cli: cdk migrate outputs an incorrect template for Lambda environment variables

[ymhiroki]

Describe the bug

I ran cdk migrate command with the CFn template below, which copied from the blog post.

AWSTemplateFormatVersion: "2010-09-09"
Description: AWS CDK Migrate Demo Template
Parameters:
  FunctionResponse:
    Description: Response message from the Lambda function
    Type: String
    Default: Hello World
  BucketTag:
    Description: The tag value of the S3 bucket
    Type: String
    Default: ChangeMe
Resources:
  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
  HelloWorldFunction:
    Type: AWS::Lambda::Function
    Properties:
      Role: !GetAtt LambdaExecutionRole.Arn
      Code:
        ZipFile: |
          import os
          def lambda_handler(event, context):
            function_response = os.getenv('FUNCTION_RESPONSE')
            return {
              "statusCode": 200,
              "body": function_response
            }
      Handler: index.lambda_handler
      Runtime: python3.11
      Environment:
        Variables:
          FUNCTION_RESPONSE: !Ref FunctionResponse
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      PublicAccessBlockConfiguration:
        BlockPublicAcls: true
        BlockPublicPolicy: true
        IgnorePublicAcls: true
        RestrictPublicBuckets: true
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
      Tags:
        - Key: Application
          Value: Git-Sync-Demo
        - Key: DynamicTag
          Value: !Ref BucketTag
Outputs:
  S3BucketName:
    Description: The name of the S3 bucket
    Value: !Ref S3Bucket
    Export:
      Name: !Sub ${AWS::StackName}-S3BucketName

The command generates the typescript code below for the Lambda function.

    const helloWorldFunction = new lambda.CfnFunction(this, 'HelloWorldFunction', {
      role: lambdaExecutionRole.attrArn,
      code: {
        zipFile: 'import os\ndef lambda_handler(event, context):\n  function_response = os.getenv(\'FUNCTION_RESPONSE\')\n  return {\n    \"statusCode\": 200,\n    \"body\": function_response\n  }\n',
      },
      handler: 'index.lambda_handler',
      runtime: 'python3.11',
      environment: {
        variables: {
          functionResponse: props.functionResponse!,
        },
      },
    });

variables should contain FUNCTION_RESPONSE, however, it's actually functionResponse.

Expected Behavior

Lambda environment variables must contain FUNCTION_RESPONSE like the code below.

    const helloWorldFunction = new lambda.CfnFunction(this, 'HelloWorldFunction', {
      role: lambdaExecutionRole.attrArn,
      code: {
        zipFile: 'import os\ndef lambda_handler(event, context):\n  function_response = os.getenv(\'FUNCTION_RESPONSE\')\n  return {\n    \"statusCode\": 200,\n    \"body\": function_response\n  }\n',
      },
      handler: 'index.lambda_handler',
      runtime: 'python3.11',
      environment: {
        variables: {
          FUNCTION_RESPONSE: props.functionResponse!,
        },
      },
    });

Current Behavior

cdk migrate command generates an incorrect template for Lambda environment variables.
The function doesn't work well since it can't read environment variables.

    const helloWorldFunction = new lambda.CfnFunction(this, 'HelloWorldFunction', {
      role: lambdaExecutionRole.attrArn,
      code: {
        zipFile: 'import os\ndef lambda_handler(event, context):\n  function_response = os.getenv(\'FUNCTION_RESPONSE\')\n  return {\n    \"statusCode\": 200,\n    \"body\": function_response\n  }\n',
      },
      handler: 'index.lambda_handler',
      runtime: 'python3.11',
      environment: {
        variables: {
          functionResponse: props.functionResponse!,
        },
      },
    });

Reproduction Steps

Run cdk migrate --stack-name sample-stack --language typescript --from-path ./demo-template.yaml

with demo-template.yaml:

AWSTemplateFormatVersion: "2010-09-09"
Description: AWS CDK Migrate Demo Template
Parameters:
  FunctionResponse:
    Description: Response message from the Lambda function
    Type: String
    Default: Hello World
  BucketTag:
    Description: The tag value of the S3 bucket
    Type: String
    Default: ChangeMe
Resources:
  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
  HelloWorldFunction:
    Type: AWS::Lambda::Function
    Properties:
      Role: !GetAtt LambdaExecutionRole.Arn
      Code:
        ZipFile: |
          import os
          def lambda_handler(event, context):
            function_response = os.getenv('FUNCTION_RESPONSE')
            return {
              "statusCode": 200,
              "body": function_response
            }
      Handler: index.lambda_handler
      Runtime: python3.11
      Environment:
        Variables:
          FUNCTION_RESPONSE: !Ref FunctionResponse
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      PublicAccessBlockConfiguration:
        BlockPublicAcls: true
        BlockPublicPolicy: true
        IgnorePublicAcls: true
        RestrictPublicBuckets: true
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
      Tags:
        - Key: Application
          Value: Git-Sync-Demo
        - Key: DynamicTag
          Value: !Ref BucketTag
Outputs:
  S3BucketName:
    Description: The name of the S3 bucket
    Value: !Ref S3Bucket
    Export:
      Name: !Sub ${AWS::StackName}-S3BucketName

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.126.0 (build fb74c41)

Framework Version

No response

Node.js Version

v20.10.0

OS

macOS Sonoma 14.3 (23D56)

Language

TypeScript

Language Version

No response

Other information

No response

[tim-finnigan]

Thanks for reporting this issue, this does appear to be a bug with the environment variable getting converted to camel case.

[TheRealAmazonKendra]

Duplicate of #29027

[TheRealAmazonKendra]

This fix for this was released in v2.132.

[github-actions]

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