Add instructions to check weave-kube logs

"Check it is running" and "check the logs" are important steps when
troubleshooting.

site/kubernetes/kube-addon.md

@@ -186,12 +186,42 @@ definition](https://v1-7.docs.kubernetes.io/docs/api-reference/v1.7/#networkpoli
 
 ## <a name="troubleshooting"></a> Troubleshooting
 
+The first thing to check is whether the Weave Net software is up and
+running. The `kubectl apply` command you use to install only
+_requests_ that it be downloaded and started; if anything goes wrong
+at startup the details will only be visible in the logs of the container(s).
+
+To check what is running:
+
+```
+$ kubectl get pods -n kube-system -l name=weave-net
+NAME              READY  STATUS   RESTARTS  AGE
+weave-net-1jkl6   2/2    Running  0         1d
+weave-net-bskbv   2/2    Running  0         1d
+weave-net-m4x1b   2/2    Running  0         1d
+```
+
+You should see one line for each node in your cluster; each line
+should have STATUS "Running", and READY should be 2 out of 2.
+
+If you see a STATUS like "Error" or "CrashLoopBackoff", look in the
+logs. Pick one of the pods with that status from the list and ask for
+the logs like this:
+
+```
+$ kubectl logs -n kube-system weave-net-1jkl6 weave
+```
+
+You can pipe the output into a file for easier viewing, especially if
+it is long.
+
 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:
+Once it is up and running, 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: