Configured Load Balancer fronting the kubernetes API Server Failed to realize kubernetes api-server LoadBalancer service. Reason: "FailedRealizeNSXResource". Please check the NSX Edge cluster associated with the kubernetes cluster.

Products

• VMware NSX
• VMware Cloud Foundation
• VMware vSphere Kubernetes Service

Issue/Introduction

• VCF 9.0 is in use.
• Attempting to configure a Supervisor Cluster within vCenter fails with the following:
  
  Configured Load Balancer fronting the kubernetes API Server Failed to realize kubernetes api-server LoadBalancer service. Reason: "FailedRealizeNSXResource". Please check the NSX Edge cluster associated with the kubernetes cluster.


• From within the NSX User Interface, the Load Balancer is realized.
• Within the vCenter the WCP logs shows the following:
  
  /var/log/vmware/wcp/wcpsvc.log
[Timestamp] debug wcp [apiserver/manager.go:247] [opID=[UUID]] Added event for kube-apiserver-lb-svc service: &Event{ObjectMeta:{kube-apiserver-lb-svc.  kube-system  [UUID] 0 [Timestamp] <nil> <nil> map[] map[] [] [] [{nsx-ncp Update v1 [Timestamp] FieldsV1 {"f:count":{},"f:firstTimestamp":{},"f:involvedObject":{},"f:lastTim
estamp":{},"f:message":{},"f:reason":{},"f:source":{"f:component":{},"f:host":{}},"f:type":{}} }]},InvolvedObject:ObjectReference{Kind:Service,Namespace:kube-system,Name:kube-apiserver-lb-svc,[UUID],APIVers
ion:,ResourceVersion:[UUID],FieldPath:,},Reason:FailedRealizeNSXResource,Message:Generic error occurred during realizing network for Service,Source:EventSource{Component:nsx-container-ncp,Host:[UUID],},FirstTimest
amp:[Timestamp],LastTimestamp:2025-07-30 14:09:44 +0000 UTC,Count:1301,Type:Warning,EventTime:0001-01-01 00:00:00 +0000 UTC,Series:nil,Action:,Related:nil,ReportingController:,ReportingInstance:,}
  
  
• On the K8s Master node the NCP logs shows the following:
  
  ncp.log
[Timestamp] stderr F [ncp GreenThread-38 W] nsx_ujo.ncp.k8s.service_lb_controller Encountered retryable error while processing L4 Lb service [UUID]: Lbs kube-system is not found
[Timestamp] stderr F [ncp GreenThread-38 I] nsx_ujo.common.controller ServiceLbController worker 3 failed to sync [UUID] due to retryable exception: Lbs kube-system is not found
[Timestamp] stderr F [ncp GreenThread-37 W] nsx_ujo.ncp.k8s.service_lb_controller Encountered retryable error while processing L4 Lb service [UUID]: Lbs kube-system is not found
[Timestamp] stderr F [ncp GreenThread-37 I] nsx_ujo.common.controller ServiceLbController worker 2 failed to sync [UUID] due to retryable exception: Lbs kube-system is not found
  
  
• On the K8s Master node the kube-apiserver-lb-svc is in a pending state.
  
  kubectl get svc -A -o wide
...
kube-system   kube-apiserver-lb-svc   LoadBalancer   [IP]    <pending>     [Port]:[Port]/TCP,[Port]:[Port]/TCP    [X]d   component=kube-apiserver
..
  
  
• Describe on the service shows the FailedRealizeNSXResource event.
  
  root@node# kubectl describe services kube-apiserver-lb-svc -n kube-system
Name:                     kube-apiserver-lb-svc
Namespace:                kube-system
Labels:                   service.route.lbapi.run.tanzu.vmware.com/gateway-name=kube-apiserver-lb-svc
                          service.route.lbapi.run.tanzu.vmware.com/gateway-namespace=kube-system
                          service.route.lbapi.run.tanzu.vmware.com/type=direct
Annotations:              <none>
Selector:                 component=kube-apiserver
Type:                     LoadBalancer
IP Family Policy:         SingleStack
IP Families:              IPv4
IP:                       [UUID]
IPs:                      [UUID]
Port:                     nginx  [Port]/TCP
TargetPort:               [Port]/TCP
NodePort:                 nginx  [Port]/TCP
Endpoints:                [IP]:[Port]
Port:                     kube-apiserver  [Port]/TCP
TargetPort:               [Port]/TCP
NodePort:                 kube-apiserver  [Port]/TCP
Endpoints:                [IP]:[Port]
Session Affinity:         None
External Traffic Policy:  Cluster
Events:
  Type     Reason                    Age                   From               Message
  ----     ------                    ----                  ----               -------
  Warning  FailedRealizeNSXResource  18m (x1296 over 18d)  nsx-container-ncp  Generic error occurred during realizing network for Service
  
  
• Within the VPC Connectivity Profile the N-S Services and/or the Default Output NAT is disabled.

Environment

VMware vSphere Kubernetes Service 9.0
VMware Cloud Foundation 9.0
VMware NSX 9.0

Resolution

This error is caused by a configuration issue.

To resolve:

1. Enable N-S Services and the Default Output NAT in the VPC Connectivity Profile
2. Restart the WCP service on the vCenter 
   
   service-control --restart wcp