Tiller: listen on localhost by default

This change introduces a configuration option to control whether Tiller
listens on any IP addresses (the previous default), or binds only to
127.0.0.1 (the new default).

The same option is used for both the Armada and Tiller charts:
    .conf.tiller.listen_on_any (default: false)

The affected tiller command line argument is:
    -listen 127.0.0.1:port (if false)
    -listen :port (if true)

Listening on any address allows Helm client direct access to Tiller, via
'helm --host pod_ip:port'.

Listening on localhost does prevent connections directly to the pod IP,
but it does not preclude the use of 'kubectl port-forward' to establish
a connection to Tiller.

The Tiller container in the Armada pod exists only to service Armada via
127.0.0.1. The Helm client automatically sets up port forwarding (if it
has access to the Kubernetes API). As a result, this change should be
non-impacting. However, the previous behavior can be restored by setting
.conf.tiller.listen_on_any=true.

Change-Id: Id308976bac21cc521e8470516ce49ebd1942da68

charts/armada/templates/deployment-api.yaml

@@ -176,7 +176,7 @@ spec:
 {{- end }}
 {{- end }}
             - -listen
-            - ":{{ .Values.conf.tiller.port }}"
+            - "{{ if not .Values.conf.tiller.listen_on_any }}127.0.0.1{{ end }}:{{ .Values.conf.tiller.port }}"
             - -probe-listen
             - ":{{ .Values.conf.tiller.probe_port }}"
             - -logtostderr

charts/armada/values.yaml

@@ -206,6 +206,12 @@ conf:
   tiller:
     # If set to false then some form of Tiller needs to be provided
     enabled: true
+    # To have Tiller bind to all interfaces, allowing direct connections from
+    # the Helm client to pod_ip:port, set 'listen_on_any: true'.
+    # The default setting 'listen_on_any: false' binds Tiller to 127.0.0.1.
+    # The Armada container talks directly to Tiller via 127.0.0.1, so the
+    # default value is appropriate for normal operation.
+    listen_on_any: false
     port: 24134
     probe_port: 24135
     verbosity: 5

charts/tiller/templates/deployment-tiller.yaml

@@ -104,7 +104,7 @@ spec:
 {{- end }}
 {{- end }}
             - -listen
-            - ":{{ .Values.conf.tiller.port }}"
+            - "{{ if not .Values.conf.tiller.listen_on_any }}127.0.0.1{{ end }}:{{ .Values.conf.tiller.port }}"
             - -probe-listen
             - ":{{ .Values.conf.tiller.probe_port }}"
             - -logtostderr

charts/tiller/values.yaml

@@ -52,6 +52,12 @@ conf:
     # Note: Defaulting to the (default) kubernetes grace period, as anything
     # greater than that will have no effect.
     prestop_sleep: 30
+    # To have Tiller bind to all interfaces, allowing direct connections from
+    # the Helm client to pod_ip:port, set 'listen_on_any: true'.
+    # The default setting 'listen_on_any: false' binds Tiller to 127.0.0.1.
+    # Helm clients with Kubernetes API access dynamically set up a portforward
+    # into the pod, which works with the default setting.
+    listen_on_any: false
     port: 44134
     probe_port: 44135