FF-3150 feat: allow passing initial_configuration (#70)

* FF-3150 feat: allow passing initial_configuration

* FF-3150 feat: make configuration store track initialization

* FF-3150 feat: allow disabling the poller

* feat: re-export Configuration from eppo_client

* FF-3150 docs: update documentation for initialization options

* chore: bump version

* FF-3150 feat: add a method to update configuration of the running client

* check for None or 0

---------

Co-authored-by: Leo Romanovsky <[email protected]>

Author: rasendubi

README.md

@@ -81,8 +81,9 @@ The `init` function accepts the following optional configuration arguments.
 | ------ | ----- | ----- | ----- |
 | **`assignment_logger`**  | [AssignmentLogger](https://github.com/Eppo-exp/python-sdk/blob/ebc1a0b781769fe9d2e2be6fc81779eb8685a6c7/eppo_client/assignment_logger.py#L6-L10) | A callback that sends each assignment to your data warehouse. Required only for experiment analysis. See [example](#assignment-logger) below. | `None` |
 | **`is_graceful_mode`** | bool | When true, gracefully handles all exceptions within the assignment function and returns the default value. | `True` |
-| **`poll_interval_seconds`** | int | The interval in seconds at which the SDK polls for configuration updates. | `300` |
+| **`poll_interval_seconds`** | Optional[int] | The interval in seconds at which the SDK polls for configuration updates. If set to `None`, polling is disabled. | `300` |
 | **`poll_jitter_seconds`** | int | The jitter in seconds to add to the poll interval. | `30` |
+| **`initial_configuration`** | Optional[Configuration] | If set, the client will use this configuration until it fetches a fresh one. | `None` |
 
 ## Assignment logger
 

eppo_client/__init__.py

@@ -10,6 +10,9 @@
 from eppo_client.read_write_lock import ReadWriteLock
 from eppo_client.version import __version__
 
+# re-export for convenience
+from eppo_client.configuration import Configuration  # noqa: F401
+
 
 __client: Optional[EppoClient] = None
 __lock = ReadWriteLock()
@@ -32,6 +35,12 @@ def init(config: Config) -> EppoClient:
     http_client = HttpClient(base_url=config.base_url, sdk_params=sdk_params)
     flag_config_store: ConfigurationStore[Flag] = ConfigurationStore()
     bandit_config_store: ConfigurationStore[BanditData] = ConfigurationStore()
+
+    if config.initial_configuration:
+        flag_config_store.set_configurations(
+            config.initial_configuration._flags_configuration.flags
+        )
+
     config_requestor = ExperimentConfigurationRequestor(
         http_client=http_client,
         flag_config_store=flag_config_store,

eppo_client/client.py

@@ -11,6 +11,7 @@
     ActionContexts,
 )
 from eppo_client.models import Flag
+from eppo_client.configuration import Configuration
 from eppo_client.configuration_requestor import (
     ExperimentConfigurationRequestor,
 )
@@ -36,21 +37,29 @@ def __init__(
         config_requestor: ExperimentConfigurationRequestor,
         assignment_logger: AssignmentLogger,
         is_graceful_mode: bool = True,
-        poll_interval_seconds: int = POLL_INTERVAL_SECONDS_DEFAULT,
+        poll_interval_seconds: Optional[int] = POLL_INTERVAL_SECONDS_DEFAULT,
         poll_jitter_seconds: int = POLL_JITTER_SECONDS_DEFAULT,
     ):
         self.__config_requestor = config_requestor
         self.__assignment_logger = assignment_logger
         self.__is_graceful_mode = is_graceful_mode
-        self.__poller = Poller(
-            interval_millis=poll_interval_seconds * 1000,
-            jitter_millis=poll_jitter_seconds * 1000,
-            callback=config_requestor.fetch_and_store_configurations,
-        )
-        self.__poller.start()
+
+        if poll_interval_seconds:
+            self.__poller: Optional[Poller] = Poller(
+                interval_millis=poll_interval_seconds * 1000,
+                jitter_millis=poll_jitter_seconds * 1000,
+                callback=config_requestor.fetch_and_store_configurations,
+            )
+            self.__poller.start()
+        else:
+            self.__poller = None
+
         self.__evaluator = Evaluator(sharder=MD5Sharder())
         self.__bandit_evaluator = BanditEvaluator(sharder=MD5Sharder())
 
