Prevent alarm created without scaling policy (#1448)

* refuse to create alarm without scaling policy

* add messages

deploy-board/deploy_board/templates/groups/asg_config.html

@@ -16,7 +16,6 @@
 {% include "groups/group_side_panel.html" %}
 </div>
 
-
 {% endblock %}
 
 {% block new-builds-panel %}
@@ -26,7 +25,14 @@
 
 {% block main %}
 
-
+{% if storage %}
+    {% for message in storage %}
+        <div class="alert alert-warning" role="alert">
+            <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+            <strong>Warning!</strong> {{ message | safe}}
+        </div>
+    {% endfor %}
+{% endif %}
 
 {% if not is_cmp %}
 <div id="launchConfigPid" class="panel panel-default">

deploy-board/deploy_board/webapp/group_view.py

@@ -20,6 +20,7 @@
 from django.template.loader import render_to_string
 from django.http import HttpResponse
 from django.contrib import messages
+from django.contrib.messages import get_messages
 import json
 import logging
 import traceback
@@ -794,6 +795,13 @@ def add_alarms(request, group_name):
             alarm_info["metricSource"] = params["awsMetrics"]
     alarm_info["groupName"] = group_name
 
+    if len(alarm_info["scalingPolicies"]) == 0:
+        # Technically, an alarm can be created without an action (e.g. scaling policy)
+        # However, in the current context, an alarm must have an associated scaling policy.
+        # In this case, there is no scaling policy, so refuse to create new alarm.
+        messages.add_message(request, messages.ERROR, 'Alarm could not be created because there was no {} policy.'.format(policy_type))
+        return redirect("/groups/{}/config/".format(group_name))
+
     autoscaling_groups_helper.add_alarm(request, group_name, [alarm_info])
 
     return redirect("/groups/{}/config/".format(group_name))
@@ -1180,6 +1188,7 @@ def get(self, request, group_name):
             "pas_config": pas_config,
             "is_cmp": is_cmp,
             "disallow_autoscaling": _disallow_autoscaling(curr_image),
+            "storage": get_messages(request)
         })