/topology/v1beta1/topology_types.go

@@ -0,0 +1,97 @@
+/*
+Copyright 2024.
+
+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 v1beta1
+
+import (
+	"context"
+	"github.com/openstack-k8s-operators/lib-common/modules/common/helper"
+	"github.com/openstack-k8s-operators/lib-common/modules/common/util"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+// TopologySpec defines the desired state of Topology
+type TopologySpec struct {
+	// +kubebuilder:validation:Optional
+	// APITopologySpreadConstraint exposes topologySpreadConstraint that are
+	// applied to the StatefulSet
+	TopologySpreadConstraint *[]corev1.TopologySpreadConstraint `json:"topologySpreadConstraint,omitempty"`
+
+	// Affinity exposes PodAffinity, PodAntiaffinity and NodeAffinity overrides
+	// that are applied to StatefulSet/Deployments
+	// +optional
+	Affinity *corev1.Affinity `json:"affinity,omitempty"`
+
+	//TODO: We could add NodeSelector here as it belongs to the same APIGroup
+}
+
+// TopologyStatus defines the observed state of Topology
+type TopologyStatus struct {
+
+	// ObservedGeneration - the most recent generation observed for this
+	// service.
+	ObservedGeneration int64 `json:"observedGeneration,omitempty"`
+}
+
+//+kubebuilder:object:root=true
+//+kubebuilder:subresource:status
+
+// Topology is the Schema for the topologies API
+type Topology struct {
+	metav1.TypeMeta   `json:",inline"`
+	metav1.ObjectMeta `json:"metadata,omitempty"`
+
+	Spec   TopologySpec   `json:"spec,omitempty"`
+	Status TopologyStatus `json:"status,omitempty"`
+}
+
+//+kubebuilder:object:root=true
+
+// TopologyList contains a list of Topology
+type TopologyList struct {
+	metav1.TypeMeta `json:",inline"`
+	metav1.ListMeta `json:"metadata,omitempty"`
+	Items           []Topology `json:"items"`
+}
+
+func init() {
+	SchemeBuilder.Register(&Topology{}, &TopologyList{})
+}
+
+// GetTopologyByName - a function exposed to the service operators
+// that need to retrieve the referenced topology by name
+func GetTopologyByName(
+	ctx context.Context,
+	h *helper.Helper,
+	name string,
+	namespace string,
+) (*Topology, string, error) {
+
+	topology := &Topology{}
+	var hash string = ""
+
+	err := h.GetClient().Get(ctx, types.NamespacedName{Name: name, Namespace: namespace}, topology)
+	if err != nil {
+		return topology, "", err
+	}
+	hash, err = util.ObjectHash(topology.Spec)
+	if err != nil {
+		return topology, "", err
+	}
+	return topology, hash, nil
+}