Add jsonData to prometheus datasource

Change-Id: I7fec57a5f347da4ea0895b8dce167ab903af9946
Closes-Bug: PROD-25437
diff --git a/_states/grafana3_datasource.py b/_states/grafana3_datasource.py
index 5efa8ba..e6937fc 100644
--- a/_states/grafana3_datasource.py
+++ b/_states/grafana3_datasource.py
@@ -262,6 +262,15 @@
         'typeLogoUrl': type_logo_url,
         'withCredentials': with_credentials,
     }
+
+    if data['type'] == 'prometheus':
+        data.update({
+            'jsonData': {
+                'httpMethod': 'GET',
+                'keepCookies': []
+            }
+        })
+
     if data['type'] == 'gnocchixyz-gnocchi-datasource':
         json_data = {}
         for special in ['mode', 'domain', 'project', 'user', 'password']: