Feature to resolve Ingress source hostnames to IP

[mhanc]

What would you like to be added: Feature to resolve Ingress status.loadBalancer.ingress[0].hostname to IP, same as existing flag --resolve-service-load-balancer-hostname.

Why is this needed: To create A records instead of CNAME records for hostnames like 10.200.1.1.nip.io.

The Ingress status value status.loadBalancer.ingress[0].hostname can contain a nip.io FQDN like 10.200.1.1.nip.io in some ingress-nginx configurations, which leads to using nip.io CNAMEs instead of A records. This works correctly, as external-dns creates a CNAME record. However, having external-dns resolve this to an IP and create an A record would simplify the setup and not require resolving .nip.io records.

Example Ingress status:

apiVersion: networking.k8s.io/v1
kind: Ingress
  name: my-ingress
spec:
  ingressClassName: nginx
  rules:
  - host: example.org
    http:
      paths:
      - backend:
          service:
            name: example-service
            port:
              name: http
        path: /
        pathType: Prefix
status:
  loadBalancer:
    ingress:
    - hostname: 10.200.130.84.nip.io

external-dns in this case will create a CNAME record from example.org to 10.200.130.84.nip.io. This feature request is to resolve the hostname 10.200.130.84.nip.io to 10.200.130.84 and so create an example.org A record pointing to 10.200.130.84.

[hjoshi123]

This does seem a valid scenario to be implemented.. @mhanc is it just nip.io that you are thinking of or is there any other usecase you can think of for the flag you are requesting?
/assign

[hjoshi123]

@ivankatliarchuk needed your take on this.. do you think this is within the scope of ex-dns?

[mhanc]

@hjoshi123 As far as I know, only .nip.io addresses are used, but my view is limited to our Kubernetes clusters. I also dont have information, how this works with IPv6 or similar. However, I think that doing just DNS resolution would cover any other hostname values.

[ivankatliarchuk]

nip.io relates to powerdns. Could you share your arguments as well, not helm pls.

We need someone who familiar with powerdns, most likely have access or account there and able to reproduce the problem. I've no clue how pdns provider should behave.