Color the border of essential services in the status page bottom section

zoe_api/web/static/zoe.css

@@ -243,6 +243,10 @@ div.running {
     border-color: green;
 }
 
+td.running {
+    border: 1px solid green;
+}
+
 div.node_detail {
     width: 48%;
     float: left;

zoe_api/web/templates/status.html

@@ -209,6 +209,7 @@
     </div>
 
     <h3 class="section"><a name="service-distrib">Service distribution</a></h3>
+    <p>Services marked with a green border are essential, elastic ones have no border.</p>
     <table class="service-distrib">
     <thead>
     <tr>
@@ -222,7 +223,7 @@
         <td class="cell-host">{{ node.name }}</td>
         {% for service in services_per_node[node.name] %}
             {% if service.backend_status == "started" %}
-            <td><a href="{{ reverse_url('execution_inspect', service['execution_id']) }}">{{ service['name'] }}</a> (M: <script>format_bytes({{ node.service_stats[service['id']]['mem_limit'] }});</script> C: {{ '%0.2f'|format(node.service_stats[service['id']]['core_limit']|float) }})</td>
+            <td class="{{ 'running' if service.essential }}"><a href="{{ reverse_url('execution_inspect', service['execution_id']) }}">{{ service['name'] }}</a> (M: <script>format_bytes({{ node.service_stats[service['id']]['mem_limit'] }});</script> C: {{ '%0.2f'|format(node.service_stats[service['id']]['core_limit']|float) }})</td>
             {% endif %}
         {% endfor %}
     </tr>

zoe_api/web/templates/zapp_start.html

@@ -25,6 +25,7 @@
                         {% endif %}</li>
             <li>Suggested CPU core allocation limit: {{ service["resources"]["cores"]["min"] if service["resources"]["cores"]["min"] != None else "No limit" }}</li>
         </ul></li>
+        <li>Image: <code>{{ service["image"] }}</code></li>
     {% endfor %}
     </ul>
 

zoe_master/backends/docker/backend.py

@@ -213,7 +213,7 @@ class DockerEngineBackend(zoe_master.backends.base.BaseBackend):
             image = {
                 'id': dk_image.attrs['Id'],
                 'size': dk_image.attrs['Size'],
-                'names': dk_image.tags
+                'names': dk_image.tags  # type: list
             }
             for name in image['names']:
                 if name[-7:] == ':latest':  # add an image with the name without 'latest' to fake Docker image lookup algorithm
@@ -225,7 +225,11 @@ class DockerEngineBackend(zoe_master.backends.base.BaseBackend):
     def update_service(self, service, cores=None, memory=None):
         """Update a service reservation."""
         conf = self._get_config(service.backend_host)
-        engine = DockerClient(conf)
+        try:
+            engine = DockerClient(conf)
+        except ZoeException as e:
+            log.error(str(e))
+            return
         if service.backend_id is not None:
             info = engine.info()
             if cores is not None and cores > info['NCPU']: