From 919b78248643d7c84e7f0056831adfc9810ca396 Mon Sep 17 00:00:00 2001
From: Eric K <ekcs.openstack@gmail.com>
Date: Fri, 2 Feb 2018 15:22:36 -0800
Subject: [PATCH] eventlet workaround to avoid import cycle issue

Do get_hub() before monkey_patch() to workaround issue with
import cycles in eventlet < 0.22.0;
Based on the worked-around in eventlet with patch
https://github.com/eventlet/eventlet/commit/b756447bab51046dfc6f1e0e299cc997ab343701

Also moved monkey_patch() up as far as possible to make sure all imports
get patched modules.

Closes-Bug: 1746136
Closes-Bug: 1745112

Conceptually cherry-picked from change I72c349e81dfc02136b22637c707ad4908c9f269e

Change-Id: I0ed736f30f8fd7a3ec046e5810b84b52910fa4c9
---
 congress/server/congress_server.py                  | 13 +++++++++++--
 .../notes/eventlet-cycle-103edf0cfbafd947.yaml      | 10 ++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 releasenotes/notes/eventlet-cycle-103edf0cfbafd947.yaml

diff --git a/congress/server/congress_server.py b/congress/server/congress_server.py
index ec2f1d6ed..f7a85c3ac 100644
--- a/congress/server/congress_server.py
+++ b/congress/server/congress_server.py
@@ -18,11 +18,20 @@
 from __future__ import print_function
 from __future__ import division
 from __future__ import absolute_import
+
+# NOTE(ekcs): monkey_patch ASAP to ensure all imports get patched modules
+import eventlet
+# NOTE(ekcs): get_hub() before monkey_patch() to workaround issue with
+# import cycles in eventlet < 0.22.0;
+# Based on the worked-around in eventlet with patch
+# https://github.com/eventlet/eventlet/commit/b756447bab51046dfc6f1e0e299cc997ab343701
+# For details please check https://bugs.launchpad.net/congress/+bug/1746136
+eventlet.hubs.get_hub()
+eventlet.monkey_patch()
+
 import socket
 import sys
 
-import eventlet
-eventlet.monkey_patch()
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_service import service
diff --git a/releasenotes/notes/eventlet-cycle-103edf0cfbafd947.yaml b/releasenotes/notes/eventlet-cycle-103edf0cfbafd947.yaml
new file mode 100644
index 000000000..c6e1edd27
--- /dev/null
+++ b/releasenotes/notes/eventlet-cycle-103edf0cfbafd947.yaml
@@ -0,0 +1,10 @@
+---
+prelude: >
+fixes:
+  - |
+    On Ubuntu 16.04.3, an eventlet import cycle issue
+    can prevent Congress from starting. A workaround
+    is put in place in Congress to avoid this issue.
+    For more information, see the workaround released
+    in eventlet 0.22:
+    https://github.com/eventlet/eventlet/commit/b756447bab51046dfc6f1e0e299cc997ab343701