fix(docs): Extract feature flag code examples

Changes:
- Extract code examples
- Run isort, black
- Correct line highlights
- Add make task

Related to:
- aws-powertools#1064

Author: michaelbrewer

Diff for: Makefile

@@ -90,3 +90,11 @@ changelog:
 
 mypy:
 	poetry run mypy --pretty aws_lambda_powertools
+
+format-examples:
+	poetry run isort docs/examples
+	poetry run black docs/examples/*/*/*.py
+
+lint-examples:
+	poetry run python3 -m py_compile docs/examples/*/*/*.py
+	cfn-lint docs/examples/*/*/*.yml

Diff for: docs/examples/utilities/feature_flags/app_config.py

@@ -0,0 +1,25 @@
+import jmespath
+from botocore.config import Config
+
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore
+
+boto_config = Config(read_timeout=10, retries={"total_max_attempts": 2})
+
+# Custom JMESPath functions
+class CustomFunctions(jmespath.functions.Functions):
+    @jmespath.functions.signature({"types": ["string"]})
+    def _func_special_decoder(self, s):
+        return my_custom_decoder_logic(s)
+
+
+custom_jmespath_options = {"custom_functions": CustomFunctions()}
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="configuration",
+    max_age=120,
+    envelope="features",
+    sdk_config=boto_config,
+    jmespath_options=custom_jmespath_options,
+)

Diff for: docs/examples/utilities/feature_flags/cache_config.py

@@ -0,0 +1,8 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="features",
+    max_age=300,
+)

Diff for: docs/examples/utilities/feature_flags/cdk_app.py

@@ -0,0 +1,58 @@
+import json
+
+import aws_cdk.aws_appconfig as appconfig
+from aws_cdk import core
+
+
+class SampleFeatureFlagStore(core.Construct):
+    def __init__(self, scope: core.Construct, id_: str) -> None:
+        super().__init__(scope, id_)
+
+        features_config = {
+            "premium_features": {
+                "default": False,
+                "rules": {
+                    "customer tier equals premium": {
+                        "when_match": True,
+                        "conditions": [{"action": "EQUALS", "key": "tier", "value": "premium"}],
+                    }
+                },
+            },
+            "ten_percent_off_campaign": {"default": True},
+        }
+
+        self.config_app = appconfig.CfnApplication(
+            self,
+            id="app",
+            name="product-catalogue",
+        )
+        self.config_env = appconfig.CfnEnvironment(
+            self,
+            id="env",
+            application_id=self.config_app.ref,
+            name="dev-env",
+        )
+        self.config_profile = appconfig.CfnConfigurationProfile(
+            self,
+            id="profile",
+            application_id=self.config_app.ref,
+            location_uri="hosted",
+            name="features",
+        )
+        self.hosted_cfg_version = appconfig.CfnHostedConfigurationVersion(
+            self,
+            "version",
+            application_id=self.config_app.ref,
+            configuration_profile_id=self.config_profile.ref,
+            content=json.dumps(features_config),
+            content_type="application/json",
+        )
+        self.app_config_deployment = appconfig.CfnDeployment(
+            self,
+            id="deploy",
+            application_id=self.config_app.ref,
+            configuration_profile_id=self.config_profile.ref,
+            configuration_version=self.hosted_cfg_version.ref,
+            deployment_strategy_id="AppConfig.AllAtOnce",
+            environment_id=self.config_env.ref,
+        )

Diff for: docs/examples/utilities/feature_flags/envelope.py

@@ -0,0 +1,8 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="configuration",
+    envelope="feature_flags",
+)

Diff for: docs/examples/utilities/feature_flags/get_enabled_features.py

@@ -0,0 +1,34 @@
+from aws_lambda_powertools.event_handler import APIGatewayRestResolver
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags
+
+app = APIGatewayRestResolver()
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="features",
+)
+feature_flags = FeatureFlags(store=app_config)
+
+
+@app.get("/products")
+def list_products():
+    ctx = {
+        **app.current_event.headers,
+        **app.current_event.json_body,
+    }
+
+    # all_features is evaluated to ["geo_customer_campaign", "ten_percent_off_campaign"]
+    all_features: list[str] = feature_flags.get_enabled_features(context=ctx)
+
+    if "geo_customer_campaign" in all_features:
+        # apply discounts based on geo
+        ...
+
+    if "ten_percent_off_campaign" in all_features:
+        # apply additional 10% for all customers
+        ...
+
+
+def lambda_handler(event, context):
+    return app.resolve(event, context)

Diff for: docs/examples/utilities/feature_flags/get_raw_configuration.py

@@ -0,0 +1,12 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="configuration",
+    envelope="feature_flags",
+)
+
+feature_flags = FeatureFlags(store=app_config)
+
+config = app_config.get_raw_configuration

Diff for: docs/examples/utilities/feature_flags/non_boolean_flag.py

@@ -0,0 +1,24 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="features",
+)
+
+feature_flags = FeatureFlags(store=app_config)
+
+
+def lambda_handler(event, context):
+    # Get customer's tier from incoming request
+    ctx = {"tier": event.get("tier", "standard")}
+
+    # Evaluate `has_premium_features` base don customer's tier
+    premium_features: list[str] = feature_flags.evaluate(
+        name="premium_features",
+        context=ctx,
+        default=False,
+    )
+    for feature in premium_features:
+        # enable premium features
+        ...

