• https://chatgpt.com/c/6763704a-0a24-800d-b9a2-1866b9931f4d
• https://github.com/aws/aws-sam-cli-app-templates

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SAM (Serverless Application Model)

• serverless : Lambda, API Gateway, DynamoDB, step function, eventbridge,CW, etc

A. Intro

- Framework for simplifying serverless application deployment - AWS SAM templates (YAML/JSON). - defines resources - AWS::Serverless::Function - AWS::Serverless::Api - AWS::Serverless::SimpleTable

B. sam cli

• sam init
• same build
• sam package : creates cloudformation stack
• --template-file
• --output-template-file

• --s3-bucket

  • zip and upload (template and code) to s3

• sam deploy : deploy cf stack

• use CodeDeploy to deploy Lambda functions

• sam sync --watch

• 

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C. Hands ON

1. Deploy lambda function-v1 with API-gateway

• added env var from template
• added polices from template

  AWSTemplateFormatVersion: '2010-09-09'
  Transform: AWS::Serverless-2016-10-31
  Description: A simple AWS SAM example
  
  Resources:
    HelloWorldFunction:
      Type: AWS::Serverless::Function
      Properties:
        Handler: app.lambda_handler
        Runtime: python3.11
        CodeUri: lambda/
  
        # Environmnet var
        Environment:
          Variables:
            # TABLE_NAME: HelloWorldTable
            TABLE_NAME: !Ref HelloWorldTable
            REGION_NAME: !Ref AWS::Region
  
        # polices to perform CRUD on table    
        Policies:
          - DynamoDBCrudPolicy:
              TableName: !Ref HelloWorldTable
  
        # expose as API gateway      
        Events:
          HelloWorldApi:
            Type: AWS::Serverless::Api
            Properties:
              Path: /hello
              Method: get
              StageName: prod
              Cors:
                AllowMethods: "'GET,POST'"
                AllowHeaders: "'Content-Type'"
                AllowOrigin: "'*'"
  

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2. add DynamoDB table

Resources:  
  HelloWorldTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: HelloWorldTable
      PrimaryKey:
        Name: id
        Type: String
      ProvisionedThroughput:
        ReadCapacityUnits: 5
        WriteCapacityUnits: 5

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3. Deploy lambda function-v2 using codeDeploy(blue/green)

• update lambda code
• update template

  AutoPublishAlias: live  
  DeploymentPreference:
      Type: Canary10Percent10Minutes # sam will use codeDeploy
      Alarms:
        - !Ref DeploymentFailureAlarm # configure **cloudwatch alarm**
  

• sam build

• sam deploy -guided

• sam will automatically update CF template with codeDeploy + CW:alarm

• deployment type (quick revision again) 00_start.md
  • in-place
  • blue/green
  • traffic routing:
    • canary
    • linear
    • allAtOnce
  • traffic hook (optional)
    • pre-traffic hook - lambda-hook-fn-1
    • post-traffic hook - lambda-hook-fn-2

  # update lamda
  AutoPublishAlias: live  
  DeploymentPreference:
      Type: Canary10Percent10Minutes
      Alarms:
        - !Ref DeploymentFailureAlarm

  # Another resource
  DeploymentFailureAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmName: DeploymentFailureAlarm
      MetricName: Errors
      Namespace: AWS/Lambda
      Statistic: Sum
      Period: 60
      EvaluationPeriods: 1
      Threshold: 1
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: FunctionName
          Value: !Ref HelloWorldFunction
        - Name: Resource
          Value: !Join ["", [!Ref HelloWorldFunction, ":", "live"]] 

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D. sam local

• install AWSToolkit as well
• Provides a lambda-like execution environment locally

• Locally build, test, and debug your serverless applications that are defined using AWS SAM templates

• sam local start-lambda + sam local invoke

• sam local invoke –t MyCDKStack.template.json myFunction-1
• sam local start-api
• sam local generate-event

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D. sam environment