AWS ‐ SAM (Serverless Application Model)

What is AWS SAM?

AWS Serverless Application Model (SAM) is an open-source framework designed to build, test, and deploy serverless applications on AWS. It extends AWS CloudFormation by providing shorthand syntax for defining Lambda functions, API Gateway, DynamoDB tables, and other serverless resources.

With AWS SAM, you can:

• Define serverless applications using a simplified YAML syntax.
• Build locally using the AWS SAM CLI (e.g., test Lambda, invoke APIs, debug).
• Deploy applications with built-in best practices.
• Use AWS SAM Accelerate for faster deployments.

AWS SAM vs. AWS CloudFormation

Feature	AWS SAM	AWS CloudFormation
Purpose	Designed for serverless applications	Manages all AWS infrastructure
Syntax	Simplified YAML with built-in serverless components	More verbose, requires manual setup for serverless
Local Testing	Supports local testing/debugging using SAM CLI	No built-in local testing
CLI Features	sam build, sam deploy, sam local invoke	Uses aws cloudformation deploy
Transform	Uses AWS::Serverless-2016-10-31 transform to convert SAM templates into standard CloudFormation	No transformation required
Deployment Speed	Faster for serverless apps using incremental changes	Slower due to full-stack deployments
Extensibility	Can use CloudFormation resources inside a SAM template	Fully flexible for all AWS resources

When Should You Use AWS SAM?

✅ Use AWS SAM when:

• Building serverless applications (Lambda, API Gateway, DynamoDB, Step Functions).
• Need local testing/debugging before deployment.
• Want a simplified YAML template for infrastructure.
• Need faster deployments with sam accelerate.

❌ Use CloudFormation when:

• Managing a full-stack AWS infrastructure (e.g., EC2, RDS, VPC, networking).
• Defining complex dependencies across AWS services.
• Working with hybrid architectures (serverless + traditional).

Conclusion

AWS SAM is CloudFormation for serverless applications with added benefits like local testing and simplified configuration. If you're building a serverless app, use SAM. If managing a broader AWS infrastructure, use CloudFormation.