docs: replace mentions of ingress.class annotations for the spec.ingressClassName field

docs/faq.md

@@ -257,8 +257,7 @@ spec:
 ### Running an internal and external dns service
 
 Sometimes you need to run an internal and an external dns service.
-The internal one should provision hostnames used on the internal network (perhaps inside a VPC), and the external
-one to expose DNS to the internet.
+The internal one should provision hostnames used on the internal network (perhaps inside a VPC), and the external one to expose DNS to the internet.
 
 To do this with ExternalDNS you can use the `--ingress-class` flag to specifically tie an instance of ExternalDNS to an instance of a ingress controller. 
 Let's assume you have two ingress controllers, `nginx-internal` and `nginx-external`.
@@ -267,16 +266,21 @@ You can then start two ExternalDNS providers, one with `--ingress-class=nginx-in
 If you need to search for multiple ingress classes, you can specify the flag multiple times, like so:
 `--ingress-class=nginx-internal --ingress-class=alb-ingress-internal`.
 
-The `--ingress-class` flag will check both the `ingressClassName` field and the deprecated `kubernetes.io/ingress.class` annotation.
+The `--ingress-class` flag will check both the `spec.ingressClassName` field and the deprecated `kubernetes.io/ingress.class` annotation.
+The `spec.ingressClassName` tasks precedence over the annotation if both are supplied.
 
-Note: the `--ingress-class` flag cannot be used at the same time as a `kubernetes.io/ingress.class` annotation filter; if you do this an error will be raised.
+**Backward compatibility**
 
-If you use annotations to indicate different ingress classes in your cluster, you can instead use an `--annotation-filter` flag to restrict which objects ExternalDNS considers; for example, `--annotation-filter=kubernetes.io/ingress.class in (public,dmz)`.
+The previous `--annotation-filter` flag can still be used to restrict which objects ExternalDNS considers; for example, `--annotation-filter=kubernetes.io/ingress.class in (public,dmz)`.
 
 However, beware when using annotation filters with multiple sources, e.g. `--source=service --source=ingress`, since `--annotation-filter` will filter every given source object.
 If you need to use annotation filters against a specific source you have to run a separated external dns service containing only the wanted `--source`  and `--annotation-filter`.
 
-**Note:** Filtering based on annotation or ingress class name means that the external-dns controller will receive all resources of that kind and then filter on the client-side.
+Note: the `--ingress-class` flag cannot be used at the same time as the `--annotation-filter=kubernetes.io/ingress.class in (...)` flag; if you do this an error will be raised.
+
+**Performance considerations**
+
+Filtering based on ingress class name or annotations means that the external-dns controller will receive all resources of that kind and then filter on the client-side.
 In larger clusters with many resources which change frequently this can cause performance issues. 
 If only some resources need to be managed by an instance of external-dns then label filtering can be used instead of ingress class filtering (or legacy annotation filtering). 
 This means that only those resources which match the selector specified in `--label-filter` will be passed to the controller.

docs/tutorials/alibabacloud.md

@@ -233,9 +233,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: foo
-  annotations:
-    kubernetes.io/ingress.class: "nginx" # use the one that corresponds to your ingress controller.
 spec:
+  ingressClassName: nginx # use the one that corresponds to your ingress controller.
   rules:
   - host: foo.external-dns-test.com
     http:

docs/tutorials/aws-load-balancer-controller.md

@@ -24,7 +24,7 @@ as Kubernetes does with the AWS cloud provider.
 In the examples that follow, it is assumed that you configured the ALB Ingress
 Controller with the `ingress-class=alb` argument (not to be confused with the
 same argument to ExternalDNS) so that the controller will only respect Ingress
-objects with the `kubernetes.io/ingress.class` annotation set to "alb".
+objects with the `ingressClassName` field set to "alb".
 
 ## Deploy an example application
 
@@ -80,7 +80,6 @@ kind: Ingress
 metadata:
   annotations:
     alb.ingress.kubernetes.io/scheme: internet-facing
-    kubernetes.io/ingress.class: alb
   name: echoserver
 spec:
   ingressClassName: alb
@@ -120,7 +119,6 @@ metadata:
   annotations:
     alb.ingress.kubernetes.io/scheme: internet-facing
     external-dns.alpha.kubernetes.io/hostname: echoserver.mycluster.example.org, echoserver.example.org
-    kubernetes.io/ingress.class: alb
   name: echoserver
 spec:
   ingressClassName: alb
@@ -159,7 +157,6 @@ metadata:
   annotations:
     alb.ingress.kubernetes.io/scheme: internet-facing
     alb.ingress.kubernetes.io/ip-address-type: dualstack
-    kubernetes.io/ingress.class: alb
   name: echoserver
 spec:
   ingressClassName: alb

docs/tutorials/aws.md

@@ -739,9 +739,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: "nginx" # use the one that corresponds to your ingress controller.
 spec:
+  ingressClassName: nginx
   rules:
     - host: server.example.com
       http:
@@ -936,7 +935,8 @@ Running several fast polling ExternalDNS instances in a given account can easily
   * `--source=ingress --source=service` - specify multiple times for multiple sources
   * `--namespace=my-app`
   * `--label-filter=app in (my-app)`
-  * `--annotation-filter=kubernetes.io/ingress.class in (nginx-external)` - note that this filter would apply to services too..
+  * `--ingress-class=nginx-external`
+  * `--annotation-filter=kubernetes.io/ingress.class in (nginx-external)` - note that this filter would apply to services too.. (deprecated in favor of `--ingress-class`)
 * Limit services watched by type (not applicable to ingress or other types)
   * `--service-type-filter=LoadBalancer` default `all`
 * Limit the hosted zones considered

docs/tutorials/azure-private-dns.md

@@ -416,9 +416,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: nginx
 spec:
+  ingressClassName: nginx
   rules:
   - host: server.example.com
     http:

docs/tutorials/coredns.md

@@ -198,9 +198,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: "nginx"
 spec:
+  ingressClassName: nginx
   rules:
   - host: nginx.example.org
     http:

docs/tutorials/exoscale.md

@@ -109,9 +109,9 @@ kind: Ingress
 metadata:
   name: nginx
   annotations:
-    kubernetes.io/ingress.class: nginx
     external-dns.alpha.kubernetes.io/target: {{ Elastic-IP-address }}
 spec:
+  ingressClassName: nginx
   rules:
   - host: via-ingress.example.com
     http:

docs/tutorials/kube-ingress-aws.md

@@ -141,8 +141,6 @@ Create the following Ingress to expose the echoserver application to the Interne
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
-  annotations:
-    kubernetes.io/ingress.class: skipper
   name: echoserver
 spec:
   ingressClassName: skipper
@@ -181,7 +179,6 @@ kind: Ingress
 metadata:
   annotations:
     external-dns.alpha.kubernetes.io/hostname: echoserver.mycluster.example.org, echoserver.example.org
-    kubernetes.io/ingress.class: skipper
   name: echoserver
 spec:
   ingressClassName: skipper
@@ -218,7 +215,6 @@ kind: Ingress
 metadata:
   annotations:
     alb.ingress.kubernetes.io/ip-address-type: dualstack
-    kubernetes.io/ingress.class: skipper
   name: echoserver
 spec:
   ingressClassName: skipper
@@ -256,7 +252,6 @@ kind: Ingress
 metadata:
   annotations:
     zalando.org/aws-load-balancer-type: nlb
-    kubernetes.io/ingress.class: skipper
   name: echoserver
 spec:
   ingressClassName: skipper

docs/tutorials/nginx-ingress.md

@@ -294,8 +294,6 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: nginx
 spec:
   ingressClassName: nginx
   rules:
@@ -595,8 +593,6 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: nginx
 spec:
   ingressClassName: nginx
   rules:

docs/tutorials/public-private-route53.md

@@ -213,7 +213,7 @@ spec:
 
 Consult [AWS ExternalDNS setup docs](aws.md) for installation guidelines.
 
-In ExternalDNS containers args, make sure to specify `aws-zone-type` and either `ingress-class` or `annotation-filter` (depending on whether your cluster makes use of `ingressClassName`):
+In ExternalDNS containers args, make sure to specify `aws-zone-type` and `ingress-class`:
 
 ```yaml
 apiVersion: apps/v1beta2
@@ -251,7 +251,7 @@ spec:
 
 Consult [AWS ExternalDNS setup docs](aws.md) for installation guidelines.
 
-In ExternalDNS containers args, make sure to specify `aws-zone-type` and either `ingress-class` or `annotation-filter` (depending on whether your cluster makes use of `ingressClassName`):
+In ExternalDNS containers args, make sure to specify `aws-zone-type` and `ingress-class`:
 
 ```yaml
 apiVersion: apps/v1beta2
@@ -280,8 +280,6 @@ spec:
         - --registry=txt
         - --txt-owner-id=dev.k8s.nexus
         - --ingress-class=internal-ingress
-        # ... or, if you use annotations for ingress classes
-        # - --annotation-filter=kubernetes.io/ingress.class in (internal-ingress)
         - --aws-zone-type=private
         image: registry.k8s.io/external-dns/external-dns:v0.13.4
         name: external-dns-private
@@ -291,21 +289,17 @@ spec:
 
 For this setup to work, you need to create two Ingress definitions for your application.
 
-At first, create a public Ingress definition (make sure to un-comment either the `annotations` or `ingressClassName` lines):
+At first, create a public Ingress definition:
 
 ```yaml
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
-  # uncomment if you use annotations for ingress classes
-  # annotations:
-  #   kubernetes.io/ingress.class: "external-ingress"
   labels:
     app: app
   name: app-public
 spec:
-  # uncomment if you use ingressClassName
-  # ingressClassName: external-ingress
+  ingressClassName: external-ingress
   rules:
   - host: app.domain.com
     http:
@@ -318,21 +312,17 @@ spec:
         pathType: Prefix
 ```
 
-Then create a private Ingress definition (again, make sure to un-comment either the `annotations` or `ingressClassName` lines):
+Then create a private Ingress definition:
 
 ```yaml
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
-  # uncomment if you use annotations for ingress classes
-  # annotations:
-  #   kubernetes.io/ingress.class: "internal-ingress"
   labels:
     app: app
   name: app-private
 spec:
-  # uncomment if you use ingressClassName
-  # ingressClassName: internal-ingress
+  ingressClassName: internal-ingress
   rules:
   - host: app.domain.com
     http:

docs/tutorials/rdns.md

@@ -142,9 +142,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: nginx
-  annotations:
-    kubernetes.io/ingress.class: "nginx"
 spec:
+  ingressClassName: nginx
   rules:
   - host: nginx.lb.rancher.cloud
     http: