After ingress crosses ns proxy svc, the listening list of ALB is empty.

[ColeSu-n]

I created ingress and an ExternalName svc in the A namespace. This svc pointed to an svc under the B namespace. Then I saw that the listening target of alb was empty.
This will result in accessing the domain name in ingress get 503 Service Temporarily Unavailable

kind: Ingress
apiVersion: networking.k8s.io/v1
metadata:
  name: test
  namespace: cms
spec:
  ingressClassName: alb
  rules:
    - host: testalb.mmm.yyy
      http:
        paths:
          - path: /
            pathType: ImplementationSpecific
            backend:
              service:
                name: svc1
                port:
                  number: 80
    - host: testargocd.mmm.yyy
      http:
        paths:
          - path: /
            pathType: ImplementationSpecific
            backend:
              service:
                name: argocd
                port:
                  number: 80

kind: Service
apiVersion: v1
metadata:
  name: argocd
  namespace: cms
spec:
  ports:
    - name: http
      protocol: TCP
      port: 80
      targetPort: 80
  type: ExternalName
  sessionAffinity: None
  externalName: argocd-demo.tools.svc.cluster.local

kind: Service
apiVersion: v1
metadata:
  name: argocd-demo
  namespace: tools
  labels:
    app: argocd-demo
spec:
  ports:
    - name: http
      protocol: TCP
      port: 80
      targetPort: 8080
  selector:
    app: argocd-demo
  ipFamilyPolicy: SingleStack
  internalTrafficPolicy: Cluster

kind: Deployment
apiVersion: apps/v1
metadata:
  name: argocd-demo
  namespace: tools
  labels:
    app: argocd-demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: argocd-demo
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: argocd-demo
    spec:
      containers:
        - name: container-9nac5k
          image: 'argoproj/rollouts-demo:blue'
          resources: {}
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
          imagePullPolicy: IfNotPresent
      restartPolicy: Always
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 25%
      maxSurge: 25%
  revisionHistoryLimit: 10
  progressDeadlineSeconds: 600

Target group in ALB listening rule

k describe ing -n cms

Events:
  Type     Reason                  Age                   From     Message
  ----     ------                  ----                  ----     -------
  Warning  FailedDeployModel       52m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: CreateTargetGroup, https response error StatusCode: 400, RequestID: 5b242618-6175-4464-80b8-c130c814e1f3, api error ValidationError: 1 validation error detected: Value '0' at 'port' failed to satisfy constraint: Member must have value greater than or equal to 1
  Warning  FailedDeployModel       48m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: CreateTargetGroup, https response error StatusCode: 400, RequestID: 6b5a3fb2-37b4-40cf-b9d2-4730fbce8780, api error ValidationError: 1 validation error detected: Value '0' at 'port' failed to satisfy constraint: Member must have value greater than or equal to 1
  Warning  FailedDeployModel       46m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: ModifyTargetGroupAttributes, https response error StatusCode: 400, RequestID: 576d8b15-cf29-4774-bf52-8d81203e0e4c, api error ValidationError: Target group attribute key 'port' is not recognized
  Warning  FailedDeployModel       43m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: CreateTargetGroup, https response error StatusCode: 400, RequestID: 8a23ac34-7d58-4588-82d2-d756ffc7a61c, api error ValidationError: 1 validation error detected: Value '0' at 'port' failed to satisfy constraint: Member must have value greater than or equal to 1
  Warning  FailedDeployModel       35m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: CreateTargetGroup, https response error StatusCode: 400, RequestID: c65038de-7048-41ec-a28b-115f719de1f3, api error ValidationError: 1 validation error detected: Value '0' at 'port' failed to satisfy constraint: Member must have value greater than or equal to 1
  Warning  FailedDeployModel       33m                   ingress  Failed deploy model due to operation error Elastic Load Balancing v2: CreateTargetGroup, https response error StatusCode: 400, RequestID: 6d539b8a-9718-4d9a-8bd8-bac9065f9112, api error ValidationError: 1 validation error detected: Value '0' at 'port' failed to satisfy constraint: Member must have value greater than or equal to 1
  Normal   SuccessfullyReconciled  18m (x29 over 7h55m)  ingress  Successfully reconciled

[albertmorenomng]

Hello @ColeSu-n

What type os kubernetes cluster is deployed? EKS, Custom....

I have a similar situation using RKE2 cluster in AWS
(#3977)

Regards

[ColeSu-n]

Hello @ColeSu-n

What type os kubernetes cluster is deployed? EKS, Custom....

I have a similar situation using RKE2 cluster in AWS (#3977)

Regards

The company purchased the 1.31 version of k8s eks directly from AWS, and I think it may be that aws-loadbalance-controller lacks support for ExternalName type services

[shraddhabang]

@ColeSu-n We dont support ExternalName type svc yet. Also we dont support the cross namespace svc. Will you be able to use ClusterIP/NodePort type of svc meanwhile?

[ColeSu-n]

@ColeSu-n We dont support ExternalName type svc yet. Also we dont support the cross namespace svc. Will you be able to use ClusterIP/NodePort type of svc meanwhile?

@shraddhabang OK, thanks for your answer. I want to know why ExternalName svc is not supported? Because I found that nginx-ingress-controller and ingress-controller of other cloud vendors do not seem to support ExternalName svc either.

[zac-nixon]

Putting an ExternalName service behind a load balancer doesn't make a lot of sense nor is it supported. ALB / NLB will route traffic to an IP address. It looks like an ExternalName service is returning a DNS record.

This is just my basic understanding of reading:
https://stackoverflow.com/questions/54327697/kubernetes-externalname-services
https://kubernetes.io/docs/concepts/services-networking/service/#externalname

[zac-nixon]

Please re-open if you have other questions