App Configuration - Feature flag refresh (#33693)

* Updating feature flag usage

* For some reason this isn't popped in async

* Updadating Tests

* Update CHANGELOG.md

* Formatting

* Fixing Refresh, Sync

* Updating Schema 2.0.0

* Update test_async_provider.py

* fixed refresh and merge

* fixing mypy

* fixing pylint issues

* Updated from review comments

* Update README.md

* Update README.md

* Fixed pylint issue

* Update assets.json

* formatting

* pylint and test fix

* Updating Min SDK version to bug in 1.4.0 with feature flags

* Update setup.py

* Updating so configs and feature flags don't refresh each other

* Added missing _ and tests

* Update assets.json

* Fixing MyPy issue

Author: mrm9084

sdk/appconfiguration/azure-appconfiguration-provider/CHANGELOG.md

@@ -4,6 +4,10 @@
 
 ### Features Added
 
+* Enable loading of feature flags with `feature_flag_enabled`
+* Select Feature Flags to load with `feature_flag_selectors`
+* Enable/Disable Feature Flag Refresh with `feature_flag_refresh_enabled`
+
 ### Breaking Changes
 
 ### Bugs Fixed

sdk/appconfiguration/azure-appconfiguration-provider/README.md

@@ -168,6 +168,33 @@ key_vault_options = AzureAppConfigurationKeyVaultOptions(
 config = load(endpoint=endpoint, credential=DefaultAzureCredential(), key_vault_options=key_vault_options)
 ```
 
+## Loading Feature Flags
+
+Feature Flags can be loaded from config stores using the provider. Feature flags are loaded as a dictionary of key/value pairs stored in the provider under the `FeatureManagement`, then `FeatureFlags`.
+
+```python
+config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True)
+alpha = config["FeatureManagement"]["FeatureFlags"]["Alpha"]
+print(alpha["enabled"])
+```
+
+By default all feature flags with no label are loaded. If you want to load feature flags with a specific label you can use `SettingSelector` to filter the feature flags.
+
+```python
+from azure.appconfiguration.provider import load, SettingSelector
+
+config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True, feature_flag_selectors=[SettingSelector(key_filter="*", label_filter="dev")])
+alpha = config["FeatureManagement"]["FeatureFlags"]["Alpha"]
+print(alpha["enabled"])
+```
+
+To enable refresh for feature flags you need to enable refresh. This will allow the provider to refresh feature flags the same way it refreshes configurations. Unlike configurations, all loaded feature flags are monitored for changes and will cause a refresh. Refresh of configuration settings and feature flags are independent of each other. Both are trigged by the `refresh` method, but a feature flag changing will not cause a refresh of configurations and vice versa. Also, if refresh for configuration settings is not enabled, feature flags can still be enabled for refresh.
+
+```python
+config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True, feature_flag_refresh_enabled=True)
+config.refresh()
+```
+
 ## Key concepts
 
 ## Troubleshooting

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_8a49e8ba1e"
 }

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

@@ -32,13 +32,15 @@
     AzureAppConfigurationClient,
     FeatureFlagConfigurationSetting,
     SecretReferenceConfigurationSetting,
+    ConfigurationSetting,
 )
 from azure.core import MatchConditions
 from azure.core.exceptions import HttpResponseError, ServiceRequestError, ServiceResponseError
 from azure.keyvault.secrets import SecretClient, KeyVaultSecretIdentifier
 from ._models import AzureAppConfigurationKeyVaultOptions, SettingSelector
 from ._constants import (
     FEATURE_MANAGEMENT_KEY,
+    FEATURE_FLAG_KEY,
     FEATURE_FLAG_PREFIX,
     REQUEST_TRACING_DISABLED_ENVIRONMENT_VARIABLE,
     ServiceFabricEnvironmentVariable,
@@ -107,6 +109,14 @@ 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.
     """
 
 
@@ -154,6 +164,14 @@ 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.
     """
 
 
@@ -201,6 +219,7 @@ def load(*args, **kwargs) -> "AzureAppConfigurationProvider":
     provider = _buildprovider(
         connection_string, endpoint, credential, uses_key_vault="UsesKeyVault" in headers, **kwargs
     )
+
     try:
         provider._load_all(headers=headers)
     except Exception as e:
@@ -221,6 +240,7 @@ def load(*args, **kwargs) -> "AzureAppConfigurationProvider":
                         key,
                         label,
                     )
+                    provider._refresh_on[(key, label)] = None  # type: ignore
                 else:
                     _delay_failure(start_time)
                     raise e
@@ -453,12 +473,17 @@ 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: Mapping[Tuple[str, str], Optional[str]] = {}
+        self._feature_flag_refresh_timer: _RefreshTimer = _RefreshTimer(**kwargs)
+        self._feature_flag_refresh_enabled = kwargs.pop("feature_flag_refresh_enabled", False)
         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.")
@@ -469,39 +494,10 @@ def refresh(self, **kwargs) -> None:
         success = False
         need_refresh = False
         try:
-            updated_sentinel_keys = dict(self._refresh_on)
-            headers = _get_headers("Watch", uses_key_vault=self._uses_key_vault, **kwargs)
-            for (key, label), etag in updated_sentinel_keys.items():
-                try:
-                    updated_sentinel = self._client.get_configuration_setting(  # type:ignore
-                        key=key,
-                        label=label,
-                        etag=etag,
-                        match_condition=MatchConditions.IfModified,
-                        headers=headers,
-                        **kwargs
-                    )
-                    if updated_sentinel is not None:
-                        logging.debug(
-                            "Refresh all triggered by key: %s label %s.",
-                            key,
-                            label,
-                        )
-                        need_refresh = True
-
-                        updated_sentinel_keys[(key, label)] = updated_sentinel.etag
-                except HttpResponseError as e:
-                    if e.status_code == 404:
-                        if etag is not None:
-                            # 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)
-                            need_refresh = True
