Simplify sample inventory

- The bastion is not needed for a simple example
- All is implicit we can just define our host in groups directly

inventory/sample/inventory.ini

@@ -1,31 +1,20 @@
-# ## Configure 'ip' variable to bind kubernetes services on a
-# ## different ip than the default iface
-# ## We should set etcd_member_name for etcd cluster. The node that is not a etcd member do not need to set the value, or can set the empty string value.
-[all]
+# This inventory describe a HA typology with stacked etcd (== same nodes as control plane)
+# and 3 worker nodes
+# See https://docs.ansible.com/ansible/latest/inventory_guide/intro_inventory.html
+# for tips on building your # inventory
+
+# Configure 'ip' variable to bind kubernetes services on a different ip than the default iface
+# We should set etcd_member_name for etcd cluster. The node that are not etcd members do not need to set the value,
+# or can set the empty string value.
+[kube_control_plane]
 # node1 ansible_host=95.54.0.12  # ip=10.3.0.1 etcd_member_name=etcd1
 # node2 ansible_host=95.54.0.13  # ip=10.3.0.2 etcd_member_name=etcd2
 # node3 ansible_host=95.54.0.14  # ip=10.3.0.3 etcd_member_name=etcd3
-# node4 ansible_host=95.54.0.15  # ip=10.3.0.4 etcd_member_name=etcd4
-# node5 ansible_host=95.54.0.16  # ip=10.3.0.5 etcd_member_name=etcd5
-# node6 ansible_host=95.54.0.17  # ip=10.3.0.6 etcd_member_name=etcd6
-
-# ## configure a bastion host if your nodes are not directly reachable
-# [bastion]
-# bastion ansible_host=x.x.x.x ansible_user=some_user
-
-[kube_control_plane]
-# node1
-# node2
-# node3
 
-[etcd]
-# node1
-# node2
-# node3
+[etcd:children]
+kube_control_plane
 
 [kube_node]
-# node2
-# node3
-# node4
-# node5
-# node6
+# node4 ansible_host=95.54.0.15  # ip=10.3.0.4
+# node5 ansible_host=95.54.0.16  # ip=10.3.0.5
+# node6 ansible_host=95.54.0.17  # ip=10.3.0.6