[WIP] - 422 elb rotate (#493)

* Initial work on certificate rotation.

* Adding ability to get additional certificate info.

* - Adding endpoint rotation.
- Removes the g requirement from all services to enable easier testing.

lemur/endpoints/service.py

@@ -8,6 +8,8 @@
 .. moduleauthor:: Kevin Glisson <kglisson@netflix.com>
 
 """
+from flask import current_app
+
 from lemur import database
 from lemur.extensions import metrics
 from lemur.endpoints.models import Endpoint, Policy, Cipher
@@ -96,6 +98,17 @@ def update(endpoint_id, **kwargs):
     return endpoint
 
 
+def rotate_certificate(endpoint, new_cert):
+    """Rotates a certificate on a given endpoint."""
+    try:
+        endpoint.source.plugin.update_endpoint(endpoint, new_cert)
+        endpoint.certificate = new_cert
+    except Exception as e:
+        metrics.send('rotate_failure', 'counter', 1, tags={'endpoint': endpoint.name})
+        current_app.logger.exception(e)
+        raise e
+
+
 def render(args):
     """
     Helper that helps us render the REST Api responses.