etcd lookup: use $ANSIBLE_ETCD_URL if it exists in the env

lib/ansible/runner/lookup_plugins/etcd.py

@@ -16,6 +16,7 @@
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
 from ansible import utils
+import os
 import urllib2
 try:
     import json
@@ -24,6 +25,8 @@ except ImportError:
 
 # this can be made configurable, not should not use ansible.cfg
 ANSIBLE_ETCD_URL = 'http://127.0.0.1:4001'
+if os.getenv('ANSIBLE_ETCD_URL') is not None:
+    ANSIBLE_ETCD_URL = os.environ['ANSIBLE_ETCD_URL']
 
 class etcd():
     def __init__(self, url=ANSIBLE_ETCD_URL):