handle multiple ingresses of the same type

[jurgenweber]

I have and am using the standard nginx ingress controller on AWS.

Today I implemented a second one for using with a test and dev environments, mostly so I can test upgrading ingresses when I want to.

The problem I found is after moving the ingress to the new controller the dns did not move with it and I had to use:

external-dns.alpha.kubernetes.io/target:

not sure what the best implementation would be but can you use the annotation 'kubernetes.io/ingress.class' which is used to point an ingress to a controller to work it out?

I understand that using many controllers is actually quite common.

[hjacobs]

Good point, we should check how to support multiple ingress controllers. Do you have any suggestions? kubernetes.io/ingress.class is already used by the ingress controlllers, so I'm not sure whether External DNS should somehow respect/honor this annotation (or we need a new one?).

[jurgenweber]

I feel the respecting/honouring of 'kubernetes.io/ingress.class' is the best way to go. Makes it more automagic and less manual... and I see no reason to make it separate.

[mikkeloscar]

But how do you handle the case where you have two ingress controllers and you want an ingress to be controlled by a particular ingress controller AND external-dns? Or is kubernetes.io/ingress.class supposed to handle a list as value?

[jurgenweber]

well.. that would be the normal behaviour.......

ingress using ingress controller one with external dns:

    external-dns.alpha.kubernetes.io/controller: "dns-controller"
    kubernetes.io/ingress.class: "nginx-test"

ingress using ingress controller two with external dns:

    external-dns.alpha.kubernetes.io/controller: "dns-controller"
    kubernetes.io/ingress.class: "nginx"

ingress using ingress controller 3, without external dns:

    kubernetes.io/ingress.class: "yet-another-nginx"

I understand there are plans afoot to change the external-dns annotation. #111

[mikkeloscar]

It sounds like what you want is a way to tell external-dns to only operate on ingresses which has the annotation: external-dns.alpha.kubernetes.io/controller: "dns-controller" specified or do I misunderstand you?

This seems reasonable to add as a flag (It should not be default as it's annoying to have to add the annotation everywhere in case you only have ingresses that should be managed by external-dns.)

[jurgenweber]

isn't this the current behaviour? It is what I had to do to make it work. As per this; #111 Sounds like the feature is already there.

[mikkeloscar]

Right now, having no annotation is the same as having external-dns.alpha.kubernetes.io/controller: "dns-controller".
So if you have two ingress resources, one for each ingress controller (but using the same hostname), then you would need to put something like external-dns.alpha.kubernetes.io/controller: "not-external-dns" to ensure that external-dns only creates an entry for one ingress resource (the one without the annotation).

This is how I understand your issue. If this is wrong, please elaborate.

[jurgenweber]

I outline the idea/issue in the original post.
This could cover one edge case, not sure why you would want it thou.

[mikkeloscar]

@jurgenweber would #354 solve your problem?

[jurgenweber]

Looks like it! Awesome stuff.

[hjacobs]

Closing this as #354 (generic --annotation-filter support) was released in v0.4.8.