ELBv2 controller panic

[jwilms1971]

I am trying to modify an existing network load balancer (created via CloudFormation) by changing the allocated subnets. Here is the YAML I submitted to the ELBv2 controller:

apiVersion: elbv2.services.k8s.aws/v1alpha1
kind: LoadBalancer
metadata:
  name: eks-v2-blueprints-cluster-nlb
  annotations:
    services.k8s.aws/adoption-policy: adopt-or-create
    services.k8s.aws/adoption-fields: |
      {
        "name": "k8s-argocd-blueprin-61bea9c603"
      }
spec:
  name: k8s-argocd-blueprin-61bea9c603
  subnets:
  - subnet-06f51576daf32f89b
  - subnet-0f92d1276ed15bf64
  - subnet-065970a909617b02a 

The controller goes into a panic:

{"level":"error","ts":"2025-07-03T06:03:01.295Z","msg":"Reconciler error","controller":"loadbalancer","controllerGroup":"elbv2.services.k8s.aws","controllerKind":"LoadBalancer","LoadBalancer":{"name":"eks-v2-blueprints-cluster-nlb","namespace":"ack-system"},"namespace":"ack-system","name":"eks-v2-blueprints-cluster-nlb","reconcileID":"6fa856d9-e31b-4c74-b45e-3c6856972a0a","error":"panic: runtime error: invalid memory address or nil pointer dereference [recovered]","stacktrace":"sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler\n\t/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.20.4/pkg/internal/controller/controller.go:347\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).processNextWorkItem\n\t/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.20.4/pkg/internal/controller/controller.go:294\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func2.2\n\t/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.20.4/pkg/internal/controller/controller.go:255"}

To ensure I wasn't making any configuration mistakes I also submitted the resource in using adopt without create which yielded the following result:

$ k describe loadbalancers
Name:         eks-v2-blueprints-cluster-nlb
Namespace:    ack-system
Labels:       <none>
Annotations:  services.k8s.aws/adopted: true
              services.k8s.aws/adoption-fields:
                {
                  "name": "k8s-argocd-blueprin-61bea9c603"
                }
              services.k8s.aws/adoption-policy: adopt
API Version:  elbv2.services.k8s.aws/v1alpha1
Kind:         LoadBalancer
Metadata:
  Creation Timestamp:  2025-07-03T06:11:03Z
  Finalizers:
    finalizers.elbv2.services.k8s.aws/LoadBalancer
  Generation:        2
  Resource Version:  105113
  UID:               c8384973-f4f7-43fe-9311-e1576be9727d
Spec:
  Attributes:
    Key:            dns_record.client_routing_policy
    Value:          any_availability_zone
    Key:            access_logs.s3.prefix
    Value:
    Key:            deletion_protection.enabled
    Value:          false
    Key:            zonal_shift.config.enabled
    Value:          false
    Key:            load_balancing.cross_zone.enabled
    Value:          false
    Key:            access_logs.s3.enabled
    Value:          false
    Key:            access_logs.s3.bucket
    Value:
  Ip Address Type:  ipv4
  Name:             k8s-argocd-blueprin-61bea9c603
  Scheme:           internet-facing
  Security Groups:
    sg-0618a68283f1b8e18
    sg-0cb86f30aa77383d2
  Subnets:
    subnet-06f51576daf32f89b
    subnet-0f92d1276ed15bf64
    subnet-065970a909617b02a
  Tags:
    Key:    service.k8s.aws/resource
    Value:  LoadBalancer
    Key:    service.k8s.aws/stack
    Value:  argocd/blueprints-addon-argocd-server
    Key:    elbv2.k8s.aws/cluster
    Value:  hsbc-prod-eks-v2-blueprints-cluster
  Type:     network
Status:
  Ack Resource Metadata:
    Arn:               arn:aws:elasticloadbalancing:eu-west-2:000000000000:loadbalancer/net/k8s-argocd-blueprin-61bea9c603/5b5ece2886e7a2da  
    Owner Account ID:  000000000000
    Region:            eu-west-2
  Availability Zones:
    Subnet ID:               subnet-033ba98d248b2fcbd
    Zone Name:               eu-west-2b
    Subnet ID:               subnet-0b477b8fee674a8ac
    Zone Name:               eu-west-2c
    Subnet ID:               subnet-0e1a51c61ebb9d110
    Zone Name:               eu-west-2a
  Canonical Hosted Zone ID:  ZD4D7Y8KGAS4G
  Conditions:
    Last Transition Time:  2025-07-03T06:11:03Z
    Message:               Resource synced successfully
    Reason:
    Status:                True
    Type:                  ACK.ResourceSynced
  Created Time:            2025-07-02T23:03:35Z
  Dns Name:                k8s-argocd-blueprin-61bea9c603-5b5ece2886e7a2da.elb.eu-west-2.amazonaws.com
  State:
    Code:  active
  Vpc ID:  vpc-0cc98e76c53211f70
Events:    <none>

[github-actions]

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[knottnt]

@jwilms1971: Created a PR to fix the panic issue, but it looks like there's some additional work to be done in order to support your use case. After resolving the panic I can see that the ELBv2 controller doesn't properly update the Status fields when using adopt-or-create. Additionally, some feature work will be required to add support for updating the Subnets as the update operation only support Attributes and Tags currently.

I'll try to resolve those additional issues in future PRs.