Serverless Application Model (SAM)

The AWS Serverless Application Model (SAM) is an open-source framework that simplifies the process of building, testing, and deploying serverless applications on AWS.

By providing a shorthand syntax to express functions, APIs, databases, and event source mappings, SAM reduces the complexity involved in managing the infrastructure behind serverless workloads.

With deep integration into AWS services like AWS Lambda, Amazon API Gateway, DynamoDB, and more, SAM streamlines the developer experience by enabling infrastructure as code in a concise and maintainable format. It supports local development and debugging as well, fostering rapid iteration and deployment.

What is AWS SAM?

AWS SAM extends AWS CloudFormation with simplified syntax and tooling aimed specifically at serverless applications. Instead of verbose resource definitions, developers can declare serverless components with fewer lines of code, focusing on application logic rather than underlying infrastructure.

Key Features of AWS SAM

1. Simplified Template Syntax: SAM templates are written in YAML and provide higher-level abstractions for AWS Lambda functions, API Gateway APIs, DynamoDB tables, and event sources.

2. Local Development and Testing: The SAM CLI allows developers to locally build, test, and debug Lambda functions with support for API Gateway emulation and event simulation.

3. Code Packaging and Deployment: SAM automates the packaging of source code and dependencies and deploys the application stack using AWS CloudFormation, maintaining full infrastructure management capabilities.

4. Function Versioning and Aliases: Supports Lambda function versioning and aliases for safer deployment strategies like blue-green or canary updates.

5. Policy Templates: Predefined IAM policy templates simplify setting least-privilege permissions for Lambda functions.

6. Integration with CI/CD Pipelines: SAM fits naturally into continuous integration and delivery workflows, supporting automated build and deployment pipelines.

SAM Template Structure and Components

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Simplified Example SAM Template Snippet

Resources:

  MyFunction:

    Type: AWS::Serverless::Function

    Properties:

      Handler: index.handler

      Runtime: nodejs18.x

      CodeUri: ./src

      Policies: AWSLambdaBasicExecutionRole

      Events:

        MyApi:

          Type: Api

          Properties:

            Path: /hello

            Method: get

Benefits of Using AWS SAM

With AWS SAM, developers can focus more on code and innovation rather than managing infrastructure. Listed below are the primary benefits that make SAM a powerful tool for creating and managing serverless solutions:

• Developer Productivity: Reduces boilerplate and accelerates serverless application creation.
• Consistency and Best Practices: Enforces best practices for permissions, versioning, and deployment.
• Comprehensive Tooling: SAM CLI supports local debugging, step-through execution, and automated packaging.
• Scalability: Enables easy scaling of serverless applications with integrated event source support.
• Community and Ecosystem: Backed by an active community and continuously evolving with AWS services.

Best Practices ( Image )

• Use policy templates to enforce the principle of least privilege.
• Modularize large applications into multiple SAM templates.
• Leverage SAM CLI for local testing before cloud deployment.
• Incorporate SAM into CI/CD pipelines for reliable delivery.
• Use versioning and aliases to implement traffic shifting strategies