Hide Graph Metric action of alarm when Grafana is not available

When Grafana integration is not available, click the action button of
Graph Metric will go to a non-existing Grafana page.

Added logic to hide the Graph Metric button when Grafana integration
is not avaialable. Also added unit tests for the changes.

Story: 2005906
Task: 34165

Change-Id: I617a0c609450bf015ddf6e98fd672723a2660071

monitoring/alarms/tables.py

@@ -15,6 +15,7 @@
 
 import json
 
+from django.conf import settings
 from django import template
 from django.urls import reverse
 from django.urls import reverse_lazy
@@ -25,7 +26,6 @@ from horizon import tables
 
 from monitoring.alarms import constants
 from monitoring import api
-from monitoring.config import local_settings
 from monitoring.overview import constants as ov_constants
 
 
@@ -159,7 +159,7 @@ class GraphMetric(tables.LinkAction):
         self.attrs['target'] = '_blank'
         try:
             region = self.table.request.user.services_region
-            grafana_url = getattr(local_settings, 'GRAFANA_URL').get(region, '')
+            grafana_url = getattr(settings, 'GRAFANA_URL').get(region, '')
             url = grafana_url + \
                 '/dashboard/script/drilldown.js'
             metric = datum['metrics'][0]['name']
@@ -179,7 +179,8 @@ class GraphMetric(tables.LinkAction):
         return url + query
 
     def allowed(self, request, datum=None):
-        return datum['metrics']
+        return (getattr(settings, 'GRAFANA_URL', None) is not None and
+                datum['metrics'])
 
 
 class ShowAlarmDefinition(tables.LinkAction):

monitoring/test/test_alarm_tables.py

@@ -15,6 +15,7 @@
 from __future__ import absolute_import
 
 from django.test import TestCase
+from django.test.utils import override_settings
 from mock import Mock
 
 import monitoring.alarms.tables
@@ -46,3 +47,18 @@ class GraphMetricLinkActionTests(TestCase):
             r'&threshold=[{"name": "metric1"}, {"name": "metric \u2461"}]'
             r'&api=http://foo/api/'
         )
+
+    def test_allowed_grafana_links(self):
+        allowed = self.get_allowed()
+        self.assertEqual(allowed, False)
+
+    @override_settings(GRAFANA_URL={'CustomRegion': '/grafana'})
+    def test_allowed_grafana_links_nonempty(self):
+        allowed = self.get_allowed()
+        self.assertEqual(allowed, 'metrics')
+
+    def get_allowed(self):
+        table_mock = Mock()
+        table_mock.request.build_absolute_uri.return_value = u"http://foo/api/"
+        link_action = monitoring.alarms.tables.GraphMetric(table=table_mock)
+        return link_action.allowed(table_mock.request, {'metrics': 'metrics'})