Lowercase hostnames when used as node names in k8s

cluster/juju/layers/kubernetes-worker/reactive/kubernetes_worker.py

@@ -157,7 +157,7 @@ def shutdown():
     '''
     try:
         if os.path.isfile(kubeconfig_path):
-            kubectl('delete', 'node', gethostname())
+            kubectl('delete', 'node', gethostname().lower())
     except CalledProcessError:
         hookenv.log('Failed to unregister node.')
     service_stop('snap.kubelet.daemon')
@@ -906,7 +906,8 @@ class ApplyNodeLabelFailed(Exception):
 def _apply_node_label(label, delete=False, overwrite=False):
     ''' Invoke kubectl to apply node label changes '''
 
-    hostname = gethostname()
+    # k8s lowercases hostnames and uses them as node names
+    hostname = gethostname().lower()
     # TODO: Make this part of the kubectl calls instead of a special string
     cmd_base = 'kubectl --kubeconfig={0} label node {1} {2}'