feature: best practice dynamic configuration and feature flags (#25)

Author: ran-isenberg

.github/workflows/comment_issues.yml

@@ -0,0 +1,13 @@
+name: Comment when opened
+on:
+  issues:
+    types:
+      - opened
+jobs:
+  comment:
+    runs-on: ubuntu-latest
+    steps:
+      - run: gh issue comment $ISSUE --body "Thank you for opening this issue, we'll review it ASAP."
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ISSUE: ${{ github.event.issue.html_url }}

.github/workflows/dependabot.yml

@@ -0,0 +1,18 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    commit-message:
+      prefix: chore
+      include: scope
+
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    target-branch: "main"
+    commit-message:
+      prefix: chore
+      include: scope

.github/workflows/python-app.yml

@@ -18,11 +18,11 @@ jobs:
       - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
       - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
       - name: Check out repository code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Python 3.8
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v3
         with:
           python-version: "3.8"
       - name: Install dependencies
@@ -54,9 +54,27 @@ jobs:
           fail_ci_if_error: true # optional (default = false)
           verbose: false # optional (default = false)
           token: ${{ secrets.CODECOV_TOKEN }}
-      - run: echo "🍏 This job's status is ${{ job.status }}."
       - run: echo "Run CDK deploy to your AWS account"
       - run: echo "Run E2E"
       - run: echo "Update documentation"
-      - run: pip install mkdocs-material mkdocs-git-revision-date-plugin
-      - run: mkdocs gh-deploy --force
+      - run: echo "🍏 This job's status is ${{ job.status }}."
+
+  generate_docs_on_main:
+    name: generate_docs_on_main
+    runs-on: ubuntu-latest
+    needs: [build]
+    if: contains('refs/heads/main', github.ref)
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v3
+      - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
+      - uses: actions/checkout@v3
+      - name: Set up Python 3.8
+        uses: actions/setup-python@v3
+        with:
+          python-version: "3.8"
+      - name: Generate docs
+        run: |
+          python -m pip install --upgrade pip
+          pip install mkdocs-material mkdocs-git-revision-date-plugin
+          mkdocs gh-deploy --force

.github/workflows/semantic.yml

@@ -0,0 +1,13 @@
+# conventional commit types: https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json
+types:
+  - feature
+  - fix
+  - docs
+  - refactor
+  - perf
+  - test
+  - chore
+  - revert
+
+# Always validate the PR title
+titleOnly: true

