Make current release as default

Before the patch Stackalytics dashboard by default showed the latest
configured release. With this patch the current is chosen, if it's not
available then the latest.

Change-Id: I299eee135c85bd67e611f4cb04dc868854482fc1
Closes-Bug: #1451766

stackalytics/dashboard/parameters.py

@@ -17,6 +17,7 @@ import flask
 from oslo_config import cfg
 from oslo_log import log as logging
 from six.moves.urllib import parse
+import time
 
 from stackalytics.dashboard import vault
 
@@ -72,7 +73,12 @@ def get_default(param_name):
             runtime_storage_inst = vault.get_runtime_storage()
             releases = runtime_storage_inst.get_by_key('releases')
             if releases:
-                release = releases[-1]['release_name']
+                for r in releases:
+                    if r['end_date'] > time.time():
+                        release = r['release_name']
+                        break
+                else:
+                    release = releases[-1]['release_name']
             else:
                 release = 'all'
         DEFAULTS['release'] = release.lower()