Ability to use specific annotations with specific edns instance

[lexfrei]

What would you like to be added:
An option to mark annotations to be used with specific instance of edns.

Why is this needed:
In some cases, we need to use not just multiple providers, but different targets in each.
For example, I wanna create public dns and private dns for the same ingress to simplify routing.
Currently, I have these annotations:

    external-dns.alpha.kubernetes.io/target: "uuid.cfargotunnel.com"
    external-dns.alpha.kubernetes.io/cloudflare-proxied: "true"

but in the future I wanna use it like this:

    external-dns.alpha.kubernetes.io/target-cf: "uuid.cfargotunnel.com"
    external-dns.alpha.kubernetes.io/cloudflare-proxied-cf: "true"

    # or completely remove this to use ip from ingress status
    external-dns.alpha.kubernetes.io/target-local: "10.0.66.6"

Not just postfix can be used. The domain customization or prefix is fine too.

This looks very useful for multi instance usage of edns

[ivankatliarchuk]

You may need to share a bit more details to capture the idea. So you have different instances running one for each provider, what is the setup, which sources do you use, annotation examples?

Do you mind to create a guide for multi instance setup https://github.com/kubernetes-sigs/external-dns/tree/master/docs/tutorials?

[lexfrei]

@ivankatliarchuk, thanks for your feedback. I’d like to provide some additional context to clarify my proposal further.

Right now, I’m not running two separate external-dns deployments—even though I’d like to—because I don’t have a way to differentiate the annotations. The inability to parse custom, provider-specific annotations is a significant blocker for me.

My Current Situation:
• Single Deployment Limitation:
I currently run a single deployment since there’s no mechanism to assign different targets based on provider-specific annotations.
• Desired Setup:
Ideally, I’d like to run separate deployments for each provider (one for Cloudflare and one for Unifi). This way, each deployment would only process the annotations relevant to its provider. For example, I propose using a naming scheme that prepends the provider to the annotation key, such as:
• cf.external-dns.alpha.kubernetes.io/target for Cloudflare
• unifi.external-dns.alpha.kubernetes.io/target for Unifi

Why This Matters:

In my environment, Traefik is used to manage various endpoints based on specific routing rules. This approach lets me avoid the traditional method of running separate nginx-ingress instances for every case. I have endpoints that serve internal network requests (for Unifi) and an endpoint that manages a Cloudflare tunnel. With the proposed annotation mechanism, I could simply annotate my Ingress resources to automatically create both DNS records—one for the internal office and one for public access—without conflicting configurations.

I hope this additional detail clarifies my proposal. The current inability to parse custom annotations for different deployments is a blocker for me, and addressing it would greatly improve flexibility in multi-provider environments.