+    def set_configuration(self, configuration: Configuration):
+        self.__config_requestor._set_configuration(configuration)
+
     def get_string_assignment(
         self,
         flag_key: str,
@@ -434,7 +443,8 @@ def _shutdown(self):
         """Stops all background processes used by the client
         Do not use the client after calling this method.
         """
-        self.__poller.stop()
+        if self.__poller:
+            self.__poller.stop()
 
 
 def check_type_match(

eppo_client/config.py

@@ -1,7 +1,9 @@
 from pydantic import Field, ConfigDict
+from typing import Optional
 
 from eppo_client.assignment_logger import AssignmentLogger
 from eppo_client.base_model import SdkBaseModel
+from eppo_client.configuration import Configuration
 from eppo_client.validation import validate_not_blank
 from eppo_client.constants import (
     POLL_INTERVAL_SECONDS_DEFAULT,
@@ -19,8 +21,9 @@ class Config(SdkBaseModel):
     base_url: str = "https://fscdn.eppo.cloud/api"
     assignment_logger: AssignmentLogger = Field(exclude=True)
     is_graceful_mode: bool = True
-    poll_interval_seconds: int = POLL_INTERVAL_SECONDS_DEFAULT
+    poll_interval_seconds: Optional[int] = POLL_INTERVAL_SECONDS_DEFAULT
     poll_jitter_seconds: int = POLL_JITTER_SECONDS_DEFAULT
+    initial_configuration: Optional[Configuration] = None
 
     def _validate(self):
         validate_not_blank("api_key", self.api_key)

eppo_client/configuration.py

@@ -0,0 +1,11 @@
+from eppo_client.models import UfcResponse
+
+
+class Configuration:
+    """
+    Client configuration fetched from the backend that dictates how to
+    interpret feature flags.
+    """
+
+    def __init__(self, flags_configuration: str):
+        self._flags_configuration = UfcResponse.model_validate_json(flags_configuration)

eppo_client/configuration_requestor.py

@@ -1,5 +1,6 @@
 import logging
 from typing import Dict, Optional, cast
+from eppo_client.configuration import Configuration
 from eppo_client.configuration_store import ConfigurationStore
 from eppo_client.http_client import HttpClient
 from eppo_client.models import BanditData, Flag
@@ -21,7 +22,6 @@ def __init__(
         self.__http_client = http_client
         self.__flag_config_store = flag_config_store
         self.__bandit_config_store = bandit_config_store
-        self.__is_initialized = False
 
     def get_configuration(self, flag_key: str) -> Optional[Flag]:
         if self.__http_client.is_unauthorized():
@@ -70,9 +70,13 @@ def fetch_and_store_configurations(self):
             if flag_data.get("bandits", {}):
                 bandit_data = self.fetch_bandits()
                 self.store_bandits(bandit_data)
-            self.__is_initialized = True
         except Exception as e:
             logger.error("Error retrieving configurations: " + str(e))
 
     def is_initialized(self):
-        return self.__is_initialized
+        return self.__flag_config_store.is_initialized()
+
+    def _set_configuration(self, configuration: Configuration):
+        self.__flag_config_store.set_configurations(
+            configuration._flags_configuration.flags
+        )

eppo_client/configuration_store.py

@@ -7,6 +7,7 @@
 
 class ConfigurationStore(Generic[T]):
     def __init__(self):
+        self.__is_initialized = False
         self.__cache: Dict[str, T] = {}
         self.__lock = ReadWriteLock()
 
@@ -16,6 +17,7 @@ def get_configuration(self, key: str) -> Optional[T]:
 
     def set_configurations(self, configs: Dict[str, T]):
         with self.__lock.writer():
+            self.__is_initialized = True
             self.__cache = configs
 
     def get_keys(self):
@@ -25,3 +27,7 @@ def get_keys(self):
     def get_configurations(self):
         with self.__lock.reader():
             return self.__cache
+
+    def is_initialized(self) -> bool:
+        with self.__lock.reader():
+            return self.__is_initialized

eppo_client/models.py

@@ -55,6 +55,10 @@ class Flag(SdkBaseModel):
     total_shards: int = 10_000
 
 
+class UfcResponse(SdkBaseModel):
+    flags: Dict[str, Flag]
+
+
 class BanditVariation(SdkBaseModel):
     key: str
     flag_key: str

eppo_client/version.py

@@ -1,4 +1,4 @@
 # Note to developers: When ready to bump to 4.0, please change
 # the `POLL_INTERVAL_SECONDS` constant in `eppo_client/constants.py`
 # to 30 seconds to match the behavior of the other server SDKs.
-__version__ = "3.6.0"
+__version__ = "3.7.0"

test/client_no_poller_test.py

@@ -0,0 +1,13 @@
+import eppo_client
+from eppo_client.config import Config
+from eppo_client.assignment_logger import AssignmentLogger
+
+
+def test_no_poller():
+    eppo_client.init(
+        Config(
+            api_key="blah",
+            poll_interval_seconds=None,
+            assignment_logger=AssignmentLogger(),
+        )
+    )