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README.md Copy Chapter

AWS SAM transform


The AWS Serverless Application Model (AWS SAM) transform is a AWS CloudFormation macro that transforms SAM templates into CloudFormation templates.

To use the SAM transform, add AWS::Serverless-2016-10-31 to the Transform section of your CloudFormation template.

Benefits of using the SAM transform include:

- Built-in best practices and sane defaults.
- Local testing and debugging with the AWS SAM CLI.
- Extension of the CloudFormation template syntax.

Getting started Copy Chapter

Save the following as template.yaml:

Transform: AWS::Serverless-2016-10-31
Resources:
  MyFunction:
    Type: AWS::Serverless::Function
    Properties:
      Runtime: nodejs24.x
      Handler: index.handler
      InlineCode: |
        exports.handler = async (event) => {
          console.log(event);
        }

And deploy it with the SAM CLI:

sam sync --stack-name sam-app

The AWS::Serverless::Function resource will create a AWS Lambda function that logs events it receives.

Under the hood, the template is transformed into the JSON equivalent of the following CloudFormation template:

Resources:
  MyFunction:
    Type: AWS::Lambda::Function
    Properties:
      Code:
        ZipFile: |
          exports.handler = async (event) => {
            console.log(event);
          }
      Handler: index.handler
      Role: !GetAtt MyFunctionRole.Arn
      Runtime: nodejs24.x
      Tags:
        - Key: lambda:createdBy
          Value: SAM
  MyFunctionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Action:
              - sts:AssumeRole
            Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Tags:
        - Key: lambda:createdBy
          Value: SAM

For a more thorough introduction, see the this tutorial in the Developer Guide.

Contributing Copy Chapter

Setting up development environment Copy Section

You'll need to have Python 3.8+ installed.

Create a virtual environment:

python3 -m venv .venv
source .venv/bin/activate

Set up dependencies:

make init

Run tests:

make pr

Getting help Copy Chapter

The best way to interact with the team is through GitHub. You can either create an issue or start a discussion.

You can also join the #samdev channel on Slack.

Learn more Copy Chapter

Workshops and tutorials Copy Section

- The Complete AWS SAM Workshop
- AWS Serverless Developer Experience Workshop
- Deploying a "Hello, World!" application
- Testing in the cloud using the SAM CLI

Documentation Copy Section

- SAM Developer Guide
- SAM template specification
- SAM connectors
- SAM policy templates