Change default host for etcd connections from localhost to 127.0.0.1

On RHEL7, and with eventlet < 0.17, and if python-dns is installed, it
doesn't work for a program that uses eventlet to connect to
'localhost'.  This is because:

- RHEL7's /etc/hosts file maps 'localhost' to ::1 as well as to
  127.0.0.1.

- eventlet monkey patches DNS resolution (using python-dns, so that it
  doesn't block all eventlet threads) but the <0.17 code does this in
  a way that doesn't support IPv6 addresses.

The result is that affected systems see an error like this:

2016-03-01 12:09:49.270 10887 TRACE etcd.client MaxRetryError:
HTTPConnectionPool(host='localhost', port=4001): Max retries exceeded
with url: /v2/keys/calico/openstack/v1/neutron_election (Caused by
ProtocolError('Connection aborted.', gaierror(-9, 'Address family for
hostname not supported')))

The RHEL7 Juno repository has eventlet 0.15.2, and current Calico
depends on python-etcd 0.4.3, which in turn depends on python-dns.  So
a Calico install with Juno on RHEL7 is affected by this.
Specifically, the Neutron server hits the above error when the Calico
mechanism driver connects to etcd.

The Calico DHCP agent would also hit a similar error if we used it
with a Juno release.  Currently the Calico DHCP agent is incompatible
with Juno for other reasons; but we plan to address those reasons, so
it makes sense to fix this 'localhost' problem in the Calico DHCP
agent code too.

In both cases, the pragmatic fix is to change 'localhost' to
'127.0.0.1', so that name resolution is not needed.

Change-Id: Ia96d509f4e2a4d49419557aee3f85b8ab9f2518c
Sem-Ver: bugfix

debian/changelog

@@ -1,3 +1,9 @@
+networking-calico (1:1.1.3) trusty; urgency=low
+
+  * Change default host for etcd connections from localhost to 127.0.0.1
+
+ -- Neil Jerram <Neil.Jerram@metaswitch.com>  Wed, 02 Mar 2016 14:08:51 +0000
+
 networking-calico (1:1.1.2) trusty; urgency=low
 
   * Improve workaround for requests/urllib3 vendoring issue

debian/rules

@@ -3,7 +3,7 @@
 # Uncomment this to turn on verbose mode.
 #export DH_VERBOSE=1
 
-export PBR_VERSION=1.1.2
+export PBR_VERSION=1.1.3
 
 %:
 	dh $@  --with python2

networking_calico/agent/dhcp_agent.py

@@ -127,7 +127,7 @@ def _empty_network(self):
 
     def __init__(self, agent):
         super(CalicoEtcdWatcher, self).__init__(
-            'localhost:4001',
+            '127.0.0.1:4001',
             dir_for_host(socket.gethostname()) + "/workload"
         )
         self.agent = agent
@@ -413,7 +413,7 @@ def on_dir_delete(self, response, *args, **kwargs):
 class SubnetWatcher(EtcdWatcher):
 
     def __init__(self, endpoint_watcher):
-        super(SubnetWatcher, self).__init__('localhost:4001', SUBNET_DIR)
+        super(SubnetWatcher, self).__init__('127.0.0.1:4001', SUBNET_DIR)
         self.endpoint_watcher = endpoint_watcher
         self.register_path(
             SUBNET_DIR + "/<subnet_id>",

networking_calico/plugins/ml2/drivers/calico/t_etcd.py

@@ -54,7 +54,7 @@
 # Register Calico-specific options.
 calico_opts = [
     # etcd connection information.
-    cfg.StrOpt('etcd_host', default='localhost',
+    cfg.StrOpt('etcd_host', default='127.0.0.1',
                help="The hostname or IP of the etcd node/proxy"),
     cfg.IntOpt('etcd_port', default=4001,
                help="The port to use for the etcd node/proxy"),

rpm/networking-calico.spec

@@ -3,8 +3,8 @@
 Name:           networking-calico
 Summary:        Project Calico networking for OpenStack/Neutron
 Epoch:          1
-Version:        1.1.2
-Release:        2%{?dist}
+Version:        1.1.3
+Release:        1%{?dist}
 License:        Apache-2
 URL:            http://docs.openstack.org/developer/networking-calico/
 Source0:        networking-calico-%{version}.tar.gz
@@ -161,6 +161,9 @@ rm -rf $RPM_BUILD_ROOT
 
 
 %changelog
+* Wed Mar 02 2016 Neil Jerram <Neil.Jerram@metaswitch.com> 1:1.1.3-1
+  - Change default host for etcd connections from localhost to 127.0.0.1
+
 * Tue Mar 01 2016 Neil Jerram <Neil.Jerram@metaswitch.com> 1:1.1.2-2
   - Make networking-calico package depend on python-pbr