Adding support for changing default backend and nginx container images

cluster/juju/layers/kubernetes-worker/config.yaml

@@ -58,3 +58,15 @@ options:
 
       The value for this config must be a JSON array of credential objects, like this:
         [{"server": "my.registry", "username": "myUser", "password": "myPass"}]
+  nginx-image:
+    type: string
+    default: "auto"
+    description: |
+      Docker image to use for the nginx ingress controller. Auto will select an image
+      based on architecture.
+  default-backend-image:
+    type: string
+    default: "auto"
+    description: |
+      Docker image to use for the default backend. Auto will select an image
+      based on architecture.

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

@@ -624,17 +624,28 @@ def create_kubeconfig(kubeconfig, server, ca, key=None, certificate=None,
     check_call(split(cmd.format(kubeconfig, context)))
 
 
+@when_any('config.changed.default-backend-image',
+          'config.changed.nginx-image')
 def launch_default_ingress_controller():
     ''' Launch the Kubernetes ingress controller & default backend (404) '''
+    config = hookenv.config()
+
+    # need to test this in case we get in here from a config change to the image
+    if not config.get('ingress'):
+        return
+    
     context = {}
     context['arch'] = arch()
     addon_path = '/root/cdk/addons/{}'
 
-    context['defaultbackend_image'] = \
-        "gcr.io/google_containers/defaultbackend:1.4"
-    if arch() == 's390x':
-        context['defaultbackend_image'] = \
-            "gcr.io/google_containers/defaultbackend-s390x:1.4"
+    context['defaultbackend_image'] = config.get('default-backend-image')
+    if context['defaultbackend_image'] == "" or context['defaultbackend_image'] == "auto":
+        if context['arch'] == 's390x':
+            context['defaultbackend_image'] = \
+                "gcr.io/google_containers/defaultbackend-s390x:1.4"
+        else:
+            context['defaultbackend_image'] = \
+                "gcr.io/google_containers/defaultbackend:1.4"
 
     # Render the default http backend (404) replicationcontroller manifest
     manifest = addon_path.format('default-http-backend.yaml')
@@ -650,11 +661,14 @@ def launch_default_ingress_controller():
         return
 
     # Render the ingress daemon set controller manifest
-    context['ingress_image'] = \
-        "gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.13"
-    if arch() == 's390x':
-        context['ingress_image'] = \
-            "docker.io/cdkbot/nginx-ingress-controller-s390x:0.9.0-beta.13"
+    context['ingress_image'] = config.get('nginx-image')
+    if context['ingress_image'] == "" or context['ingress_image'] == "auto":
+        if context['arch'] == 's390x':
+            context['ingress_image'] = \
+                "docker.io/cdkbot/nginx-ingress-controller-s390x:0.9.0-beta.13"
+        else:
+            context['ingress_image'] = \
+                "gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.15"
     context['juju_application'] = hookenv.service_name()
     manifest = addon_path.format('ingress-daemon-set.yaml')
     render('ingress-daemon-set.yaml', manifest, context)