Have DB setup warn about "localhost"

static/js/controllers/setup.js

@@ -3,6 +3,16 @@ function SetupCtrl($scope, $timeout, ApiService, Features, UserService, Containe
     return;
   }
 
+  $scope.HOSTNAME_REGEX = '^[a-zA-Z-0-9\.]+(:[0-9]+)?$';
+
+  $scope.validateHostname = function(hostname) {
+    if (hostname.indexOf('127.0.0.1') == 0 || hostname.indexOf('localhost') == 0) {
+      return 'Please specify a non-localhost hostname. "localhost" will refer to the container, not your machine.'
+    }
+
+    return null;
+  };
+
   // Note: The values of the enumeration are important for isStepFamily. For example,
   // *all* states under the "configuring db" family must start with "config-db".
   $scope.States = {

static/partials/setup.html

@@ -163,7 +163,9 @@
               <td>Database Server:</td>
               <td>
                 <span class="config-string-field" binding="fields.server"
-                      placeholder="dbserverhost"></span>
+                      placeholder="dbserverhost"
+                      pattern="{{ HOSTNAME_REGEX }}"
+                      validator="validateHostname(value)">></span>
                 <div class="help-text">
                   The server (and optionally, custom port) where the database lives
                 </div>