examples: update k8s examples

* Deprecate replication controller example and explain the reasons.

* Update statefulset controller example uncommenting StatefulSet Kind instead of
PetSet Kind

examples/kubernetes/README.md

@@ -5,7 +5,7 @@ Here you can find some examples on running stolon inside kubernetes
 There're two examples. The difference between them is how the keepers pods are deployed (the definitions of the other components is identical):
 
 * Using a [statefulset](statefulset) (called `petset` in k8s 1.4)
-* Using [replication controllers](rc) (one per keeper).
+* **DEPRECATED** Using [replication controllers](rc) (one per keeper).
 
 ## Docker image
 

examples/kubernetes/rc/README.md

@@ -1,5 +1,7 @@
 # Stolon inside kubernetes
 
+**DEPRECATED EXAMPLE**: Please use the [statefulset](../statefulset/README.md) example. Using persistent volumes with replication controller/replica sets won't guarantee at most once pod existence and can lead to data corruption with some persistent volume kind that can end attached in rw mode to more than one node at a time.
+
 This is a simple example that uses replication controller for all stolon components.
 
 Since the keeper requires a persistent data directory we define a replication controller with replicas=1 for each keeper. The keeper id is fixed inside the pod template definition so it won't be generated as a unique id but will have a more meaningful name (`keeper0`, `keeper1` etc...).

examples/kubernetes/statefulset/stolon-keeper.yaml

@@ -1,8 +1,8 @@
-# TODO(sgotti) update this to StatefulSet (PetSet where renamed to StatefulSet) when k8s 1.5 is released
-## apiVersion: apps/v1beta1
-## kind: StatefulSet
-apiVersion: apps/v1alpha1
-kind: PetSet
+# PetSet was renamed to StatefulSet in k8s 1.5
+# apiVersion: apps/v1alpha1
+# kind: PetSet
+apiVersion: apps/v1beta1
+kind: StatefulSet
 metadata:
   name: stolon-keeper
 spec:
@@ -48,7 +48,7 @@ spec:
             value: "stolon"
           - name: STKEEPER_PG_SU_PASSWORDFILE
             value: "/etc/secrets/stolon/password"
-          ## Uncomment this to enable debug logs
+          # Uncomment this to enable debug logs
           #- name: STKEEPER_DEBUG
           #  value: "true"
         ports:
@@ -62,13 +62,13 @@ spec:
         - name: stolon
           secret:
             secretName: stolon
-  ## Define your own volumeClaimTemplate. This example uses a dynamic provisioning with a storage class of type "anything" that works also with minikube and will provision volume using the hostPath provider, but this shouldn't be used in production and won't work in multi-node cluster.
-  ## In production you should use your own defined storage-class and configure your persistent volumes (statically or dynamic using a provisioner, see k8s doc).
+  # Define your own volumeClaimTemplate. This example uses dynamic PV provisioning with a storage class named "standard" (so it will works by default with minikube)
+  # In production you should use your own defined storage-class and configure your persistent volumes (statically or dynamically using a provisioner, see related k8s doc).
   volumeClaimTemplates:
   - metadata:
       name: data
       annotations:
-        volume.alpha.kubernetes.io/storage-class: anything
+        volume.alpha.kubernetes.io/storage-class: standard
     spec:
       accessModes: [ "ReadWriteOnce" ]
       resources: