fix(gitlab) When gitlab requests fail respond with a 400 (#13691)

Don't fail and create sentry issues when GitLab instances cannot be
reached, timeout or otherwise behave poorly.

Fixes SENTRY-B2C

Author: markstory

src/sentry/integrations/gitlab/search.py

@@ -1,8 +1,10 @@
 from __future__ import absolute_import
 
+import six
 from rest_framework.response import Response
 
 from sentry.api.bases.integration import IntegrationEndpoint
+from sentry.integrations.exceptions import ApiError
 from sentry.models import Integration
 
 
@@ -37,15 +39,21 @@ def get(self, request, organization, integration_id):
             except ValueError:
                 iids = None
 
-            response = installation.search_issues(query=query, project_id=project, iids=iids)
+            try:
+                response = installation.search_issues(query=query, project_id=project, iids=iids)
+            except ApiError as e:
+                return Response({'detail': six.text_type(e)}, status=400)
 
             return Response([{
                 'label': '(#%s) %s' % (i['iid'], i['title']),
                 'value': '%s#%s' % (i['project_id'], i['iid'])
             } for i in response])
 
         elif field == 'project':
-            response = installation.search_projects(query)
+            try:
+                response = installation.search_projects(query)
+            except ApiError as e:
+                return Response({'detail': six.text_type(e)}, status=400)
             return Response([{
                 'label': project['name_with_namespace'],
                 'value': project['id'],

tests/sentry/integrations/gitlab/test_search.py

@@ -255,7 +255,7 @@ def test_search_issues_request_fails(self):
                 'project': '5',
             }
         )
-        assert resp.status_code == 503
+        assert resp.status_code == 400
 
     def test_projects_request_fails(self):
         responses.add(
@@ -269,4 +269,4 @@ def test_projects_request_fails(self):
                 'query': 'GetSentry',
             }
         )
-        assert resp.status_code == 503
+        assert resp.status_code == 400