-                            updated_sentinel_keys[(key, label)] = None
-                    else:
-                        raise e
-            # Need to only update once, no matter how many sentinels are updated
-            if need_refresh:
-                self._load_all(headers=headers, sentinel_keys=updated_sentinel_keys, **kwargs)
+            if self._refresh_on:
+                need_refresh = self._refresh_configuration_settings(**kwargs)
+            if self._feature_flag_refresh_enabled:
+                need_refresh = self._refresh_feature_flags(**kwargs) or need_refresh
             # Even if we don't need to refresh, we should reset the timer
             self._refresh_timer.reset()
             success = True
@@ -518,31 +514,132 @@ def refresh(self, **kwargs) -> None:
             elif need_refresh and self._on_refresh_success:
                 self._on_refresh_success()
 
+    def _refresh_configuration_settings(self, **kwargs) -> bool:
+        need_refresh = False
+        updated_sentinel_keys = dict(self._refresh_on)
+        headers = _get_headers("Watch", uses_key_vault=self._uses_key_vault, **kwargs)
+        for (key, label), etag in updated_sentinel_keys.items():
+            changed, updated_sentinel = self._check_configuration_setting(
+                key=key, label=label, etag=etag, headers=headers, **kwargs
+            )
+            if changed:
+                need_refresh = True
+            if updated_sentinel is not None:
+                updated_sentinel_keys[(key, label)] = updated_sentinel.etag
+        # Need to only update once, no matter how many sentinels are updated
+        if need_refresh:
+            configuration_settings, sentinel_keys = self._load_configuration_settings(**kwargs)
+            if self._feature_flag_enabled:
+                configuration_settings[FEATURE_MANAGEMENT_KEY] = self._dict[FEATURE_MANAGEMENT_KEY]
+            with self._update_lock:
+                self._refresh_on = sentinel_keys
+                self._dict = configuration_settings
+        return need_refresh
+
+    def _refresh_feature_flags(self, **kwargs) -> bool:
+        feature_flag_sentinel_keys = dict(self._refresh_on_feature_flags)
+        headers = _get_headers("Watch", uses_key_vault=self._uses_key_vault, **kwargs)
+        for (key, label), etag in feature_flag_sentinel_keys.items():
+            changed = self._check_configuration_setting(key=key, label=label, etag=etag, headers=headers, **kwargs)
+            if changed:
+                feature_flags, feature_flag_sentinel_keys = self._load_feature_flags(**kwargs)
+                with self._update_lock:
+                    updated_configurations: Dict[str, Any] = {}
+                    updated_configurations[FEATURE_MANAGEMENT_KEY] = {}
+                    updated_configurations[FEATURE_MANAGEMENT_KEY][FEATURE_FLAG_KEY] = feature_flags
+                    self._dict.update(updated_configurations)
+                self._refresh_on_feature_flags = feature_flag_sentinel_keys
+                return True
+        return False
+
+    def _check_configuration_setting(
+        self, key, label, etag, headers, **kwargs
+    ) -> Tuple[bool, Union[ConfigurationSetting, None]]:
+        """
+        Checks if the configuration setting have been updated since the last refresh.
+
+        :keyword key: key to check for chances
+        :paramtype key: str
+        :keyword label: label to check for changes
+        :paramtype label: str
+        :keyword etag: etag to check for changes
+        :paramtype etag: str
+        :keyword headers: headers to use for the request
+        :paramtype headers: Mapping[str, str]
+        :return: A tuple with the first item being true/false if a change is detected. The second item is the updated
+        value if a change was detected.
+        :rtype: Tuple[bool, Union[ConfigurationSetting, None]]
+        """
+        try:
+            updated_sentinel = self._client.get_configuration_setting(  # type: ignore
+                key=key, label=label, etag=etag, match_condition=MatchConditions.IfModified, headers=headers, **kwargs
+            )
+            if updated_sentinel is not None:
+                logging.debug(
+                    "Refresh all triggered by key: %s label %s.",
+                    key,
+                    label,
+                )
+                return True, updated_sentinel
+        except HttpResponseError as e:
+            if e.status_code == 404:
+                if etag is not None:
+                    # 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)
+                    return True, None
+            else:
+                raise e
+        return False, None
+
     def _load_all(self, **kwargs):
+        configuration_settings, sentinel_keys = self._load_configuration_settings(**kwargs)
+        if self._feature_flag_enabled:
+            feature_flags, feature_flag_sentinel_keys = self._load_feature_flags(**kwargs)
+            configuration_settings[FEATURE_MANAGEMENT_KEY] = {}
+            configuration_settings[FEATURE_MANAGEMENT_KEY][FEATURE_FLAG_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:
             configurations = self._client.list_configuration_settings(
                 key_filter=select.key_filter, label_filter=select.label_filter, **kwargs
             )
             for config in configurations:
-                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:
+                    key = self._process_key_name(config)
+                    value = self._process_key_value(config)
                     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 = []
+        # Needs to be removed unknown keyword argument for list_configuration_settings
+        kwargs.pop("sentinel_keys", None)
+        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:
+                loaded_feature_flags.append(json.loads(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
@@ -551,8 +648,6 @@ def _process_key_name(self, config):
             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 +4,8 @@
 # license information.
 # -------------------------------------------------------------------------
 
-FEATURE_MANAGEMENT_KEY = "FeatureManagementFeatureFlags"
+FEATURE_MANAGEMENT_KEY = "FeatureManagement"
+FEATURE_FLAG_KEY = "FeatureFlags"
 FEATURE_FLAG_PREFIX = ".appconfig.featureflag/"
 
 EMPTY_LABEL = "\0"