Handle the case where we cannot write the tags on the build nodes

buildman/manager/executor.py

@@ -143,12 +143,18 @@ class EC2Executor(BuilderExecutor):
       raise ExecutorException('EC2 started wrong number of instances!')
 
     launched = AsyncWrapper(reservation.instances[0])
-    yield From(launched.add_tags({
-        'Name': 'Quay Ephemeral Builder',
-        'Realm': realm,
-        'Token': token,
-        'BuildUUID': build_uuid,
-    }))
+
+    for i in range(0, 2):
+      try:
+        yield From(launched.add_tags({
+            'Name': 'Quay Ephemeral Builder',
+            'Realm': realm,
+            'Token': token,
+            'BuildUUID': build_uuid,
+        }))
+      except boto.exception.EC2ResponseError:
+        logger.exception('Failed to write EC2 tags (attempt #%s)', i)
+
     raise Return(launched.id)
 
   @coroutine