hide custom leaderboard size behind a feature flag (#128)

.env.example

@@ -41,3 +41,5 @@ REDIS_DB=0
 REDIS_USE_SSL=false
 SCORE_SUBMISSION_ROUTING_KEYS=score_submission
 PULL_SECRETS_FROM_VAULT=
+LEADERBOARD_SIZE=100
+AMPLITUDE_DEPLOYMENT_KEY=

app/adapters/feature_flags.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import logging
+
+from amplitude_experiment import Experiment
+from amplitude_experiment import User
+
+import config
+
+experiment = Experiment.initialize_local(config.AMPLITUDE_DEPLOYMENT_KEY)
+
+
+def is_feature_enabled(
+    feature_name: str,
+    *,
+    user_id: str | None = None,
+    device_id: str | None = None,
+) -> bool:
+    try:
+        if not experiment.poller.is_running:
+            experiment.start()
+
+        if device_id is None and user_id is None:
+            user_id = "1xx"
+
+        user = User(device_id=device_id, user_id=user_id)  # type: ignore[unused-ignore]
+        variant = experiment.evaluate_v2(user, {feature_name}).get(feature_name)
+        if variant is None:
+            return False
+
+        return variant.value == "on"  # type: ignore[no-any-return]
+    except Exception:
+        logging.exception(
+            "Failed to retrieve experiment",
+            extra={"feature_name": feature_name},
+        )
+        return False

app/api/leaderboards.py

@@ -8,6 +8,7 @@
 from fastapi import Query
 from fastapi import Response
 
+import app.adapters.feature_flags
 import app.state
 import app.usecases
 import config
@@ -110,6 +111,10 @@ async def get_leaderboard(
         if (
             user.privileges & Privileges.USER_PREMIUM
             and user.leaderboard_size is not None
+            and app.adapters.feature_flags.is_feature_enabled(
+                "use_custom_leaderboard_size",
+                user_id=str(user.id),
+            )
         ):
             leaderboard_size = user.leaderboard_size
         else:

config.py

@@ -72,3 +72,5 @@
 )
 
 LEADERBOARD_SIZE = config("LEADERBOARD_SIZE", cast=int, default=100)
+
+AMPLITUDE_DEPLOYMENT_KEY = config("AMPLITUDE_DEPLOYMENT_KEY")

mypy.ini

@@ -17,3 +17,6 @@ ignore_missing_imports = True
 
 [mypy-py3rijndael.*]
 ignore_missing_imports = True
+
+[mypy-amplitude_experiment.*]
+ignore_missing_imports = True

requirements.txt

@@ -1,5 +1,6 @@
 aio-pika
 aiobotocore
+amplitude-experiment
 bcrypt
 cryptography
 databases[asyncmy]