Best Practices for Serverless Technologies in AWS

This article outlines best practices for using serverless technologies within the Amazon Web Services (AWS) ecosystem. It highlights key aspects of design, development, deployment, security, and operations to help you build scalable, cost-effective, and resilient serverless applications. Following these guidelines will enable you to maximise the benefits of serverless computing while steering clear of common pitfalls.

1. Design Principles

• Embrace Microservices: Decompose your application into small, independent, and loosely coupled microservices. Each microservice should perform a specific function and communicate with others through well-defined APIs. This approach enhances scalability, maintainability, and fault isolation.

• Event-Driven Architecture: Design your application around events. Services react to events triggered by other services or external sources. AWS services like EventBridge, SQS, and SNS facilitate event-driven communication.

• Stateless Functions: Design your Lambda functions to be stateless. Avoid storing any persistent data within the function's execution environment. Instead, rely on external data stores like DynamoDB, S3, or RDS. This ensures scalability and simplifies management.

• API Gateway as a Facade: Use API Gateway to expose your serverless backend as a set of RESTful APIs. API Gateway handles authentication, authorisation, request validation, and rate limiting, providing a secure and scalable entry point for your application.

• Optimise for Cold Starts: Minimise cold start latency by keeping your Lambda function's deployment package small, using a supported runtime, and avoiding unnecessary dependencies. Consider using provisioned concurrency for latency-sensitive applications.

2. Development Practices

• Infrastructure as Code (IaC): Define your infrastructure using code, such as AWS CloudFormation, AWS CDK, or Terraform. This allows you to automate the creation and management of your serverless resources, ensuring consistency and repeatability.

• Automated Testing: Implement a comprehensive testing strategy that includes unit tests, integration tests, and end-to-end tests. Use tools like Jest, Mocha, or Pytest to automate your testing process.

• Continuous Integration and Continuous Delivery (CI/CD): Set up a CI/CD pipeline to automate the build, test, and deployment of your serverless applications. Use tools like AWS CodePipeline, AWS CodeBuild, and AWS CodeDeploy to streamline your development workflow.

• Dependency Management: Use a dependency management tool like npm, pip, or Maven to manage your project's dependencies. This ensures that your application has the correct versions of all required libraries and frameworks.

• Logging and Monitoring: Implement robust logging and monitoring to track the performance and health of your serverless applications. Use AWS CloudWatch Logs, AWS X-Ray, and AWS CloudWatch Metrics to collect and analyse logs, traces, and metrics.

3. Deployment Strategies

• Blue/Green Deployments: Use blue/green deployments to minimise downtime during deployments. Deploy the new version of your application to a separate environment (the "green" environment) and then switch traffic to the new environment once it has been verified.

• Canary Deployments: Use canary deployments to gradually roll out new features to a small subset of users. Monitor the performance of the new features and roll them out to more users if they are performing well.

• Automated Rollbacks: Implement automated rollbacks to quickly revert to a previous version of your application if a deployment fails.

• Versioning: Use versioning to manage different versions of your Lambda functions and API Gateway APIs. This allows you to easily roll back to a previous version if necessary.

• Deployment Packages: Keep your deployment packages small to reduce deployment time and cold start latency. Remove unnecessary files and dependencies from your deployment packages.

4. Security Considerations

• Principle of Least Privilege: Grant your Lambda functions and other serverless resources only the permissions they need to perform their tasks. Use IAM roles and policies to enforce the principle of least privilege.

• Secure API Gateway: Secure your API Gateway APIs with authentication and authorisation. Use API keys, IAM roles, or Cognito to control access to your APIs.

• Input Validation: Validate all input to your Lambda functions to prevent injection attacks and other security vulnerabilities.

• Encryption: Encrypt sensitive data at rest and in transit. Use AWS KMS to manage encryption keys.

• Vulnerability Scanning: Regularly scan your serverless applications for security vulnerabilities. Use tools like AWS Inspector or third-party vulnerability scanners.

• Network Security: Secure your serverless applications by placing them in a private VPC and using security groups to control network traffic.

5. Operational Excellence

• Monitoring and Alerting: Set up comprehensive monitoring and alerting to detect and respond to issues in your serverless applications. Use AWS CloudWatch Alarms to trigger alerts based on metrics.

• Error Handling: Implement robust error handling to gracefully handle errors and prevent cascading failures. Use try-catch blocks and error logging to capture and diagnose errors.

• Retry Mechanisms: Implement retry mechanisms to automatically retry failed requests. Use exponential backoff to avoid overwhelming downstream services.

• Dead Letter Queues (DLQs): Use DLQs to capture messages that cannot be processed. This allows you to investigate and resolve the root cause of the failures.

• Cost Optimisation: Monitor your serverless costs and optimise your applications to reduce costs. Use AWS Cost Explorer to analyse your costs and identify areas for improvement. Consider using reserved concurrency for Lambda functions to reduce costs for predictable workloads.

6. Specific AWS Services Best Practices

AWS Lambda:

• Optimise function size and execution time.

• Use environment variables for configuration.

• Leverage Lambda Layers for shared code.

• Consider provisioned concurrency for latency-sensitive applications.

API Gateway:

• Use caching to improve performance.

• Implement request validation to prevent invalid requests.

• Use throttling to protect your backend services.

• Enable API Gateway logging for debugging and auditing.

DynamoDB:

• Choose the appropriate partition key.

• Use global secondary indexes to optimise queries.

• Use DynamoDB Accelerator (DAX) for caching.

• Monitor DynamoDB capacity and adjust as needed.

S3:

• Use appropriate storage classes (e.g., Standard, Intelligent-Tiering, Glacier).

• Enable versioning for data protection.

• Use lifecycle policies to manage data retention.

• Secure your S3 buckets with access control lists (ACLs) and bucket policies.

EventBridge:

• Use event filtering to route events to the correct targets.

• Use event transformation to modify events before they are sent to targets.

• Monitor EventBridge rules and targets for errors.

SQS/SNS:

• Use message attributes for metadata.

• Configure dead-letter queues for failed messages.

• Use message batching to improve throughput.

• Encrypt messages in transit and at rest.

By adhering to these best practices, you can build robust, scalable, and cost-effective serverless applications on AWS. Remember to continuously monitor and optimise your applications to ensure they are meeting your business needs.