add guess button for cloned instance name. this reads dhcp conf and uses settings.CLONE_INSTANCE_DEFAULT_PREFIX.

instances/templates/instance.html

@@ -713,17 +713,23 @@
                                                     <form class="form-horizontal" action="" method="post" role="form">{% csrf_token %}
                                                         <div class="form-group">
                                                             <label class="col-sm-3 control-label" style="font-weight:normal;">{% trans "Clone Name" %}</label>
+                                                            {% if request.user.is_superuser %}
                                                             <div class="col-sm-4">
-                                                                {% if request.user.is_superuser %}
                                                                 <input id="clone_name" type="text" class="form-control" name="name" value="{{ vname }}-clone"/>
-                                                                {% else %}
+                                                            </div>
+                                                            <div class="col-sm-4">
+                                                                <button type="button" class="btn btn-sm btn-success pull-left" name="guess-clone-name"
+                                                                        onclick="guess_clone_name()" style="margin-top: 2px;">{% trans "Guess" %}</button>
+                                                            </div>
+                                                            {% else %}
+                                                            <div class="col-sm-4">
                                                                 <select id="select_clone_name" class="form-control" name="name" size="1"/>
                                                                 {% for name in clone_free_names %}
                                                                     <option value="{{ name }}">{{ name }}</option>
                                                                 {% endfor %}
                                                                 </select>
-                                                                {% endif %}
                                                             </div>
+                                                            {% endif %}
                                                         </div>
                                                         {% if request.user.is_superuser %}
                                                             <p style="font-weight:bold;">{% trans "Network devices" %}</p>
@@ -1040,6 +1046,15 @@
         });
     }
 </script>
+<script>
+    function guess_clone_name() {
+        $.getJSON('/instance/guess_clone_name/', function(data) {
+            guessed_name = data['name'].split(".")[0];
+            $('#clone_name').val(guessed_name);
+            update_clone_disk_name(guessed_name);
+        });
+    }
+</script>
 <script>
     function update_clone_disk_name(new_vname) {
         vname = '{{ vname }}-clone';

instances/urls.py

@@ -10,6 +10,8 @@ urlpatterns = [
         views.inst_status, name='inst_status'),
     url(r'^guess_mac_address/(?P<vname>[\w\-\.]+)/$',
         views.guess_mac_address, name='guess_mac_address'),
+    url(r'^guess_clone_name/$',
+        views.guess_clone_name, name='guess_clone_name'),
     url(r'^check_instance/(?P<vname>[\w\-\.]+)/$',
         views.check_instance, name='check_instance'),
 ]

instances/views.py

@@ -780,6 +780,21 @@ def guess_mac_address(request, vname):
                     break
     return HttpResponse(json.dumps(data));
 
+@login_required
+def guess_clone_name(request):
+    dhcp_file = '/srv/webvirtcloud/dhcpd.conf'
+    prefix = settings.CLONE_INSTANCE_DEFAULT_PREFIX
+    if os.path.isfile(dhcp_file):
+        instance_names = [i.name for i in Instance.objects.filter(name__startswith=prefix)]
+        with open(dhcp_file, 'r') as f:
+            for line in f:
+                line = line.strip()
+                if "host %s" % prefix in line:
+                    hostname = line.split(' ')[1]
+                    if hostname.startswith(prefix) and hostname not in instance_names:
+                        return HttpResponse(json.dumps({'name': hostname}))
+    return HttpResponse(json.dumps({}));
+
 @login_required
 def check_instance(request, vname):
     check_instance = Instance.objects.filter(name=vname)