Support externalTrafficPolicy on the client Service

Adds BindCluster.spec.service.externalTrafficPolicy so DNS LoadBalancers
can preserve client source IPs (Local), which the source-IP ACLs on the
authoritative/resolver need to actually restrict external clients (Cluster
SNATs everything to node IPs).

- api: ClusterServiceSpec.externalTrafficPolicy (enum Cluster;Local)
- set it on the client Service for LoadBalancer/NodePort types
- regenerate CRDs + install.yaml

api/v1alpha1/bindcluster_types.go

@@ -33,6 +33,13 @@ type ClusterServiceSpec struct {
 	// +optional
 	LoadBalancerIP string `json:"loadBalancerIP,omitempty"`
 
+	// 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.
+	// +kubebuilder:validation:Enum=Cluster;Local
+	// +optional
+	ExternalTrafficPolicy corev1.ServiceExternalTrafficPolicy `json:"externalTrafficPolicy,omitempty"`
+
 	// Annotations added to the client-facing Service (e.g. PureLB/MetalLB hints).
 	// +optional
 	Annotations map[string]string `json:"annotations,omitempty"`

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

@@ -1094,6 +1094,15 @@ spec:
                     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.

config/crd/install.yaml

@@ -1399,6 +1399,15 @@ spec:
                     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.

internal/controller/bindcluster_controller.go

@@ -273,6 +273,10 @@ func (r *BindClusterReconciler) reconcileServices(ctx context.Context, c *bindv1
 			LoadBalancerIP: c.Spec.Service.LoadBalancerIP,
 		},
 	}
+	// externalTrafficPolicy is only valid for LoadBalancer/NodePort Services.
+	if svcType == corev1.ServiceTypeLoadBalancer || svcType == corev1.ServiceTypeNodePort {
+		client.Spec.ExternalTrafficPolicy = c.Spec.Service.ExternalTrafficPolicy
+	}
 	return r.upsertService(ctx, c, client)
 }
 

internal/controller/util.go

@@ -57,6 +57,7 @@ func (r *BindClusterReconciler) upsertService(ctx context.Context, c *bindv1alph
 	existing.Spec.Selector = desired.Spec.Selector
 	existing.Spec.Type = desired.Spec.Type
 	existing.Spec.LoadBalancerIP = desired.Spec.LoadBalancerIP
+	existing.Spec.ExternalTrafficPolicy = desired.Spec.ExternalTrafficPolicy
 	if desired.Annotations != nil {
 		if existing.Annotations == nil {
 			existing.Annotations = map[string]string{}