Update to Kubernetes v1.7.3 (#1549)

Change kubelet deploy mode to host
Enable cri and qos per cgroup for kubelet
Update CoreOS images
Add upgrade hook for switching from kubelet deployment from docker to host.
Bump machine type for ubuntu-rkt-sep

roles/kubernetes/node/defaults/main.yml

@@ -1,5 +1,5 @@
 # Valid options: docker (default), rkt, or host
-kubelet_deployment_type: docker
+kubelet_deployment_type: host
 
 # change to 0.0.0.0 to enable insecure access from anywhere (not recommended)
 kube_apiserver_insecure_bind_address: 127.0.0.1
@@ -15,8 +15,8 @@ kube_proxy_masquerade_all: false
 
 # These options reflect limitations of running kubelet in a container.
 # Modify at your own risk
-kubelet_enable_cri: false
-kubelet_cgroups_per_qos: false
+kubelet_enable_cri: true
+kubelet_cgroups_per_qos: true
 # Set to empty to avoid cgroup creation
 kubelet_enforce_node_allocatable: "\"\""
 

roles/kubernetes/node/tasks/pre_upgrade.yml

@@ -4,3 +4,8 @@
   args:
     creates: "/var/lib/cni"
   failed_when: false
+
+- name: "Pre-upgrade | ensure kubelet container is stopped if using host deployment"
+  command: docker stop kubelet
+  failed_when: false
+  when: kubelet_deployment_type == "host"