bug-1901998: fix buginfo view to stop sending sentry errors (#6779)

When Bugzilla is in a mood, the buginfo view queries the BugInfo API and
that API throws a requests.exceptions.RetryError which the buginfo view
didn't handle and thus we end up with a Sentry error.

When this happens, the report view Bugzilla tab gets back an HTTP 500
from querying the buginfo view and kind of shrugs and doesn't show bug
details. The user isn't really impacted--they can continue their merry
day.

Bugzilla seems to be down a lot, so we get these Sentry errors we're not
going to do anything with. Thus I did a couple of things:

1. increase the backoff_factor for Bugzilla requests giving us a little
   more time for Bugzilla to find its happy place
2. change the buginfo view to handle the RetryError by returning an HTTP
   500 with an error message and _not_ sending a Sentry event

webapp/crashstats/crashstats/models.py

@@ -57,7 +57,7 @@ def get_bugs_and_related_bugs(self, signatures):
 
 
 class BugAssociation(models.Model):
-    """Specifies assocations between bug ids in Bugzilla and signatures"""
+    """Specifies associations between bug ids in Bugzilla and signatures"""
 
     bug_id = models.IntegerField(null=False, help_text="Bugzilla bug id")
     signature = models.TextField(
@@ -244,7 +244,7 @@ class ParameterTypeError(Exception):
 
 
 def _clean_path(path):
-    """Santize a URL path
+    """Sanitize a URL path
 
     :arg path: the path to sanitize
 
@@ -608,7 +608,7 @@ class ProcessedCrash(SocorroMiddleware):
     HELP_TEXT = """
     API for retrieving crash data generated by processing.
 
-    Requires protected data acess to view protected parts of the processed crash.
+    Requires protected data access to view protected parts of the processed crash.
 
     Params:
 
@@ -1027,6 +1027,9 @@ def get(self, bugs, **kwargs):
                 # 503 = Service Unavailable
                 # 504 = Gateway Time-out
                 status_forcelist=(500, 502, 503, 504),
+                # This changes backoff to (0.2, 0.4, 0.8, 1.6, 3.2) which
+                # gives Bugzilla a better chance of responding helpfully
+                backoff_factor=0.2,
             )
             response = session.get(url, headers=headers)
             if response.status_code != 200:

webapp/crashstats/crashstats/tests/test_views.py

@@ -11,6 +11,7 @@
 import requests_mock
 import pyquery
 from markus.testing import MetricsMock
+from requests.exceptions import RetryError
 
 from django.conf import settings
 from django.contrib.auth import REDIRECT_FIELD_NAME
@@ -358,6 +359,22 @@ def mocked_get(url, **options):
         cache_key = "buginfo:987"
         assert cache.get(cache_key) == struct["bugs"][0]
 
+    def test_buginfo_retry_error(self, client):
+        with requests_mock.Mocker(real_http=False) as mock_requests:
+            mock_requests.get(
+                (
+                    "http://bugzilla.example.com/rest/bug?"
+                    + "id=1901998&include_fields=summary,status,id,resolution"
+                ),
+                exc=RetryError,
+            )
+
+            url = reverse("crashstats:buginfo")
+            response = client.get(url, {"bug_ids": "1901998"})
+            assert response.status_code == 500
+            json_response = json.loads(response.content)
+            assert json_response == {"error": "Max retries exceeded with Bugzilla."}
+
 
 class Test_quick_search:
     def test_quick_search(self, client):

webapp/crashstats/crashstats/views.py

@@ -7,6 +7,7 @@
 from urllib.parse import quote
 
 import glom
+from requests.exceptions import RetryError
 
 from django import http
 from django.conf import settings
@@ -332,8 +333,10 @@ def buginfo(request, signatures=None):
     bug_ids = form.cleaned_data["bug_ids"]
 
     bzapi = models.BugzillaBugInfo()
-    result = bzapi.get(bug_ids)
-    return result
+    try:
+        return bzapi.get(bug_ids)
+    except RetryError:
+        return {"error": "Max retries exceeded with Bugzilla."}, 500
 
 
 @pass_default_context