Azure Provider not working for second level subdomains

[philipp-durrer-jarowa]

Name and Version

external-dns 0.15.0

What architecture are you using?

amd64

What steps will reproduce the bug?

1. Use the Azure integration, and have a DNS zone e.g. example.com
2. Try to create an ingress with an external-dns annotation for hostname: my.sub.example.com

Are you using any custom parameters or values?

provider: azure
azure:
    resourceGroup: "my-rg"
    tenantId: "XXXXX"
    subscriptionId: "XXXXX"
    useManagedIdentityExtension: true
txtOwnerId: "my-aks"
policy: sync # to cleanup old entries!
metrics:
  enabled: true
domainFilters:
- example.com

What is the expected behavior?

I expect external-dns to create a new A record my.sub. pointing to the ingress IP, since example.com is in the domainfilter list and my.sub.example.com is a valid domain it should be created in the Azure DNS Zone of example.com

What do you see instead?

external-dns is ignoring my.sub.example.com until I add sub.example.com to the domainfilters but then it obviously complains about the lack of subdns-zone sub.example.com (which I really don't want to create).

What I think is needed is to adapt the zoneMatchParent feature from the AWS provider for Azure so external-dns can create the two-level subdomain entry. Alternatively, the domainfilter logic could be more explicit and when *.example.com is set, to accept all subdomains of that domain. Or as a rather ugly alternative, there should be a domain -> zone map where I could say sub.example.com -> example.com