Diff for: docs/examples/utilities/feature_flags/single_feature_flag.py

@@ -0,0 +1,25 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="features",
+)
+
+feature_flags = FeatureFlags(store=app_config)
+
+
+def lambda_handler(event, context):
+    # Get customer's tier from incoming request
+    ctx = {"tier": event.get("tier", "standard")}
+
+    # Evaluate whether customer's tier has access to premium features
+    # based on `has_premium_features` rules
+    has_premium_features: bool = feature_flags.evaluate(
+        name="premium_features",
+        context=ctx,
+        default=False,
+    )
+    if has_premium_features:
+        # enable premium features
+        ...

Diff for: docs/examples/utilities/feature_flags/static_flag.py

@@ -0,0 +1,20 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags
+
+app_config = AppConfigStore(
+    environment="dev",
+    application="product-catalogue",
+    name="features",
+)
+
+feature_flags = FeatureFlags(store=app_config)
+
+
+def lambda_handler(event, context):
+    apply_discount: bool = feature_flags.evaluate(
+        name="ten_percent_off_campaign",
+        default=False,
+    )
+
+    if apply_discount:
+        # apply 10% discount to product
+        ...

Diff for: docs/examples/utilities/feature_flags/template.yml

@@ -0,0 +1,60 @@
+AWSTemplateFormatVersion: "2010-09-09"
+Description: Lambda Powertools Feature flags sample template
+Resources:
+  FeatureStoreApp:
+    Type: AWS::AppConfig::Application
+    Properties:
+      Description: "AppConfig Application for feature toggles"
+      Name: product-catalogue
+
+  FeatureStoreDevEnv:
+    Type: AWS::AppConfig::Environment
+    Properties:
+      ApplicationId: !Ref FeatureStoreApp
+      Description: "Development Environment for the App Config Store"
+      Name: dev
+
+  FeatureStoreConfigProfile:
+    Type: AWS::AppConfig::ConfigurationProfile
+    Properties:
+      ApplicationId: !Ref FeatureStoreApp
+      Name: features
+      LocationUri: "hosted"
+
+  HostedConfigVersion:
+    Type: AWS::AppConfig::HostedConfigurationVersion
+    Properties:
+      ApplicationId: !Ref FeatureStoreApp
+      ConfigurationProfileId: !Ref FeatureStoreConfigProfile
+      Description: 'A sample hosted configuration version'
+      Content: |
+        {
+              "premium_features": {
+                "default": false,
+                "rules": {
+                  "customer tier equals premium": {
+                    "when_match": true,
+                    "conditions": [
+                      {
+                        "action": "EQUALS",
+                        "key": "tier",
+                        "value": "premium"
+                      }
+                    ]
+                  }
+                }
+              },
+              "ten_percent_off_campaign": {
+                "default": false
+              }
+          }
+      ContentType: 'application/json'
+
+  ConfigDeployment:
+    Type: AWS::AppConfig::Deployment
+    Properties:
+      ApplicationId: !Ref FeatureStoreApp
+      ConfigurationProfileId: !Ref FeatureStoreConfigProfile
+      ConfigurationVersion: !Ref HostedConfigVersion
+      DeploymentStrategyId: "AppConfig.AllAtOnce"
+      EnvironmentId: !Ref FeatureStoreDevEnv

Diff for: docs/examples/utilities/feature_flags/unit_test.py

@@ -0,0 +1,48 @@
+from aws_lambda_powertools.utilities.feature_flags import AppConfigStore, FeatureFlags, RuleAction
+
+
+def init_feature_flags(mocker, mock_schema, envelope="") -> FeatureFlags:
+    """Mock AppConfig Store get_configuration method to use mock schema instead"""
+
+    method_to_mock = "aws_lambda_powertools.utilities.feature_flags.AppConfigStore.get_configuration"
+    mocked_get_conf = mocker.patch(method_to_mock)
+    mocked_get_conf.return_value = mock_schema
+
+    app_conf_store = AppConfigStore(
+        environment="test_env",
+        application="test_app",
+        name="test_conf_name",
+        envelope=envelope,
+    )
+
+    return FeatureFlags(store=app_conf_store)
+
+
+def test_flags_condition_match(mocker):
+    # GIVEN
+    expected_value = True
+    mocked_app_config_schema = {
+        "my_feature": {
+            "default": expected_value,
+            "rules": {
+                "tenant id equals 12345": {
+                    "when_match": True,
+                    "conditions": [
+                        {
+                            "action": RuleAction.EQUALS.value,
+                            "key": "tenant_id",
+                            "value": "12345",
+                        }
+                    ],
+                }
+            },
+        }
+    }
+
+    # WHEN
+    ctx = {"tenant_id": "12345", "username": "a"}
+    feature_flags = init_feature_flags(mocker=mocker, mock_schema=mocked_app_config_schema)
+    flag = feature_flags.evaluate(name="my_feature", context=ctx, default=False)
+
+    # THEN
+    assert flag == expected_value