First cut at adding documentation for accessing the cluster

docs/accessing-the-cluster.md

+# Accessing the Cluster
+
+## Using the Kubernetes proxy to access the cluster
+Information about the cluster can be accessed by using a proxy URL and by providing the keys to the cluster.
+For example, for a cluster that has cluster-level logging enabled using Elasticsearch you can fetch information about
+the Elasticsearch logging cluster.
+
+First, you will need to obtain the keys (username and password) for your cluster:
+
+```
+$ cat ~/.kube/kubernetes-satnam2_kubernetes/kubernetes_auth
+{
+  "User": "admin",
+  "Password": "4mty0Vl9nNFfwLJz",
+  "CAFile": "/Users/satnam/.kube/kubernetes-satnam2_kubernetes/kubernetes.ca.crt",
+  "CertFile": "/Users/satnam/.kube/kubernetes-satnam2_kubernetes/kubecfg.crt",
+  "KeyFile": "/Users/satnam/.kube/kubernetes-satnam2_kubernetes/kubecfg.key"
+}
+```
+
+To access a service endpoint `/alpha/beta/gamma/` via the proxy service for your service `myservice` you need to specify an HTTPS address
+for the Kubernetes master followed by `/api/v1beta1/proxy/services/myservice/alpha/beta/gamma/`. Currently it is important to
+specify the trailing `/`.
+
+Here is a list of representative cluster-level system services:
+```
+$ kubectl get services --selector="kubernetes.io/cluster-service=true"
+NAME                    LABELS                                                          SELECTOR                     IP                  PORT
+elasticsearch-logging   kubernetes.io/cluster-service=true,name=elasticsearch-logging   name=elasticsearch-logging   10.0.251.46         9200
+kibana-logging          kubernetes.io/cluster-service=true,name=kibana-logging          name=kibana-logging          10.0.118.199        5601
+kube-dns                k8s-app=kube-dns,kubernetes.io/cluster-service=true             k8s-app=kube-dns             10.0.0.10           53
+monitoring-grafana      kubernetes.io/cluster-service=true,name=grafana                 name=influxGrafana           10.0.15.119         80
+monitoring-heapster     kubernetes.io/cluster-service=true,name=heapster                name=heapster                10.0.101.222        80
+monitoring-influxdb     kubernetes.io/cluster-service=true,name=influxdb                name=influxGrafana           10.0.155.212        80
+```
+
+Using this information you can now issue the following `curl` command to get status information about
+the Elasticsearch logging service.
+```
+$ curl -k -u admin:4mty0Vl9nNFfwLJz https://104.197.5.247/api/v1beta1/proxy/services/elasticsearch-logging/
+{
+  "status" : 200,
+  "name" : "Senator Robert Kelly",
+  "cluster_name" : "kubernetes_logging",
+  "version" : {
+    "number" : "1.4.4",
+    "build_hash" : "c88f77ffc81301dfa9dfd81ca2232f09588bd512",
+    "build_timestamp" : "2015-02-19T13:05:36Z",
+    "build_snapshot" : false,
+    "lucene_version" : "4.10.3"
+  },
+  "tagline" : "You Know, for Search"
+}
+```
+
+You can provide a suffix and parameters:
+```
+$ curl -k -u admin:4mty0Vl9nNFfwLJz https://104.197.5.247/api/v1beta1/proxy/services/elasticsearch-logging/_cluster/health?pretty=true
+{
+  "cluster_name" : "kubernetes_logging",
+  "status" : "yellow",
+  "timed_out" : false,
+  "number_of_nodes" : 1,
+  "number_of_data_nodes" : 1,
+  "active_primary_shards" : 5,
+  "active_shards" : 5,
+  "relocating_shards" : 0,
+  "initializing_shards" : 0,
+  "unassigned_shards" : 5
+}
+```
+
+You can also visit the endpoint of a service via the proxy URL e.g.
+```
+https://104.197.5.247/api/v1beta1/proxy/services/kibana-logging/
+```
+The first time you access the cluster using a proxy address from a browser you will be prompted
+for a username and password which can also be found in the `User` and `Password` fields of the `kubernetes_auth`
+file.