Merge pull request 'Add a primary (write) Service routing to pod-0' (#7) from benvin/primary-write-service into main

Reviewed-on: #7

api/v1alpha1/bindcluster_types.go

@@ -105,10 +105,18 @@ type BindClusterSpec struct {
 	// +optional
 	Resources corev1.ResourceRequirements `json:"resources,omitempty"`
 
-	// Service controls how the cluster is exposed.
+	// Service controls how the cluster is exposed for reads (all pods).
 	// +optional
 	Service ClusterServiceSpec `json:"service,omitempty"`
 
+	// PrimaryService, when set, creates an additional Service routing only to the
+	// primary pod (ordinal 0) — the write endpoint for RFC2136/nsupdate, since
+	// secondaries reject updates. Reads still use Service (all pods). Use
+	// ClusterIP for in-cluster writers (e.g. external-dns) or LoadBalancer for
+	// external writers.
+	// +optional
+	PrimaryService *ClusterServiceSpec `json:"primaryService,omitempty"`
+
 	// NodeSelector for the BIND pods.
 	// +optional
 	NodeSelector map[string]string `json:"nodeSelector,omitempty"`

api/v1alpha1/zz_generated.deepcopy.go

@@ -301,6 +301,11 @@ func (in *BindClusterSpec) DeepCopyInto(out *BindClusterSpec) {
 	}
 	in.Resources.DeepCopyInto(&out.Resources)
 	in.Service.DeepCopyInto(&out.Service)
+	if in.PrimaryService != nil {
+		in, out := &in.PrimaryService, &out.PrimaryService
+		*out = new(ClusterServiceSpec)
+		(*in).DeepCopyInto(*out)
+	}
 	if in.NodeSelector != nil {
 		in, out := &in.NodeSelector, &out.NodeSelector
 		*out = make(map[string]string, len(*in))

config/crd/bases/bind.unkin.net_bindclusters.yaml

@@ -1013,6 +1013,41 @@ spec:
                   type: string
                 description: NodeSelector for the BIND pods.
                 type: object
+              primaryService:
+                description: |-
+                  PrimaryService, when set, creates an additional Service routing only to the
+                  primary pod (ordinal 0) — the write endpoint for RFC2136/nsupdate, since
+                  secondaries reject updates. Reads still use Service (all pods). Use
+                  ClusterIP for in-cluster writers (e.g. external-dns) or LoadBalancer for
+                  external writers.
+                properties:
+                  annotations:
+                    additionalProperties:
+                      type: string
+                    description: Annotations added to the client-facing Service (e.g.
+                      PureLB/MetalLB hints).
+                    type: object
+                  externalTrafficPolicy:
+                    description: |-
+                      ExternalTrafficPolicy for a LoadBalancer/NodePort Service. Local preserves
+                      client source IPs (required for source-IP ACLs on the DNS servers) but
+                      only routes to nodes running a pod. Defaults to Cluster.
+                    enum:
+                    - Cluster
+                    - Local
+                    type: string
+                  loadBalancerIP:
+                    description: LoadBalancerIP requests a specific address when Type
+                      is LoadBalancer.
+                    type: string
+                  type:
+                    description: Type of the client-facing Service. Defaults to ClusterIP.
+                    enum:
+                    - ClusterIP
+                    - LoadBalancer
+                    - NodePort
+                    type: string
+                type: object
               recursion:
                 description: |-
                   Recursion overrides the default per-mode recursion setting. When nil,
@@ -1086,7 +1121,8 @@ spec:
                     type: object
                 type: object
               service:
-                description: Service controls how the cluster is exposed.
+                description: Service controls how the cluster is exposed for reads
+                  (all pods).
                 properties:
                   annotations:
                     additionalProperties:

config/crd/install.yaml

@@ -1318,6 +1318,41 @@ spec:
                   type: string
                 description: NodeSelector for the BIND pods.
                 type: object
+              primaryService:
+                description: |-
+                  PrimaryService, when set, creates an additional Service routing only to the
+                  primary pod (ordinal 0) — the write endpoint for RFC2136/nsupdate, since
+                  secondaries reject updates. Reads still use Service (all pods). Use
+                  ClusterIP for in-cluster writers (e.g. external-dns) or LoadBalancer for
+                  external writers.
+                properties:
+                  annotations:
+                    additionalProperties:
+                      type: string
+                    description: Annotations added to the client-facing Service (e.g.
+                      PureLB/MetalLB hints).
+                    type: object
+                  externalTrafficPolicy:
+                    description: |-
+                      ExternalTrafficPolicy for a LoadBalancer/NodePort Service. Local preserves
+                      client source IPs (required for source-IP ACLs on the DNS servers) but
+                      only routes to nodes running a pod. Defaults to Cluster.
+                    enum:
+                    - Cluster
+                    - Local
+                    type: string
+                  loadBalancerIP:
+                    description: LoadBalancerIP requests a specific address when Type
+                      is LoadBalancer.
+                    type: string
+                  type:
+                    description: Type of the client-facing Service. Defaults to ClusterIP.
+                    enum:
+                    - ClusterIP
+                    - LoadBalancer
+                    - NodePort
+                    type: string
+                type: object
               recursion:
                 description: |-
                   Recursion overrides the default per-mode recursion setting. When nil,
@@ -1391,7 +1426,8 @@ spec:
                     type: object
                 type: object
               service:
-                description: Service controls how the cluster is exposed.
+                description: Service controls how the cluster is exposed for reads
+                  (all pods).
                 properties:
                   annotations:
                     additionalProperties:

