Add tag metadata to the instances.

buildman/manager/executor.py

@@ -118,7 +118,13 @@ class EC2Executor(BuilderExecutor):
     elif len(reservation.instances) != 1:
       raise ExecutorException('EC2 started wrong number of instances!')
 
-    return reservation.instances[0].id
+    launched = reservation.instances[0]
+    launched.add_tags({
+        'Name': 'Quay Ephemeral Builder',
+        'Realm': realm,
+        'Token': token,
+    })
+    return launched.id
 
   def stop_builder(self, builder_id):
     ec2_conn = self._get_conn()