Upgrade Ingress Handling to work with networkingv1/Ingress

docs/content/providers/kubernetes-ingress.md

@@ -6,6 +6,10 @@ The Kubernetes Ingress Controller.
 The Traefik Kubernetes Ingress provider is a Kubernetes Ingress controller; that is to say,
 it manages access to cluster services by supporting the [Ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/) specification.
 
+## Requirements
+
+Traefik supports `1.14+` Kubernetes clusters.
+
 ## Routing Configuration
 
 See the dedicated section in [routing](../routing/providers/kubernetes-ingress.md).
@@ -31,9 +35,9 @@ The provider then watches for incoming ingresses events, such as the example bel
 and derives the corresponding dynamic configuration from it,
 which in turn creates the resulting routers, services, handlers, etc.
 
-```yaml tab="File (YAML)"
+```yaml tab="Ingress"
 kind: Ingress
-apiVersion: extensions/v1beta1
+apiVersion: networking.k8s.io/v1beta1
 metadata:
   name: "foo"
   namespace: production
@@ -53,6 +57,32 @@ spec:
               servicePort: 80
 ```
 
+```yaml tab="Ingress Kubernetes v1.19+"
+kind: Ingress
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: "foo"
+  namespace: production
+
+spec:
+  rules:
+    - host: example.net
+      http:
+        paths:
+          - path: /bar
+            backend:
+              service:
+                name:  service1
+                port:
+                  number: 80
+          - path: /foo
+            backend:
+              service:
+                name:  service1
+                port:
+                  number: 80
+```
+
 ## LetsEncrypt Support with the Ingress Provider
 
 By design, Traefik is a stateless application,
@@ -220,7 +250,7 @@ Value of `kubernetes.io/ingress.class` annotation that identifies Ingress object
 If the parameter is set, only Ingresses containing an annotation with the same value are processed.
 Otherwise, Ingresses missing the annotation, having an empty value, or the value `traefik` are processed.
 
-!!! info "Kubernetes 1.18+"
+??? info "Kubernetes 1.18+"
 
     If the Kubernetes cluster version is 1.18+,
     the new `IngressClass` resource can be leveraged to identify Ingress objects that should be processed.
@@ -256,6 +286,39 @@ Otherwise, Ingresses missing the annotation, having an empty value, or the value
               servicePort: 80
     ```
 
+??? info "Kubernetes 1.19+"
+
+    If the Kubernetes cluster version is 1.19+,
+    prefer using the `networking.k8s.io/v1` [apiVersion](https://v1-19.docs.kubernetes.io/docs/setup/release/notes/#api-change) of `Ingress` and `IngressClass`.
+
+    ```yaml tab="IngressClass"
+    apiVersion: networking.k8s.io/v1
+    kind: IngressClass
+    metadata:
+      name: traefik-lb
+    spec:
+      controller: traefik.io/ingress-controller
+    ```
+
+    ```yaml tab="Ingress"
+    apiVersion: "networking.k8s.io/v1"
+    kind: "Ingress"
+    metadata:
+      name: "example-ingress"
+    spec:
+      ingressClassName: "traefik-lb"
+      rules:
+      - host: "*.example.com"
+        http:
+          paths:
+          - path: "/example"
+            backend:
+              service:
+                name: "example-service"
+                port:
+                    number: 80
+    ```
+
 ```toml tab="File (TOML)"
 [providers.kubernetesIngress]
   ingressClass = "traefik-internal"