fix(feature-flags): Add more options to make using library easier (#70)

Author: neilkakkar

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 2.0.1 - 2022-08-04
+
+- Make poll_interval configurable
+- Add `send_feature_flag_events` parameter to feature flag calls, which determine whether the `$feature_flag_called` event should be sent or not.
+- Add `only_evaluate_locally` parameter to feature flag calls, which determines whether the feature flag should only be evaluated locally or not.
+
 ## 2.0.0 - 2022-08-02
 
 Breaking changes:

example.py

@@ -5,7 +5,7 @@
 
 import posthog
 
-# posthog.debug = True
+posthog.debug = True
 
 # You can find this key on the /setup page in PostHog
 posthog.project_api_key = ""
@@ -14,15 +14,14 @@
 # Where you host PostHog, with no trailing /.
 # You can remove this line if you're using posthog.com
 posthog.host = "http://localhost:8000"
+posthog.poll_interval = 10
+
 
 # Capture an event
 posthog.capture("distinct_id", "event", {"property1": "value", "property2": "value"}, send_feature_flags=True)
 
 print(posthog.feature_enabled("beta-feature", "distinct_id"))
-print(posthog.feature_enabled("beta-feature", "distinct_id", groups={"company": "id:5"}))
-
-print("sleeping")
-# time.sleep(5)
+print(posthog.feature_enabled("beta-feature-groups", "distinct_id", groups={"company": "id:5"}))
 
 print(posthog.feature_enabled("beta-feature", "distinct_id"))
 
@@ -44,7 +43,6 @@
 # properties set only once to the person
 posthog.set_once("new_distinct_id", {"self_serve_signup": True})
 
-# time.sleep(3)
 
 posthog.set_once(
     "new_distinct_id", {"self_serve_signup": False}
@@ -53,7 +51,6 @@
 posthog.set("new_distinct_id", {"current_browser": "Chrome"})
 posthog.set("new_distinct_id", {"current_browser": "Firefox"})
 
-# posthog.shutdown()
 
 # #############################################################################
 # Make sure you have a personal API key for the examples below
@@ -63,4 +60,23 @@
 # If flag has City=Sydney, this call doesn't go to `/decide`
 print(posthog.feature_enabled("test-flag", "distinct_id_random_22", person_properties={"$geoip_city_name": "Sydney"}))
 
+print(
+    posthog.feature_enabled(
+        "test-flag",
+        "distinct_id_random_22",
+        person_properties={"$geoip_city_name": "Sydney"},
+        only_evaluate_locally=True,
+    )
+)
+
+
 print(posthog.get_all_flags("distinct_id_random_22"))
+print(posthog.get_all_flags("distinct_id_random_22", only_evaluate_locally=True))
+print(
+    posthog.get_all_flags(
+        "distinct_id_random_22", person_properties={"$geoip_city_name": "Sydney"}, only_evaluate_locally=True
+    )
+)
+
+
+posthog.shutdown()

posthog/__init__.py

@@ -15,6 +15,7 @@
 disabled = False  # type: bool
 personal_api_key = None  # type: str
 project_api_key = None  # type: str
+poll_interval = 30  # type: int
 
 default_client = None
 
@@ -238,6 +239,8 @@ def feature_enabled(
     groups={},  # type: dict
     person_properties={},  # type: dict
     group_properties={},  # type: dict
+    only_evaluate_locally=False,  # type: bool
+    send_feature_flag_events=True,  # type: bool
 ):
     # type: (...) -> bool
     """
@@ -261,6 +264,8 @@ def feature_enabled(
         groups=groups,
         person_properties=person_properties,
         group_properties=group_properties,
+        only_evaluate_locally=only_evaluate_locally,
+        send_feature_flag_events=send_feature_flag_events,
     )
 
 
@@ -271,6 +276,8 @@ def get_feature_flag(
     groups={},  # type: dict
     person_properties={},  # type: dict
     group_properties={},  # type: dict
+    only_evaluate_locally=False,  # type: bool
+    send_feature_flag_events=True,  # type: bool
 ):
     """
     Get feature flag variant for users. Used with experiments.
@@ -302,6 +309,8 @@ def get_feature_flag(
         groups=groups,
         person_properties=person_properties,
         group_properties=group_properties,
+        only_evaluate_locally=only_evaluate_locally,
+        send_feature_flag_events=send_feature_flag_events,
     )
 
 
@@ -310,6 +319,7 @@ def get_all_flags(
     groups={},  # type: dict
     person_properties={},  # type: dict
     group_properties={},  # type: dict
+    only_evaluate_locally=False,  # type: bool
 ):
     """
     Get all flags for a given user.
@@ -326,6 +336,7 @@ def get_all_flags(
         groups=groups,
         person_properties=person_properties,
         group_properties=group_properties,
+        only_evaluate_locally=only_evaluate_locally,
     )
 
 
@@ -370,6 +381,7 @@ def _proxy(method, *args, **kwargs):
             sync_mode=sync_mode,
             personal_api_key=personal_api_key,
             project_api_key=project_api_key,
+            poll_interval=poll_interval,
         )
 
     fn = getattr(default_client, method)

posthog/client.py

@@ -1,10 +1,8 @@
 import atexit
 import logging
 import numbers
-from collections import defaultdict
 from datetime import datetime, timedelta
-from tokenize import group
-from uuid import UUID, uuid4
+from uuid import UUID
 
 from dateutil.tz import tzutc
 from six import string_types
@@ -25,6 +23,10 @@
 ID_TYPES = (numbers.Number, string_types, UUID)
 MAX_DICT_SIZE = 50_000
 
+# Ensures that debug level messages are logged when debug mode is on.
+# Otherwise, defaults to WARNING level. See https://docs.python.org/3/howto/logging.html#what-happens-if-no-configuration-is-provided
+logging.basicConfig()
+
 
 class Client(object):
     """Create a new PostHog client."""
@@ -73,13 +75,10 @@ def __init__(
 
         # personal_api_key: This should be a generated Personal API Key, private
         self.personal_api_key = personal_api_key
-
         if debug:
-            # Ensures that debug level messages are logged when debug mode is on.
-            # Otherwise, defaults to WARNING level. See https://docs.python.org/3/howto/logging.html#what-happens-if-no-configuration-is-provided
-            logging.basicConfig(level=logging.DEBUG)
+            self.log.setLevel(logging.DEBUG)
         else:
-            logging.basicConfig(level=logging.WARNING)
+            self.log.setLevel(logging.WARNING)
 
         if sync_mode:
             self.consumers = None
@@ -375,7 +374,7 @@ def _load_feature_flags(self):
                     "More information: https://posthog.com/docs/api/overview",
                 )
             else:
-                raise APIError(status=e.status, message=e.message)
+                self.log.error(f"[FEATURE FLAGS] Error loading feature flags: {e}")
         except Exception as e:
             self.log.warning(
                 "[FEATURE FLAGS] Fetching feature flags failed with following error. We will retry in %s seconds."
@@ -429,7 +428,18 @@ def _compute_flag_locally(self, feature_flag, distinct_id, *, groups={}, person_
         else:
             return match_feature_flag_properties(feature_flag, distinct_id, person_properties)
 
-    def feature_enabled(self, key, distinct_id, default=False, *, groups={}, person_properties={}, group_properties={}):
+    def feature_enabled(
+        self,
+        key,
+        distinct_id,
+        default=False,
+        *,
+        groups={},
+        person_properties={},
+        group_properties={},
+        only_evaluate_locally=False,
+        send_feature_flag_events=True,
+    ):
         return bool(
             self.get_feature_flag(
                 key,
@@ -438,11 +448,22 @@ def feature_enabled(self, key, distinct_id, default=False, *, groups={}, person_
                 groups=groups,
                 person_properties=person_properties,
                 group_properties=group_properties,
+                only_evaluate_locally=only_evaluate_locally,
+                send_feature_flag_events=send_feature_flag_events,
             )
         )
 
     def get_feature_flag(
-        self, key, distinct_id, default=False, *, groups={}, person_properties={}, group_properties={}
+        self,
+        key,
+        distinct_id,
+        default=False,
+        *,
+        groups={},
+        person_properties={},
+        group_properties={},
+        only_evaluate_locally=False,
+        send_feature_flag_events=True,
     ):
         require("key", key, string_types)
         require("distinct_id", distinct_id, ID_TYPES)
@@ -472,7 +493,8 @@ def get_feature_flag(
                         self.log.exception(f"[FEATURE FLAGS] Error while computing variant locally: {e}")
                         continue
 
-        if response is None:
+        flag_was_locally_evaluated = response is not None
+        if not flag_was_locally_evaluated and not only_evaluate_locally:
             try:
                 feature_flags = self.get_feature_variants(
                     distinct_id, groups=groups, person_properties=person_properties, group_properties=group_properties
@@ -483,14 +505,27 @@ def get_feature_flag(
                 self.log.exception(f"[FEATURE FLAGS] Unable to get flag remotely: {e}")
                 response = default
 
-        if key not in self.distinct_ids_feature_flags_reported[distinct_id]:
+        feature_flag_reported_key = f"{key}_{str(response)}"
+        if (
+            feature_flag_reported_key not in self.distinct_ids_feature_flags_reported[distinct_id]
+            and send_feature_flag_events
+        ):
             self.capture(
-                distinct_id, "$feature_flag_called", {"$feature_flag": key, "$feature_flag_response": response}
+                distinct_id,
+                "$feature_flag_called",
+                {
+                    "$feature_flag": key,
+                    "$feature_flag_response": response,
+                    "locally_evaluated": flag_was_locally_evaluated,
+                },
+                groups=groups,
             )
-            self.distinct_ids_feature_flags_reported[distinct_id].add(key)
+            self.distinct_ids_feature_flags_reported[distinct_id].add(feature_flag_reported_key)
         return response
 
-    def get_all_flags(self, distinct_id, *, groups={}, person_properties={}, group_properties={}):
+    def get_all_flags(
+        self, distinct_id, *, groups={}, person_properties={}, group_properties={}, only_evaluate_locally=False
+    ):
         require("distinct_id", distinct_id, ID_TYPES)
         require("groups", groups, dict)
 
@@ -520,7 +555,7 @@ def get_all_flags(self, distinct_id, *, groups={}, person_properties={}, group_p
         else:
             fallback_to_decide = True
 
-        if fallback_to_decide:
+        if fallback_to_decide and not only_evaluate_locally:
             try:
                 feature_flags = self.get_feature_variants(
                     distinct_id, groups=groups, person_properties=person_properties, group_properties=group_properties

posthog/request.py

@@ -50,19 +50,14 @@ def _process_response(
     res: requests.Response, success_message: str, *, return_json: bool = True
 ) -> Union[requests.Response, Any]:
     log = logging.getLogger("posthog")
-    if not res:
-        raise APIError(
-            "N/A",
-            "Error when fetching PostHog API, please make sure you are using your public project token/key and not a private API key.",
-        )
     if res.status_code == 200:
         log.debug(success_message)
         return res.json() if return_json else res
     try:
         payload = res.json()
         log.debug("received response: %s", payload)
         raise APIError(res.status_code, payload["detail"])
-    except ValueError:
+    except (KeyError, ValueError):
         raise APIError(res.status_code, res.text)