.gitignore

@@ -245,3 +245,4 @@ $RECYCLE.BIN/
 .coverage
 cdk.out
 .build
+.vscode

cdk/aws_lambda_handler_cookbook/service_stack/configuration/__init__.py

@@ -0,0 +1,90 @@
+import json
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+import aws_cdk.aws_appconfig as appconfig
+from aws_lambda_handler_cookbook.service_stack.configuration.schema import FeatureFlagsConfiguration
+from constructs import Construct
+
+DEFAULT_DEPLOYMENT_STRATEGY = 'AppConfig.AllAtOnce'
+
+CUSTOM_ZERO_TIME_STRATEGY = 'zero'
+
+
+class ConfigurationStore(Construct):
+
+    def __init__(self, scope: Construct, id_: str, environment: str, service_name: str, configuration_name: str,
+                 deployment_strategy_id: Optional[str] = None) -> None:
+        """
+        This construct should be deployed in a different repo and have its own pipeline so updates can be decoupled from
+        running the service pipeline and without redeploying the service lambdas.
+
+        Args:
+            scope (Construct): The scope in which to define this construct.
+            id_ (str): The scoped construct ID. Must be unique amongst siblings. If the ID includes a path separator (``/``), then it will be replaced by double dash ``--``.
+            environment (str): environment name. Used for loading the corresponding JSON file to upload under 'configuration/json/{environment}_configuration.json'
+            service_name (str): application name.
+            configuration_name (str): configuration name
+            deployment_strategy_id (str, optional): AWS AppConfig deployment strategy.
+                                                    See https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-deployment-strategy.html
+                                                    Defaults to DEFAULT_DEPLOYMENT_STRATEGY.
+        """
+        super().__init__(scope, id_)
+
+        configuration_str = self._get_and_validate_configuration(environment)
+
+        self.config_app = appconfig.CfnApplication(
+            self,
+            id=service_name,
+            name=service_name,
+        )
+        self.config_env = appconfig.CfnEnvironment(
+            self,
+            id='env',
+            application_id=self.config_app.ref,
+            name=environment,
+        )
+        self.config_profile = appconfig.CfnConfigurationProfile(
+            self,
+            id='profile',
+            application_id=self.config_app.ref,
+            location_uri='hosted',
+            name=configuration_name,
+        )
+        self.hosted_cfg_version = appconfig.CfnHostedConfigurationVersion(
+            self,
+            'version',
+            application_id=self.config_app.ref,
+            configuration_profile_id=self.config_profile.ref,
+            content=configuration_str,
+            content_type='application/json',
+        )
+
+        self.cfn_deployment_strategy = appconfig.CfnDeploymentStrategy(
+            self,
+            CUSTOM_ZERO_TIME_STRATEGY,
+            deployment_duration_in_minutes=0,
+            growth_factor=100,
+            name=CUSTOM_ZERO_TIME_STRATEGY,
+            replicate_to='NONE',
+            description='zero minutes, zero bake, 100 growth all at once',
+            final_bake_time_in_minutes=0,
+        )
+
+        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=self.cfn_deployment_strategy.ref,
+            environment_id=self.config_env.ref,
+        )
+
+    def _get_and_validate_configuration(self, environment: str) -> str:
+        current = Path(__file__).parent
+        conf_filepath = current / (f'json/{environment}_configuration.json')
+        configuration_str = conf_filepath.read_text()
+        # validate configuration (check feature flags schema structure if exists)
+        parsed_configuration = FeatureFlagsConfiguration.parse_raw(configuration_str)
+        return configuration_str

cdk/aws_lambda_handler_cookbook/service_stack/configuration/configuration_construct.py

@@ -0,0 +1,26 @@
+{
+    "features": {
+        "premium_features": {
+            "default": false,
+            "rules": {
+                "enable premium features for this specific customer name": {
+                    "when_match": true,
+                    "conditions": [
+                        {
+                            "action": "EQUALS",
+                            "key": "customer_name",
+                            "value": "RanTheBuilder"
+                        }
+                    ]
+                }
+            }
+        },
+        "ten_percent_off_campaign": {
+            "default": true
+        }
+    },
+    "countries": [
+        "ISRAEL",
+        "USA"
+    ]
+}

cdk/aws_lambda_handler_cookbook/service_stack/configuration/json/dev_configuration.json

@@ -0,0 +1,17 @@
+from typing import Any, Dict, Optional
+
+from aws_lambda_powertools.utilities.feature_flags import SchemaValidator
+from pydantic import BaseModel, validator
+
+
+class FeatureFlagsConfiguration(BaseModel):
+    features: Optional[Dict[str, Any]]
+
+    @validator('features', pre=True)
+    def validate_features(cls, value):
+        validator = SchemaValidator(value)
+        try:
+            validator.validate()
+        except Exception as exc:
+            raise ValueError(str(exc))
+        return value

cdk/aws_lambda_handler_cookbook/service_stack/configuration/schema.py

@@ -14,6 +14,9 @@
 POWER_TOOLS_LOG_LEVEL = 'LOG_LEVEL'
 BUILD_FOLDER = '.build/lambdas/'
 COMMION_LAYER_BUILD_FOLDER = '.build/common_layer'
+ENVIRONMENT = 'dev'
+CONFIGURATION_NAME = 'my_conf'
+CONFIGURATION_MAX_AGE_MINUTES = '5'  # time to store appconfig conf in the cache before refetching it
 
 
 def get_stack_name() -> str: