Add Migration Guide for Traefik v2.1

docs/content/migration/v2.md

@@ -0,0 +1,99 @@
+# Migration: Steps needed between the versions
+
+## v2.0 to v2.1
+
+In v2.1, a new CRD called `TraefikService` was added. While updating an installation to v2.1,
+it is required to apply that CRD before as well as enhance the existing `ClusterRole` definition to allow Traefik to use that CRD.
+
+To add that CRD and enhance the permissions, following definitions need to be applied to the cluster.
+
+```yaml tab="TraefikService"
+apiVersion: apiextensions.k8s.io/v1beta1
+kind: CustomResourceDefinition
+metadata:
+  name: traefikservices.traefik.containo.us
+
+spec:
+  group: traefik.containo.us
+  version: v1alpha1
+  names:
+    kind: TraefikService
+    plural: traefikservices
+    singular: traefikservice
+  scope: Namespaced
+```
+
+```yaml tab="ClusterRole"
+kind: ClusterRole
+apiVersion: rbac.authorization.k8s.io/v1beta1
+metadata:
+  name: traefik-ingress-controller
+
+rules:
+  - apiGroups:
+      - ""
+    resources:
+      - services
+      - endpoints
+      - secrets
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - extensions
+    resources:
+      - ingresses
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - extensions
+    resources:
+      - ingresses/status
+    verbs:
+      - update
+  - apiGroups:
+      - traefik.containo.us
+    resources:
+      - middlewares
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - traefik.containo.us
+    resources:
+      - ingressroutes
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - traefik.containo.us
+    resources:
+      - ingressroutetcps
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - traefik.containo.us
+    resources:
+      - tlsoptions
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - traefik.containo.us
+    resources:
+      - traefikservices
+    verbs:
+      - get
+      - list
+      - watch
+```
+
+After having both resources applied, Traefik will work properly.

docs/mkdocs.yml

@@ -154,6 +154,7 @@ nav:
           - 'HTTP Challenge': 'user-guides/docker-compose/acme-http/index.md'
           - 'DNS Challenge': 'user-guides/docker-compose/acme-dns/index.md'
   - 'Migration':
+      - 'Traefik v2 minor migrations': 'migration/v2.md'
       - 'Traefik v1 to v2': 'migration/v1-to-v2.md'
   - 'Contributing':
       - 'Thank You!': 'contributing/thank-you.md'