I. What is AWS SAM?

• Definition: Open-source framework to streamline building and deploying serverless applications on AWS.
• Simplifies resource creation/management, reducing complexity of traditional architectures.
• Components:
  • SAM Templates:
    • Configuration files (YAML or JSON) specifying serverless resources (Lambda, API Gateway, DynamoDB).
    • Extension of AWS CloudFormation templates with simplified syntax for serverless.
    • Seamlessly transforms into CloudFormation syntax during deployment.
    • Supports all CloudFormation template items (Outputs, Mappings, Parameters).
    • Identified by Transform: 'AWS::Serverless-2016-10-31' header.
  • SAM CLI:
    • Vital tool for local development, testing, and debugging of serverless apps.
    • Provides Lambda-like execution environment for local testing.
    • Used for building, testing, and deploying applications to AWS.
• Offers shorthand syntax for functions, APIs, databases, event source mappings.

II. Key Benefits of AWS SAM

• Integration with Development Tools:
  • Seamlessly works with IDEs (PyCharm, IntelliJ, VS Code).
  • Integrates with AWS serverless tools (Serverless Application Repository, Cloud9 IDE).
  • Leverages AWS CodeBuild, CodeDeploy, CodePipeline for CI/CD pipelines.
• Local Testing and Debugging:
  • SAM CLI accelerates development cycle by providing immediate feedback.
  • Allows local build, test, and debug of applications defined by SAM templates.
• Built on AWS CloudFormation:
  • Extension of CloudFormation, allowing use of its powerful features.
• Built-in Best Practices:
  • Incorporates application lifecycle management (safe deployments, rollback capabilities).
  • Enables infrastructure as code for code reviews.
  • Facilitates gradual deployments via AWS CodeDeploy and tracing using AWS X-Ray with minimal configuration.

III. Disadvantages of AWS SAM

• API Gateway Configuration: Can be restrictive compared to manual or Serverless Framework configurations.
• Community of Plugin Creators: Fewer plugins available compared to Serverless Framework due to narrower focus and relative newness.

IV. Building a Serverless Application with AWS SAM

• Installation: SAM CLI installed via package managers (Homebrew, pip).
• Sample Apps: AWS provides numerous samples on GitHub.
• Building: Use sam build command after creating template and code.
• Deployment Details:
  • SAM template is YAML, declares all AWS resources for serverless app.
  • Transform: 'AWS::Serverless-2016-10-31' header indicates SAM template.
  • Resource Types (Examples):
    • AWS::Serverless::Function (AWS Lambda)
    • AWS::Serverless::Api (API Gateway REST API)
    • AWS::Serverless::SimpleTable (DynamoDB)
    • AWS::Serverless::Application (Serverless Application Repository)
    • AWS::Serverless::HttpApi (API Gateway HTTP API)
    • AWS::Serverless::LayerVersion (Lambda layers)
  • Deployment Commands (Two-step process):
    • sam package then sam deploy
    • OR aws cloudformation package then aws cloudformation deploy
  • SAM Policy Templates: List of templates to apply permissions to Lambda functions (e.g., S3ReadPolicy, SQSPollerPolicy, DynamoDBCrudPolicy).
• Testing:
  • Locally: Use sam local command.
  • In AWS: Invoke Lambda function manually or create test events in Lambda console.

V. Serverless Application Repository

• Centralized Hub: Managed repository for serverless applications.
• Fosters collaboration, allows storing/sharing reusable apps.
• Eliminates conventional deployment steps (cloning, building, packaging, publishing).
• Users can incorporate pre-built apps into serverless architectures.
• Streamlines development, mitigates duplication, promotes best practices, accelerates time-to-market.
• Security: Integrates with AWS IAM for granular resource-level control.
• Flexible sharing: Publicly or privately with specific AWS accounts.

VI. AWS SAM vs. Serverless Framework

• Both simplify defining and deploying serverless applications.
• Serverless Framework: Provider-agnostic (multi-cloud).
• AWS SAM: AWS-specific service with deep integration and support for AWS services.
• Choice depends on project needs and context.

Important Exam Tips for AWS Developer Associate

• CloudFormation Integration: Understand that SAM is an extension of CloudFormation. Any CloudFormation resource can be used in a SAM template.
• Local Development: Emphasize the SAM CLI's ability to build, test, and debug locally, which is crucial for developer productivity.
• Deployment Flow: Remember the two-step package and deploy process (or their CloudFormation equivalents).
• Transform Header: Key identifier for a SAM template.
• Resource Types: Be familiar with common AWS::Serverless:: resource types and what AWS service they map to (e.g., Function -> Lambda, Api -> API Gateway).
• Policy Templates: Know that SAM provides built-in policy templates to easily grant permissions to Lambda functions.
• X-Ray and CodeDeploy Integration: SAM simplifies enabling these for tracing and safe deployments.
• Serverless Application Repository: Understand its purpose as a hub for reusable serverless applications and its benefits (collaboration, accelerated development).
• SAM vs. Serverless Framework: Key differentiator is AWS-specific (SAM) vs. provider-agnostic (Serverless Framework).