Merge pull request #3185 from weaveworks/note-kube-dns

Note that WeaveDNS is disabled in Kubernetes addon

site/kubernetes/kube-addon.md

@@ -11,7 +11,9 @@ The following topics are discussed:
  * [Upgrading the Daemon Sets](#daemon-sets)
  * [CPU and Memory Requirements](#resources)
  * [Pod Eviction](#eviction)
-* [Network Policy Controller](#npc)
+* [Features](#features)
+ * [Pod Network](#pod-network)
+ * [Network Policy](#npc)
 * [Troubleshooting](#troubleshooting)
  * [Troubleshooting Blocked Connections](#blocked-connections)
  * [Things to watch out for](#key-points)
@@ -147,14 +149,31 @@ mypod-09vkd         0/1       Evicted   0          1h        <none>      node-1
 If you see this in your cluster, consider some of the above steps to
 reduce disruption.
 
-## <a name="npc"></a>Network Policy Controller
+## <a name="features"></a>Features
 
-The addon also supports the [Kubernetes policy
-API](http://kubernetes.io/docs/user-guide/networkpolicies/) so that
-you can securely isolate pods from each other based on namespaces and
+### <a name="pod-network"></a>Pod Network
+
+Weave Net provides a network to connect all pods together,
+implementing the [Kubernetes
+model](https://kubernetes.io/docs/concepts/cluster-administration/networking/#kubernetes-model).
+
+Kubernetes uses the _Container Network Interface_
+([CNI](https://github.com/containernetworking/cni)) to join pods onto Weave Net.
+
+Kubernetes implements many network features itself on top of the pod
+network.  This includes
+[Services](https://kubernetes.io/docs/concepts/services-networking/service/),
+[Service Discovery via DNS](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/)
+and [Ingress into the cluster](https://kubernetes.io/docs/concepts/services-networking/ingress/).
+WeaveDNS is disabled when using the Kubernetes addon.
+
+### <a name="npc"></a>Network Policy
+
+[Kubernetes Network Policies](https://kubernetes.io/docs/concepts/services-networking/network-policies/) let
+you securely isolate pods from each other based on namespaces and
 labels. For more information on configuring network policies in
 Kubernetes see the
-[walkthrough](http://kubernetes.io/docs/getting-started-guides/network-policy/walkthrough/)
+[walkthrough](https://kubernetes.io/docs/tasks/administer-cluster/declare-network-policy/)
 and the [NetworkPolicy API object
 definition](https://v1-7.docs.kubernetes.io/docs/api-reference/v1.7/#networkpolicy-v1-networking)
 
@@ -167,6 +186,11 @@ definition](https://v1-7.docs.kubernetes.io/docs/api-reference/v1.7/#networkpoli
 
 ## <a name="troubleshooting"></a> Troubleshooting
 
+Many Kubernetes network issues occur at a higher level than Weave Net.
+The [Kubernetes Service Debugging Guide]
+(https://kubernetes.io/docs/tasks/debug-application-cluster/debug-service/)
+has a detailed step-by-step guide.
+
 The status of Weave Net can be checked by running its CLI commands. This can be done in various ways:
 
 1\. [Install the `weave` script](/site/installing-weave.md) and run:

site/tasks/weavedns/weavedns.md

@@ -43,6 +43,10 @@ To disable an application container's use of weaveDNS, add the
 `--without-dns` option to `weave launch`. To
 disable weaveDNS itself, launch weave with the `--no-dns` option.
 
+> **Note** WeaveDNS is not part of the Weave Net Kubernetes add-on.
+    Kubernetes has its own DNS service, integrated with Kubernetes
+    Services, and WeaveDNS does not duplicate that functionality.
+
 **See Also**
 
  * [Integrating Docker via the API Proxy](/site/tasks/weave-docker-api/weave-docker-api.md)