OCPBUGS-84508: Fix NLB name parsing for EKS Auto Mode hostnames

control-plane-operator/controllers/awsprivatelink/awsprivatelink_controller.go

@@ -170,7 +170,7 @@ func (r *PrivateServiceObserver) Reconcile(ctx context.Context, req ctrl.Request
 			Namespace: r.HCPNamespace,
 		},
 	}
-	lbName := strings.Split(strings.Split(svc.Status.LoadBalancer.Ingress[0].Hostname, ".")[0], "-")[0]
+	lbName := extractNLBName(svc.Status.LoadBalancer.Ingress[0].Hostname)
 	if _, err := r.CreateOrUpdate(ctx, r, awsEndpointService, func() error {
 		awsEndpointService.Spec.NetworkLoadBalancerName = lbName
 		if hcp.Spec.Platform.AWS != nil {
@@ -184,6 +184,31 @@ func (r *PrivateServiceObserver) Reconcile(ctx context.Context, req ctrl.Request
 	return ctrl.Result{}, nil
 }
 
+// extractNLBName extracts the NLB name from its DNS hostname.
+//
+// AWS NLB DNS format is "{name}-{id}.elb.{region}.amazonaws.com"
+// where {name} is the value passed to CreateLoadBalancer and {id} is an
+// AWS-assigned hex suffix.
+// Ref: https://docs.aws.amazon.com/elasticloadbalancing/latest/network/network-load-balancers.html#dns-name
+//
+// The in-tree cloud provider generates hyphen-free names ("a" + UID),
+// but the AWS LB Controller (EKS Auto Mode) uses "k8s-{ns}-{svc}-{hash}".
+// We strip only the last dash-delimited segment (the AWS-assigned ID)
+// because {id} is always hex (no hyphens), as shown in every AWS API
+// example and required structurally — since {name} may contain hyphens,
+// a hyphenated {id} would make the format ambiguous.
+//
+// In-tree name generation: https://github.com/kubernetes/cloud-provider/blob/v0.32.3/cloud.go#L89-L98
+// AWS LB Controller name generation: https://github.com/kubernetes-sigs/aws-load-balancer-controller/blob/v2.12.0/pkg/service/model_build_load_balancer.go#L591-L608
+func extractNLBName(hostname string) string {
+	firstLabel := strings.Split(hostname, ".")[0]
+	lastDash := strings.LastIndex(firstLabel, "-")
+	if lastDash == -1 {
+		return firstLabel
+	}
+	return firstLabel[:lastDash]
+}
+
 // errDependencyViolation is returned when AWS reports a DependencyViolation,
 // indicating the VPC endpoint is still being deleted. The caller translates
 // this into a controlled requeue rather than an error-driven requeue.

control-plane-operator/controllers/awsprivatelink/awsprivatelink_controller_test.go

@@ -910,3 +910,33 @@ func TestReconcileDeletionSharedVPC(t *testing.T) {
 		})
 	}
 }
+
+func TestExtractNLBName(t *testing.T) {
+	testCases := []struct {
+		name     string
+		hostname string
+		expected string
+	}{
+		{
+			name:     "When standard NLB hostname it should extract name without hyphens",
+			hostname: "a1b2c3d4e5f6g7-1234567890abcdef.elb.us-east-1.amazonaws.com",
+			expected: "a1b2c3d4e5f6g7",
+		},
+		{
+			name:     "When EKS Auto Mode NLB hostname it should extract full name with hyphens",
+			hostname: "k8s-clusters-kubeapis-db6fee3a62-8008741421d14306.elb.us-east-1.amazonaws.com",
+			expected: "k8s-clusters-kubeapis-db6fee3a62",
+		},
+		{
+			name:     "When hostname has no hyphens it should return the first label as-is",
+			hostname: "somename.elb.us-east-1.amazonaws.com",
+			expected: "somename",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			g := NewWithT(t)
+			g.Expect(extractNLBName(tc.hostname)).To(Equal(tc.expected))
+		})
+	}
+}