App Config - Feature Flag load/refresh (#33411)

* Splitting Out Feature Flag Refresh

* Fixing Feature Flag Refresh

* Fixing Feature Management Refresh Tests

* Fixing refresh lock

* Fixing lint

* Fixing lint

* Test error

* Update linting

* Update _azureappconfigurationprovider.py

* Fix merge issue. Added Sample

* Update feature_flag_sample.py

* Update sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_azureappconfigurationprovider.py

Co-authored-by: Ross Grambo <[email protected]>

* Update sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_azureappconfigurationprovider.py

Co-authored-by: Ross Grambo <[email protected]>

* Update sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_azureappconfigurationprovider.py

Co-authored-by: Ross Grambo <[email protected]>

* Fixing param definition. And trimming logic.

* Formatting

* Update sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_azureappconfigurationprovider.py

Co-authored-by: Ross Grambo <[email protected]>

* Update _azureappconfigurationprovider.py

---------

Co-authored-by: Ross Grambo <[email protected]>

Author: mrm9084

sdk/appconfiguration/azure-appconfiguration-provider/assets.json

@@ -2,5 +2,5 @@
   "AssetsRepo": "Azure/azure-sdk-assets",
   "AssetsRepoPrefixPath": "python",
   "TagPrefix": "python/appconfiguration/azure-appconfiguration-provider",
-  "Tag": "python/appconfiguration/azure-appconfiguration-provider_51fb3fb738"
+  "Tag": "python/appconfiguration/azure-appconfiguration-provider_29963ddf05"
 }

sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_azureappconfigurationprovider.py

@@ -100,6 +100,17 @@ def load(
     :paramtype on_refresh_error: Optional[Callable[[Exception], None]]
     :keyword on_refresh_error: Optional callback to be invoked when an error occurs while refreshing settings. If not
     specified, errors will be raised.
+    :paramtype feature_flag_enabled: bool
+    :keyword feature_flag_enabled: Optional flag to enable or disable the loading of feature flags. Default is False.
+    :paramtype feature_flag_selectors: List[SettingSelector]
+    :keyword feature_flag_selectors: Optional list of selectors to filter feature flags. By default will load all
+    feature flags without a label.
+    :paramtype feature_flag_refresh_enabled: bool
+    :keyword feature_flag_refresh_enabled: Optional flag to enable or disable the refresh of feature flags. Default is
+     False.
+    :paramtype feature_flag_trim_prefixes: List[str]
+    :keyword feature_flag_trim_prefixes: After the FEATURE_FLAG_PREFIX is trimmed, the first match in
+    feature_flag_trim_prefixes will be trimmed, if there is one.
     """
 
 
@@ -144,6 +155,17 @@ def load(
     :paramtype on_refresh_error: Optional[Callable[[Exception], None]]
     :keyword on_refresh_error: Optional callback to be invoked when an error occurs while refreshing settings. If not
     specified, errors will be raised.
+    :paramtype feature_flag_enabled: bool
+    :keyword feature_flag_enabled: Optional flag to enable or disable the loading of feature flags. Default is False.
+    :paramtype feature_flag_selectors: List[SettingSelector]
+    :keyword feature_flag_selectors: Optional list of selectors to filter feature flags. By default will load all
+    feature flags without a label.
+    :paramtype feature_flag_refresh_enabled: bool
+    :keyword feature_flag_refresh_enabled: Optional flag to enable or disable the refresh of feature flags. Default is
+     False.
+    :paramtype feature_flag_trim_prefixes: List[str]
+    :keyword feature_flag_trim_prefixes: After the FEATURE_FLAG_PREFIX is trimmed, the first match in
+    feature_flag_trim_prefixes will be trimmed, if there is one.
     """
 
 
@@ -438,12 +460,19 @@ def __init__(self, **kwargs) -> None:
             or self._keyvault_client_configs is not None
             or self._secret_resolver is not None
         )
+        self._feature_flag_enabled = kwargs.pop("feature_flag_enabled", False)
+        self._feature_flag_selectors = kwargs.pop("feature_flag_selectors", [SettingSelector(key_filter="*")])
+        self._refresh_on_feature_flags = None
+        self._feature_flag_refresh_timer: _RefreshTimer = _RefreshTimer(**kwargs)
+        self._feature_flag_refresh_enabled = kwargs.pop("feature_flag_refresh_enabled", False)
+        feature_flag_trim_prefixes = kwargs.pop("feature_flag_trim_prefixes", [])
+        self._feature_flag_trim_prefixes: List[str] = sorted(feature_flag_trim_prefixes, key=len, reverse=True)
         self._update_lock = Lock()
         self._refresh_lock = Lock()
 
