From c435f5c127497274aeadd97f2bbc824e85863b5d Mon Sep 17 00:00:00 2001
From: Jake Moshenko <jake.moshenko@coreos.com>
Date: Wed, 10 Jun 2015 15:44:26 -0400
Subject: [PATCH] Add a comment about why we are taking a lock when terminating
 a builder machine.

---
 buildman/manager/ephemeral.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/buildman/manager/ephemeral.py b/buildman/manager/ephemeral.py
index 9a17b38fe..5f3ebb68c 100644
--- a/buildman/manager/ephemeral.py
+++ b/buildman/manager/ephemeral.py
@@ -105,6 +105,8 @@ class EphemeralBuilderManager(BaseManager):
       if 'builder_id' in job_metadata:
         builder_id = job_metadata['builder_id']
 
+        # Before we delete the build node, we take a lock to make sure that only one manager
+        # can terminate the node.
         try:
           lock_key = self._etcd_lock_key(builder_id)
           yield From(self._etcd_client.write(lock_key, '', prevExist=False, ttl=self.setup_time()))