AWS Serverless Application Model

• SAM: Serverless Application Model
• Framework for developing and deploying serverless applications
• All the configuration is YAML code
• Generate complex CloudFormation from simple SAM YAML file
• Supports anything from CloudFormation: Outputs, Mappings, Parameters, Resources...
• Only two commands to deploy to AWS
• SAM can use CodeDeploy to deploy Lambda functions
• SAM can help you to run Lambda, API Gateway, DynamoDB locally

AWS SAM - Recipe

• Transform Header indicates it's SAM template:
  • Transform: 'AWS::Serverless-2016-10-31'
• Write Code:
  • AWS::Serverless::Function
  • AWS::Serverless::Api
  • AWS::Serverless::SimpleTable
• Package & Deploy:
  • aws cloudformation package / sam package
  • aws cloudformation deploy / sam deploy

Deep dive into SAM deployment

1. aws cloudformation package:

   • SAM Template YAML file --Transform--> Generated Template CloudFormation YAML
   • Application Code + Swagger File (optional) --Zip and upload--> Code S3 bucket --reference--> Generated Template CloudFormation YAML

2. aws cloudformation deploy:

   • Generated Template CloudFormation YAML --Create and execute change set--> AWS CloudFormation --> Stack

• To installing the SAM CLI follow the steps provided in AWS SAM CLI - Installation

• See example application on how to use SAM by visiting AWS SAM Examples

SAM and CodeDeploy

• SAM framework natively uses CodeDeploy to update Lambda functions
• Traffic Shifting feature
• Pre and Post traffic hooks features to validate deployment (before the traffic shift starts and after it ends)
• Easy & automated rollback using CloudWatch Alarms

SAM - Exam Summary

• SAM is built on CloudFormation
• SAM requires the Transform and Resources sections
• Commands to know:
  • sam build: fetch dependencies and create local deployment artifacts
  • sam package: package and upload to Amazon S3, generate CF template
  • sam deploy: deploy to CloudFormation
• SAM Policy templates for easy IAM policy definition
• SAM is integrated with CodeDeploy to do deploy to Lambda aliases

Serverless Application Repository (SAR)

• Managed repository for serverless applications
• The applications are packaged using SAM
• Build and publish applications that can be re-used by organizations
• Can share publicly
• Can share with specific AWS accounts
• This prevents duplicate work, and just go straight to publishing
• Application settings and behaviour can be customized using Environment variables