[Bug]: DNSEndpoint recordType is incorrect for dual-stack services

[bj0rn]

Version

edge

What Kubernetes platforms are you running on?

AKS Azure

Steps to reproduce

When using a dual-stack LoadBalancer Service, the NGINX Ingress Controller generates an invalid DNSEndpoint.

Instead of creating separate DNS records for IPv4 (A) and IPv6 (AAAA), a single A record is created with both IPv4 and IPv6 addresses as targets.

Actual behavior:

apiVersion: externaldns.nginx.org/v1
kind: DNSEndpoint
metadata:
  name: podinfo.example.com
  namespace: podinfo
spec:
  endpoints:
    - dnsName: podinfo.example.com
      recordType: A
      targets:
        - 127.0.0.1
        - ::1

Expected behavior:

apiVersion: externaldns.nginx.org/v1
kind: DNSEndpoint
metadata:
  name: podinfo.example.com
  namespace: podinfo
spec:
  endpoints:
    - dnsName: podinfo.example.com
      recordType: A
      targets:
        - 127.0.0.1
    - dnsName: podinfo.example.com
      recordType: AAAA
      targets:
        - ::1

[github-actions]

Hi @bj0rn thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!

[javorszky]

Hey @bj0rn,

Thank you for the report. I managed to reproduce the issue, you're correct, it's a bug. We'll add it to planning.

The issue

In the getValidTargets function the incoming slice of ExternalEndpoints entries are iterated over, their IP / Hostnames parsed, and the single target string slice gets populated, and the type of the last entry wins.

There's a test to make sure that's actually what happens: https://github.com/nginx/kubernetes-ingress/blob/main/internal/externaldns/sync_test.go#L64-L76

Both the function and the test are incorrect though, the desired functionality is that multiple types of targets returned grouped by their types (A, AAAA, CNAME)