internal/controller/bindcluster_controller.go

@@ -277,7 +277,52 @@ func (r *BindClusterReconciler) reconcileServices(ctx context.Context, c *bindv1
 	if svcType == corev1.ServiceTypeLoadBalancer || svcType == corev1.ServiceTypeNodePort {
 		client.Spec.ExternalTrafficPolicy = c.Spec.Service.ExternalTrafficPolicy
 	}
-	return r.upsertService(ctx, c, client)
+	if err := r.upsertService(ctx, c, client); err != nil {
+		return err
+	}
+
+	// Primary (write) Service: routes only to pod-0. Created when configured,
+	// deleted when removed.
+	return r.reconcilePrimaryService(ctx, c, dnsPorts)
+}
+
+func (r *BindClusterReconciler) reconcilePrimaryService(ctx context.Context, c *bindv1alpha1.BindCluster, dnsPorts []corev1.ServicePort) error {
+	name := primaryServiceName(c.Name)
+	if c.Spec.PrimaryService == nil {
+		var existing corev1.Service
+		err := r.Get(ctx, types.NamespacedName{Namespace: c.Namespace, Name: name}, &existing)
+		if apierrors.IsNotFound(err) {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		return client.IgnoreNotFound(r.Delete(ctx, &existing))
+	}
+
+	ps := c.Spec.PrimaryService
+	psType := ps.Type
+	if psType == "" {
+		psType = corev1.ServiceTypeClusterIP
+	}
+	svc := &corev1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:        name,
+			Namespace:   c.Namespace,
+			Labels:      commonLabels(c.Name),
+			Annotations: ps.Annotations,
+		},
+		Spec: corev1.ServiceSpec{
+			Type:           psType,
+			Selector:       primaryPodSelector(c.Name),
+			Ports:          dnsPorts,
+			LoadBalancerIP: ps.LoadBalancerIP,
+		},
+	}
+	if psType == corev1.ServiceTypeLoadBalancer || psType == corev1.ServiceTypeNodePort {
+		svc.Spec.ExternalTrafficPolicy = ps.ExternalTrafficPolicy
+	}
+	return r.upsertService(ctx, c, svc)
 }
 
 func (r *BindClusterReconciler) reconcileStatefulSet(ctx context.Context, c *bindv1alpha1.BindCluster) (*appsv1.StatefulSet, error) {

internal/controller/helpers.go

@@ -29,11 +29,20 @@ const (
 )
 
 func headlessServiceName(cluster string) string { return cluster + "-headless" }
-func clientServiceName(cluster string) string   { return cluster }
+func primaryServiceName(cluster string) string  { return cluster + "-primary" }
-func primaryPodName(cluster string) string      { return cluster + "-0" }
+
-func configMapName(cluster string) string       { return cluster + "-config" }
+// primaryPodSelector selects only the primary pod (ordinal 0) via the stable
-func keysSecretName(cluster string) string      { return cluster + "-keys" }
+// StatefulSet pod-name label, for the write Service.
-func rndcSecretName(cluster string) string      { return cluster + "-rndc" }
+func primaryPodSelector(cluster string) map[string]string {
+	s := commonLabels(cluster)
+	s["statefulset.kubernetes.io/pod-name"] = primaryPodName(cluster)
+	return s
+}
+func clientServiceName(cluster string) string { return cluster }
+func primaryPodName(cluster string) string    { return cluster + "-0" }
+func configMapName(cluster string) string     { return cluster + "-config" }
+func keysSecretName(cluster string) string    { return cluster + "-keys" }
+func rndcSecretName(cluster string) string    { return cluster + "-rndc" }
 
 // primaryAddress is the in-cluster DNS name of the primary pod (ordinal 0).
 func primaryAddress(cluster, namespace string) string {