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AWS::Serverless transform

The `AWS::Serverless` transform, which is a macro hosted by AWS CloudFormation, takes an entire template written in the AWS Serverless Application Model (AWS SAM) syntax and transforms and expands it into a compliant AWS CloudFormation template. For more information about serverless applications and AWS SAM, see Deploying Lambda\-based applications in the *AWS Lambda Developer Guide* and AWS SAM resource and property reference in the AWS Serverless Application Model Developer Guide.

Deploying Lambda-based applications

AWS SAM resource and property reference

In the following example, the template uses AWS SAM syntax to simplify the declaration of a Lambda function and its execution role.

Transform: AWS::Serverless-2016-10-31
Resources:
  MyServerlessFunctionLogicalID:
    Type: AWS::Serverless::Function
    Properties:
      Handler: index.handler
      Runtime: nodejs8.10
      CodeUri: 's3://testBucket/mySourceCode.zip'

When creating a change set from the template, AWS CloudFormation expands the AWS SAM syntax, as defined by the transform. The processed template expands the `AWS::Serverless::Function` resource, declaring an AWS Lambda function and an execution role.

{
  "Resources": {
    "MyServerlessFunctionLogicalID": {
      "Type": "AWS::Lambda::Function",
      "Properties": {
        "Handler": "index.handler",
        "Code": {
          "S3Bucket": "testBucket",
          "S3Key": "mySourceCode.zip"
        },
        "Role": {
          "Fn::GetAtt": ["FunctionNameRole", "Arn"]
        },
        "Runtime": "nodejs8.10"
      }
    },
    "FunctionNameRole": {
      "Type": "AWS::IAM::Role",
      "Properties": {
        "ManagedPolicyArns": ["arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"],
        "AssumeRolePolicyDocument": {
          "Version": "2012-10-17",
          "Statement": [{
            "Action": ["sts:AssumeRole"],
            "Effect": "Allow",
            "Principal": {
              "Service": ["lambda.amazonaws.com"]
            }
          }]
        }
      }
    }
  }
}

Syntax

The value for the transform declaration must be a literal string. You cannot use a parameter or function to specify a transform value. The following snippet is an example of a transform declaration:

JSON

"Transform" : "AWS::Serverless-2016-10-31"

YAML

Transform: "AWS::Serverless-2016-10-31"