Add error handling and timeouts

Author: timgl

posthog/client.py

@@ -240,6 +240,9 @@ def _load_feature_flags(self):
                     'To use feature flags, please set a personal_api_key ' \
                     'More information: https://posthog.com/docs/api/overview'
                 )
+        except Exception as e:
+            self.log.warning('[FEATURE FLAGS] Fetching feature flags failed with following error. We will retry in %s seconds.' % self.poll_interval)
+            self.log.warning(e)
 
         self._last_feature_flag_poll = datetime.utcnow().replace(tzinfo=tzutc())
 
@@ -251,20 +254,32 @@ def load_feature_flags(self):
     def feature_enabled(self, key, distinct_id, default=False):
         require('key', key, string_types)
         require('distinct_id', distinct_id, ID_TYPES)
+        error = False
 
         if not self.feature_flags:
             self.load_feature_flags()
 
-        try:
-            feature_flag = [flag for flag in self.feature_flags if flag['key'] == key][0]
-        except IndexError:
-            return default
-
-        if feature_flag.get('is_simple_flag'):
-            response = _hash(key, distinct_id) <= (feature_flag['rollout_percentage'] / 100)
+        # If loading in previous line failed
+        if not self.feature_flags:
+            response = default
+            error = True
         else:
-            request = get(self.api_key, '/decide/', self.host)
-            response = key in request['featureFlags']
+            try:
+                feature_flag = [flag for flag in self.feature_flags if flag['key'] == key][0]
+            except IndexError:
+                return default
+
+            if feature_flag.get('is_simple_flag'):
+                response = _hash(key, distinct_id) <= (feature_flag['rollout_percentage'] / 100)
+            else:
+                try:
+                    request = get(self.api_key, '/decide/', self.host, timeout=1)
+                    response = key in request['featureFlags']
+                except Exception as e:
+                    response = default
+                    self.log.warning('[FEATURE FLAGS] Unable to get data for flag %s, because of the following error:' % key)
+                    self.log.warning(e)
+                    error = True
 
         self.capture(distinct_id, '$feature_flag_called', {'$feature_flag': key, '$feature_flag_response': response})
         return response

posthog/request.py

@@ -51,7 +51,7 @@ def post(api_key, host=None, gzip=False, timeout=15, **kwargs):
     except ValueError:
         raise APIError(res.status_code, res.text)
 
-def get(api_key, url, host=None):
+def get(api_key, url, host=None, timeout=None):
     log = logging.getLogger('posthog')
     url = remove_trailing_slash(host or DEFAULT_HOST) + url
     response = requests.get(
@@ -60,6 +60,7 @@ def get(api_key, url, host=None):
             'Authorization': 'Bearer %s' % api_key,
             'User-Agent': USER_AGENT
         },
+        timeout=timeout
     )
     if response.status_code == 200:
         return response.json()

posthog/test/client.py

@@ -280,4 +280,26 @@ def test_feature_enabled_doesnt_exist(self, patch_get):
         client.feature_flags = []
 
         self.assertFalse(client.feature_enabled('doesnt-exist', 'distinct_id'))
-        self.assertTrue(client.feature_enabled('doesnt-exist', 'distinct_id', True))
+        self.assertTrue(client.feature_enabled('doesnt-exist', 'distinct_id', True))
+
+    @mock.patch('posthog.client.Poller')
+    @mock.patch('posthog.client.get')
+    def test_load_feature_flags_error(self, patch_get, patch_poll):
+        def raise_effect():
+            raise Exception('http exception')
+        patch_get.return_value.raiseError.side_effect = raise_effect
+        client = Client(TEST_API_KEY, personal_api_key='test')
+        client.feature_flags = []
+
+        self.assertFalse(client.feature_enabled('doesnt-exist', 'distinct_id'))
+
+    @mock.patch('posthog.client.Poller')
+    @mock.patch('posthog.client.get')
+    def test_call_identify_fails(self, patch_get, patch_poll):
+        def raise_effect():
+            raise Exception('http exception')
+        patch_get.return_value.raiseError.side_effect = raise_effect
+        client = Client(TEST_API_KEY, personal_api_key='test')
+        client.feature_flags = [{'key': 'example', 'is_simple_flag': False}]
+
+        self.assertFalse(client.feature_enabled('example', 'distinct_id'))