Failed to use --source=ambassador-host with 3.X emissary branch versions

[jordanefillatre]

What happened:

Running external dns in latest version

E0807 14:46:06.754231       1 reflector.go:200] "Failed to watch" err="failed to list getambassador.io/v2, Resource=hosts: the server could not find the requested resource" logger="UnhandledError" reflector="k8s.io/client-go@v0.33.2/tools/cache/reflector.go:285" type="getambassador.io/v2, Resource=hosts"   

What you expected to happen:

The controller is able to use Host resource annotations to create DNS entries
How to reproduce it (as minimally and precisely as possible):

I use the v3alpha1 version of the ambassador api

apiVersion: getambassador.io/v3alpha1
kind: Host
metadata:
  name: mydomain
  namespace: emissary
  annotations:
    external-dns.ambassador-service: emissary-emissary-ingress.emissary
spec:
  acmeProvider:
    authority: none
  hostname:  example.com
  tlsSecret:
    name: ambassador-certs

Anything else we need to know?:
It works with old 2.5.1 version of emissary
Environment:

• External-DNS version (use external-dns --version): 0.18.0
• DNS provider: route53
• Others:

[ivankatliarchuk]

Feel free to open a PR. How to contribute https://github.com/kubernetes-sigs/external-dns/blob/master/docs/contributing/index.md#developer-documentations-advanced-topics

What is required, evidences that is working on real cluster. Example recent istio bump #5611