SAM

• 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…
• SAM can use CodeDeploy to deploy Lambda functions
• SAM can help you to run Lambda, API Gateway, DynamoDB locally

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: sam deploy (optionally preceded by “sam package”)
• Quickly sync local changes to AWS Lambda (SAM Accelerate): sam sync --watch

SAM Deployment

Accelerate (sam sync)

• SAM Accelerate is a set of features to reduce latency while deploying resources to AWS
• sam sync
  • Synchronizes your project declared in SAM templates to AWS
  • Synchronizes code changes to AWS without updating infrastructure (uses service APIs & bypass CloudFormation)

Examples

• sam sync (no options)
  • Synchronize code and infrastructure
• sam sync --code
  • Synchronize code changes without updating infrastructure (bypass CloudFormation, update in seconds)
• sam sync --code --resource AWS::Serverless::Function
  • Synchronize only all Lambda functions and their dependencies
• sam sync --code --resource-id HelloWorldLambdaFunction
  • Synchronize only a specific resource by its ID
• sam sync --watch
  • Monitor for file changes and automatically synchronize when changes are detected
  • If changes include configuration, it uses sam sync
  • If changes are code only, it uses sam sync --code

CLI Debugging

• Locally build, test, and debug your serverless applications that are defined using AWS SAM templates
• Provides a lambda-like execution environment locally
• SAM CLI + AWS Toolkits => step-through and debug your code
• Supported IDEs: AWS Cloud9, Visual Studio Code, JetBrains, PyCharm, IntelliJ, …
• AWS Toolkits: IDE plugins which allows you to build, test, debug, deploy, and invoke Lambda functions built using AWS SAM

SAM Policy Templates

• List of templates to apply permissions to your Lambda Functions
• Important examples:
  • S3ReadPolicy: Gives read only permissions to objects in S3
  • SQSPollerPolicy: Allows to poll an SQS queue
  • DynamoDBCrudPolicy: CRUD = create read update delete

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

• AutoPublishAlias
  • Detects when new code is being deployed
  • Creates and publishes an updated version of that function with the latest code
  • Points the alias to the updated version of the Lambda function
• DeploymentPreference
  • Canary, Linear, AllAtOnce
• Alarms
  • Alarms that can trigger a rollback
• Hooks
  • Pre and post traffic shifting Lambda functions to test your deployment

Local Capabilities

• Locally start AWS Lambda
  • sam local start-lambda
  • Starts a local endpoint that emulates AWS Lambda
  • Can run automated tests against this local endpoint
• Locally Invoke Lambda Function
  • sam local invoke
  • Invoke Lambda function with payload once and quit after invocation completes
  • Helpful for generating test cases
  • If the function make API calls to AWS, make sure you are using the correct --profile option
• Locally Start an API Gateway Endpoint
  • sam local start-api
  • Starts a local HTTP server that hosts all your functions
  • Changes to functions are automatically reloaded
• Generate AWS Events for Lambda Functions
  • sam local generate-event
  • Generate sample payloads for event sources
  • S3, API Gateway, SNS, Kinesis, DynamoDB…

Multiple Environments