Make GRAFANA_HEADERS environment optional

The current solution does not allow the GRAFANA_HEADERS to be optional. Pulling the if statement outside the dictionary comprehension to allow the variable to be optional.

src/grafanaSettings.py

@@ -2,7 +2,12 @@ import os
 
 GRAFANA_URL = os.getenv('GRAFANA_URL', 'http://localhost:3000')
 TOKEN = os.getenv('GRAFANA_TOKEN', 'eyJrIjoiSkQ5NkdvWllHdnVNdlVhWUV3Tm5LSGc4NG53UFdSTjQiLCJuIjoiYWRtaW4iLCJpZCI6MX0=')
-EXTRA_HEADERS = dict(h.split(':') for h in os.getenv('GRAFANA_HEADERS').split(',') if 'GRAFANA_HEADERS' in os.environ)
+
+if 'GRAFANA_HEADERS' in os.environ:
+    EXTRA_HEADERS = dict(h.split(':') for h in os.getenv('GRAFANA_HEADERS').split(','))
+else:
+    EXTRA_HEADERS = {}
+
 HTTP_GET_HEADERS = {'Authorization': 'Bearer ' + TOKEN, **EXTRA_HEADERS}
 HTTP_POST_HEADERS = {'Authorization': 'Bearer ' + TOKEN, 'Content-Type': 'application/json', **EXTRA_HEADERS}
 SEARCH_API_LIMIT = 5000