Bump version to 2.0.0 and add breaking changes changelog (#69)

Author: neilkakkar

CHANGELOG.md

@@ -1,3 +1,18 @@
+## 2.0.0 - 2022-08-02
+
+Breaking changes:
+
+1. The minimum version requirement for PostHog servers is now 1.38. If you're using PostHog Cloud, you satisfy this requirement automatically.
+2. Feature flag defaults apply only when there's an error fetching feature flag results. Earlier, if the default was set to `True`, even if a flag resolved to `False`, the default would override this.
+3. Feature flag remote evaluation doesn't require a personal API key.
+
+New Changes:
+
+1. You can now evaluate feature flags locally (i.e. without sending a request to your PostHog servers) by setting a personal API key, and passing in groups and person properties to `is_feature_enabled` and `get_feature_flag` calls.
+2. Introduces a `get_all_flags` method that returns all feature flags. This is useful for when you want to seed your frontend with some initial flags, given a user ID.
+
+
+
 ## 1.4.9 - 2022-06-13
 - Support for sending feature flags with capture calls
 

example.py

@@ -5,6 +5,8 @@
 
 import posthog
 
+# posthog.debug = True
+
 # You can find this key on the /setup page in PostHog
 posthog.project_api_key = ""
 posthog.personal_api_key = ""
@@ -20,7 +22,7 @@
 print(posthog.feature_enabled("beta-feature", "distinct_id", groups={"company": "id:5"}))
 
 print("sleeping")
-time.sleep(5)
+# time.sleep(5)
 
 print(posthog.feature_enabled("beta-feature", "distinct_id"))
 
@@ -42,7 +44,7 @@
 # properties set only once to the person
 posthog.set_once("new_distinct_id", {"self_serve_signup": True})
 
-time.sleep(3)
+# time.sleep(3)
 
 posthog.set_once(
     "new_distinct_id", {"self_serve_signup": False}

posthog/client.py

@@ -23,7 +23,7 @@
 
 
 ID_TYPES = (numbers.Number, string_types, UUID)
-MAX_DICT_SIZE = 100_000
+MAX_DICT_SIZE = 50_000
 
 
 class Client(object):
@@ -75,7 +75,11 @@ def __init__(
         self.personal_api_key = personal_api_key
 
         if debug:
-            self.log.setLevel(logging.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)
+        else:
+            logging.basicConfig(level=logging.WARNING)
 
         if sync_mode:
             self.consumers = None
@@ -359,8 +363,8 @@ def _load_feature_flags(self):
             response = get(
                 self.personal_api_key, f"/api/feature_flag/local_evaluation/?token={self.api_key}", self.host
             )
-            self.feature_flags = [flag for flag in response["flags"] if flag["active"]]
-            self.group_type_mapping = response["group_type_mapping"]
+            self.feature_flags = response["flags"] or []
+            self.group_type_mapping = response["group_type_mapping"] or {}
 
         except APIError as e:
             if e.status == 401:
@@ -397,6 +401,9 @@ def _compute_flag_locally(self, feature_flag, distinct_id, *, groups={}, person_
         if feature_flag.get("ensure_experience_continuity", False):
             raise InconclusiveMatchError("Flag has experience continuity enabled")
 
+        if not feature_flag.get("active"):
+            return False
+
         flag_filters = feature_flag.get("filters") or {}
         aggregation_group_type_index = flag_filters.get("aggregation_group_type_index")
         if aggregation_group_type_index is not None:
@@ -457,11 +464,12 @@ def get_feature_flag(
                             person_properties=person_properties,
                             group_properties=group_properties,
                         )
+                        self.log.debug(f"Successfully computed flag locally: {key} -> {response}")
                     except InconclusiveMatchError as e:
-                        # No need to log this, since it's just telling us to fall back to `/decide`
+                        self.log.debug(f"Failed to compute flag {key} locally: {e}")
                         continue
                     except Exception as e:
-                        self.log.exception(f"[FEATURE FLAGS] Error while computing variant: {e}")
+                        self.log.exception(f"[FEATURE FLAGS] Error while computing variant locally: {e}")
                         continue
 
         if response is None:
@@ -470,8 +478,9 @@ def get_feature_flag(
                     distinct_id, groups=groups, person_properties=person_properties, group_properties=group_properties
                 )
                 response = feature_flags.get(key)
+                self.log.debug(f"Successfully computed flag remotely: #{key} -> #{response}")
             except Exception as e:
-                self.log.exception(f"[FEATURE FLAGS] Unable to get feature variants: {e}")
+                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]:

posthog/feature_flags.py

@@ -21,11 +21,9 @@ def _hash(key, distinct_id, salt=""):
 
 
 def get_matching_variant(flag, distinct_id):
+    hash_value = _hash(flag["key"], distinct_id, salt="variant")
     for variant in variant_lookup_table(flag):
-        if (
-            _hash(flag["key"], distinct_id, salt="variant") >= variant["value_min"]
-            and _hash(flag["key"], distinct_id, salt="variant") < variant["value_max"]
-        ):
+        if hash_value >= variant["value_min"] and hash_value < variant["value_max"]:
             return variant["key"]
     return None