Feature flags with AWS AppConfig provide a powerful mechanism for controlling application behavior without requiring code deployments. AppConfig is a capability of AWS Systems Manager that enables developers to safely deploy configuration changes and feature flags to applications at scale.
Feature…Feature flags with AWS AppConfig provide a powerful mechanism for controlling application behavior without requiring code deployments. AppConfig is a capability of AWS Systems Manager that enables developers to safely deploy configuration changes and feature flags to applications at scale.
Feature flags, also known as feature toggles, allow you to enable or disable specific functionality in your application dynamically. With AppConfig, you can manage these flags centrally and roll them out gradually to users, reducing the risk associated with new feature releases.
Key components of AppConfig feature flags include:
1. **Application**: Represents your application in AppConfig, serving as a logical container for configuration data.
2. **Environment**: Defines where configurations are deployed, such as development, staging, or production.
3. **Configuration Profile**: Contains the feature flag definitions and their values, stored as JSON or YAML.
4. **Deployment Strategy**: Controls how configurations are rolled out, including deployment duration and growth rate percentage.
AppConfig supports gradual deployments with built-in rollback capabilities. If issues arise during deployment, AppConfig can automatically revert to the previous configuration based on CloudWatch alarms you define.
To implement feature flags, your application retrieves configuration data through the AppConfig agent or by calling the GetLatestConfiguration API. The agent caches configurations locally, reducing latency and API calls.
Benefits include:
- Separating feature releases from code deployments
- A/B testing capabilities
- Gradual rollouts to minimize blast radius
- Quick rollback when problems occur
- Centralized feature management
For the AWS Developer Associate exam, understand that AppConfig integrates with Lambda extensions for serverless applications, supports validators to ensure configuration correctness before deployment, and provides deployment strategies like Linear, Exponential, and AllAtOnce for different rollout scenarios.
Feature Flags with AWS AppConfig
What Are Feature Flags with AppConfig?
Feature flags (also known as feature toggles) are a software development technique that allows you to enable or disable features in your application without deploying new code. AWS AppConfig is a capability of AWS Systems Manager that helps you create, manage, and deploy application configurations, including feature flags, across your applications.
Why Are Feature Flags Important?
Feature flags provide several critical benefits:
• Safe Deployments: Roll out new features gradually to a subset of users before full release • Quick Rollback: Disable problematic features in seconds rather than redeploying code • A/B Testing: Test different feature variations with different user segments • Operational Control: Enable or disable features based on system load or business requirements • Decoupled Deployment: Separate code deployment from feature release
How AppConfig Works
AppConfig follows a structured workflow:
1. Application: Create an application in AppConfig that represents your software
2. Environment: Define environments (dev, staging, production) where configurations will be deployed
3. Configuration Profile: Create a configuration profile that stores your feature flags as JSON, YAML, or freeform data
4. Deployment Strategy: Define how configurations are rolled out (linear, exponential, or all-at-once)
5. Deployment: Deploy the configuration to your environment using the chosen strategy
Key Components
• Configuration Store: Can be stored in AppConfig hosted configuration, S3, SSM Parameter Store, or SSM Documents • Validators: JSON Schema or Lambda validators ensure configuration correctness before deployment • Deployment Strategies: Control rollout speed with options like Linear50PercentEvery30Seconds or AllAtOnce • Extensions: Add actions like notifications or backups during deployment lifecycle
Feature Flag Types in AppConfig
AppConfig supports AWS AppConfig Feature Flags as a specific configuration type with: • Boolean flags (on/off) • String, number, or JSON attribute values • Built-in validation • Targeting rules for specific user segments
Integration with Applications
Applications retrieve feature flags using: • AWS SDK calls to GetLatestConfiguration API • AppConfig Agent (sidecar or Lambda layer) for caching and polling • The agent reduces API calls and provides local caching
Exam Tips: Answering Questions on Feature Flags with AppConfig
Scenario Recognition: • When a question mentions toggling features on/off in production, think AppConfig feature flags • Questions about gradual feature rollouts or canary releases point to AppConfig deployment strategies • Scenarios requiring configuration changes across multiple environments suggest AppConfig
Key Differentiators: • AppConfig is for dynamic configuration that changes during runtime • Parameter Store is for static configuration and secrets • AppConfig provides deployment strategies that Parameter Store does not
Remember These Points: • Deployment strategies allow gradual rollout with automatic rollback on errors • Validators prevent deploying invalid configurations • AppConfig integrates with CloudWatch alarms to trigger automatic rollback • Feature flags in AppConfig use JSON format with attributes and constraints
Common Exam Scenarios: • Enabling features for specific user segments = AppConfig with targeting rules • Rolling back a feature causing errors = AppConfig with CloudWatch alarm integration • Deploying configuration changes with minimal risk = Linear deployment strategy • Reducing API calls when fetching configuration = AppConfig Agent with caching
Watch Out For: • Questions may try to confuse AppConfig with CodeDeploy - remember AppConfig is for configuration, CodeDeploy is for application code • AppConfig hosted configuration has a 1MB size limit per configuration version