     def refresh(self, **kwargs) -> None:
-        if not self._refresh_on:
-            logging.debug("Refresh called but no refresh options set.")
+        if not self._refresh_on and not self._feature_flag_refresh_enabled:
+            logging.debug("Refresh called but no refresh enabled.")
             return
         if not self._refresh_timer.needs_refresh():
             logging.debug("Refresh called but refresh interval not elapsed.")
@@ -503,7 +532,76 @@ def refresh(self, **kwargs) -> None:
             elif need_refresh and self._on_refresh_success:
                 self._on_refresh_success()
 
+    def refresh_configuration_settings(self, configuration_settings, sentinel_keys, timer, **kwargs) -> None:
+        success = False
+        need_refresh = False
+        updated_feature_flags = False
+        headers = _get_headers("Watch", uses_key_vault=self._uses_key_vault, **kwargs)
+        try:
+            for (key, label), etag in sentinel_keys.items():
+                etag, update, is_feature_flag, configuration_settings = self._check_configuration_settings(
+                    key, label, etag, headers, configuration_settings, **kwargs
+                )
+                if update and not is_feature_flag:
+                    need_refresh = True
+                elif update and is_feature_flag:
+                    updated_feature_flags = True
+
+                sentinel_keys[(key, label)] = etag
+            # Need to only update once, no matter how many sentinels are updated
+            if need_refresh:
+                configuration_settings, sentinel_keys = self._load_configuration_settings(
+                    headers=headers, sentinel_keys=sentinel_keys, **kwargs
+                )
+            success = True
+            # Even if we don't need to refresh, we should reset the timer
+            timer.reset()
+        except (ServiceRequestError, ServiceResponseError, HttpResponseError) as e:
+            # If a call back is provided, we should call it, otherwise raise the error
+            if not self._on_refresh_error:
+                raise
+            self._on_refresh_error(e)
+        finally:
+            # If we get an error we should retry sooner than the next refresh interval
+            if not success:
+                timer.backoff()
+        return configuration_settings, sentinel_keys, need_refresh or updated_feature_flags
+
+    def _check_configuration_settings(self, key, label, etag, headers, configuration_settings, **kwargs) -> None:
+        is_feature_flag = False
+        try:
+            updated_config = self._client.get_configuration_setting(
+                key=key, label=label, etag=etag, match_condition=MatchConditions.IfModified, headers=headers, **kwargs
+            )
+            is_feature_flag = not isinstance(updated_config, FeatureFlagConfigurationSetting)
+            if updated_config is not None:
+                if not is_feature_flag:
+                    logging.debug("Refresh all triggered by key: %s label %s.", key, label)
+                elif is_feature_flag:
+                    configuration_settings[self._process_key_name(updated_config)] = updated_config.value
+                return updated_config.etag, True, is_feature_flag, configuration_settings
+        except HttpResponseError as e:
+            if e.status_code == 404:
+                if etag is not None and not is_feature_flag:
+                    # If the sentinel is not found, it means the key/label was deleted, so we should refresh
+                    logging.debug("Refresh all triggered by key: %s label %s.", key, label)
+                elif etag is not None and is_feature_flag:
+                    configuration_settings[key] = None
+                return None, True, is_feature_flag, configuration_settings
+            raise e
+        return etag, False, is_feature_flag, configuration_settings
+
     def _load_all(self, **kwargs):
+        configuration_settings, sentinel_keys = self._load_configuration_settings(**kwargs)
+        feature_flags, feature_flag_sentinel_keys = self._load_feature_flags(**kwargs)
+        if self._feature_flag_enabled:
+            configuration_settings[FEATURE_MANAGEMENT_KEY] = feature_flags
+            self._refresh_on_feature_flags = feature_flag_sentinel_keys
+        with self._update_lock:
+            self._refresh_on = sentinel_keys
+            self._dict = configuration_settings
+
+    def _load_configuration_settings(self, **kwargs):
         configuration_settings = {}
         sentinel_keys = kwargs.pop("sentinel_keys", self._refresh_on)
         for select in self._selects:
@@ -514,30 +612,51 @@ def _load_all(self, **kwargs):
                 key = self._process_key_name(config)
                 value = self._process_key_value(config)
                 if isinstance(config, FeatureFlagConfigurationSetting):
-                    feature_management = configuration_settings.get(FEATURE_MANAGEMENT_KEY, {})
-                    feature_management[key] = value
-                    if FEATURE_MANAGEMENT_KEY not in configuration_settings:
-                        configuration_settings[FEATURE_MANAGEMENT_KEY] = feature_management
+                    # Feature flags are ignored when loaded by Selects, as they are selected from
+                    # `feature_flag_selectors`
+                    pass
                 else:
                     configuration_settings[key] = value
                 # Every time we run load_all, we should update the etag of our refresh sentinels
                 # so they stay up-to-date.
                 # Sentinel keys will have unprocessed key names, so we need to use the original key.
                 if (config.key, config.label) in self._refresh_on:
                     sentinel_keys[(config.key, config.label)] = config.etag
-        self._refresh_on = sentinel_keys
-        with self._update_lock:
-            self._dict = configuration_settings
+        return configuration_settings, sentinel_keys
+
+    def _load_feature_flags(self, **kwargs):
+        feature_flag_sentinel_keys = {}
+        loaded_feature_flags = {}
+        if self._feature_flag_enabled:
+            for select in self._feature_flag_selectors:
+                feature_flags = self._client.list_configuration_settings(
+                    key_filter=FEATURE_FLAG_PREFIX + select.key_filter, label_filter=select.label_filter, **kwargs
+                )
+                for feature_flag in feature_flags:
+                    key = self._process_key_name(feature_flag)
+                    loaded_feature_flags[key] = feature_flag.value
+                    if self._feature_flag_refresh_enabled:
+                        feature_flag_sentinel_keys[(feature_flag.key, feature_flag.label)] = feature_flag.etag
+        return loaded_feature_flags, feature_flag_sentinel_keys
 
     def _process_key_name(self, config):
         trimmed_key = config.key
         # Trim the key if it starts with one of the prefixes provided
+
+        # Feature Flags have there own prefix, so we need to trim that first
+        if isinstance(config, FeatureFlagConfigurationSetting):
+            if trimmed_key.startswith(FEATURE_FLAG_PREFIX):
+                trimmed_key = trimmed_key[len(FEATURE_FLAG_PREFIX) :]
+            for trim in self._feature_flag_trim_prefixes:
+                if trimmed_key.startswith(trim):
+                    trimmed_key = trimmed_key[len(trim) :]
+                    break
+            return trimmed_key
+
         for trim in self._trim_prefixes:
             if config.key.startswith(trim):
                 trimmed_key = config.key[len(trim) :]
                 break
-        if isinstance(config, FeatureFlagConfigurationSetting) and trimmed_key.startswith(FEATURE_FLAG_PREFIX):
-            return trimmed_key[len(FEATURE_FLAG_PREFIX) :]
         return trimmed_key
 
     def _process_key_value(self, config):

sdk/appconfiguration/azure-appconfiguration-provider/azure/appconfiguration/provider/_constants.py

@@ -4,7 +4,7 @@
 # license information.
 # -------------------------------------------------------------------------
 
-FEATURE_MANAGEMENT_KEY = "FeatureManagementFeatureFlags"
+FEATURE_MANAGEMENT_KEY = "FeatureManagement"
 FEATURE_FLAG_PREFIX = ".appconfig.featureflag/"
 
 EMPTY_LABEL = "\0"

sdk/appconfiguration/azure-appconfiguration-provider/samples/feature_flag_sample.py

@@ -0,0 +1,23 @@
+# ------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+# -------------------------------------------------------------------------
+
+from azure.appconfiguration.provider import load
+import os
+from sample_utilities import get_authority, get_audience, get_credential, get_client_modifications
+
+endpoint = os.environ.get("APPCONFIGURATION_ENDPOINT_STRING")
+authority = get_authority(endpoint)
+audience = get_audience(authority)
+credential = get_credential(authority)
+kwargs = get_client_modifications()
+
+# Connecting to Azure App Configuration using AAD, selects [] results in no configuration settings loading
+# By default, feature flags with no label are loaded when feature_flag_enabled is set to True
+config = load(endpoint=endpoint, credential=credential, selects=[], feature_flag_enabled=True, **kwargs)
+
+print(config["FeatureManagement"]["Alpha"])
+print(config["FeatureManagement"]["Beta"])
+print(config["FeatureManagement"]["Targeting"])

sdk/appconfiguration/azure-appconfiguration-provider/samples/refresh_sample_feature_flags.py

@@ -0,0 +1,73 @@
+# ------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+# -------------------------------------------------------------------------
+from azure.appconfiguration.provider import load, WatchKey
+from azure.appconfiguration import (
+    AzureAppConfigurationClient,
+    ConfigurationSetting,
+    FeatureFlagConfigurationSetting,
+)
+from sample_utilities import get_client_modifications
+import os
+import time
+
+kwargs = get_client_modifications()
+connection_string = os.environ.get("APPCONFIGURATION_CONNECTION_STRING")
+
+# Setting up a configuration setting with a known value
+client = AzureAppConfigurationClient.from_connection_string(connection_string)
+
+configuration_setting = ConfigurationSetting(key="message", value="Hello World!")
+feature_flag_setting = FeatureFlagConfigurationSetting("Beta", enabled=True)
+
+client.set_configuration_setting(configuration_setting=configuration_setting)
+client.set_configuration_setting(configuration_setting=feature_flag_setting)
+
+
+def my_callback_on_fail(error):
+    print("Refresh failed!")
+
+
+# Connecting to Azure App Configuration using connection string, and refreshing when the configuration setting message changes
+config = load(
+    connection_string=connection_string,
+    refresh_on=[WatchKey("message")],
+    refresh_on_feature_flags=True,
+    refresh_interval=1,
+    on_refresh_error=my_callback_on_fail,
+    feature_flag_enabled=True,
+    **kwargs,
+)
+
+print(config["message"])
+print(config["my_json"]["key"])
+print(config["FeatureManagement"]["Beta"])
+
+# Updating the configuration setting
+feature_flag_setting.enabled = False
+
+client.set_configuration_setting(configuration_setting=feature_flag_setting)
+
+# Waiting for the refresh interval to pass
+time.sleep(2)
+
+# Refreshing the configuration setting
+config.refresh()
+
+# Printing the updated value
+print(config["message"])
+print(config["my_json"]["key"])
+print(config["FeatureManagement"]["Beta"])
+
+# Waiting for the refresh interval to pass
+time.sleep(2)
+
+# Refreshing the configuration setting with no changes
+config.refresh()
+
+# Printing the updated value
+print(config["message"])
+print(config["my_json"]["key"])
+print(config["FeatureManagement"]["Beta"])

sdk/appconfiguration/azure-appconfiguration-provider/tests/asynctestcase.py

@@ -27,6 +27,7 @@ async def create_aad_client(
         secret_resolver=None,
         key_vault_options=None,
         on_refresh_success=None,
+        feature_flag_enabled=False,
     ):
         cred = self.get_credential(AzureAppConfigurationClient, is_async=True)
 
@@ -50,6 +51,7 @@ async def create_aad_client(
                 user_agent="SDK/Integration",
                 keyvault_credential=keyvault_cred,
                 on_refresh_success=on_refresh_success,
+                feature_flag_enabled=feature_flag_enabled,
             )
         if key_vault_options:
             if not key_vault_options.secret_resolver:
@@ -64,6 +66,7 @@ async def create_aad_client(
                 user_agent="SDK/Integration",
                 key_vault_options=key_vault_options,
                 on_refresh_success=on_refresh_success,
+                feature_flag_enabled=feature_flag_enabled,
             )
         return await load(
             credential=cred,
@@ -75,6 +78,7 @@ async def create_aad_client(
             user_agent="SDK/Integration",
             secret_resolver=secret_resolver,
             on_refresh_success=on_refresh_success,
+            feature_flag_enabled=feature_flag_enabled,
         )
 
     async def create_client(
@@ -88,6 +92,7 @@ async def create_client(
         secret_resolver=None,
         key_vault_options=None,
         on_refresh_success=None,
+        feature_flag_enabled=False,
     ):
         client = AzureAppConfigurationClient.from_connection_string(appconfiguration_connection_string)
         await setup_configs(client, keyvault_secret_url)
@@ -102,6 +107,7 @@ async def create_client(
                 user_agent="SDK/Integration",
                 keyvault_credential=self.get_credential(AzureAppConfigurationClient, is_async=True),
                 on_refresh_success=on_refresh_success,
+                feature_flag_enabled=feature_flag_enabled,
             )
         if key_vault_options:
             if not key_vault_options.secret_resolver:
@@ -117,6 +123,7 @@ async def create_client(
                 user_agent="SDK/Integration",
                 key_vault_options=key_vault_options,
                 on_refresh_success=on_refresh_success,
+                feature_flag_enabled=feature_flag_enabled,
             )
         return await load(
             connection_string=appconfiguration_connection_string,
@@ -127,6 +134,7 @@ async def create_client(
             user_agent="SDK/Integration",
             secret_resolver=secret_resolver,
             on_refresh_success=on_refresh_success,
+            feature_flag_enabled=feature_flag_enabled,
         )