CodeCommitレポジトリ作成時に指定のブランチに特定のファイルを作るカスタムリソースを作成してみた

AWSTemplateFormatVersion: '2010-09-09'
Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
    - Label:
        default: "General Configuration"
      Parameters:
        - RepositoryName
        - BranchName
        - FilePath
        - FileContent
Parameters:
  RepositoryName:
    Type: String
    Description: "Enter the name of the repository"
    Default: "test-repo"
  BranchName:
    Type: String
    Description: "Enter the name of the branch where you want to store README.md"
    Default: "main"
  FilePath:
    Type: String
    Description: "Enter the name of the file"
    Default: "README.md"
  FileContent:
    Type: String
    Description: "Enter the contents of the README.md"
    Default: "Hello, World"

Resources:
#################################
# CodeCommit Repository
#################################
  Repository:
    Type: AWS::CodeCommit::Repository
    Properties:
      RepositoryName: !Ref RepositoryName

#################################
# Custom Resource
#################################
  PutReadMeRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      Path: /
      ManagedPolicyArns:
        - "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
        - "arn:aws:iam::aws:policy/AWSCodeCommitPowerUser"

  PutReadMeLog:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: !Sub "/aws/lambda/${RepositoryName}-${BranchName}-put-readme"

  PutReadMeFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: !Sub "${RepositoryName}-${BranchName}-put-readme"
      Code:
        ZipFile: |
          import json
          import boto3
          import cfnresponse

          def handler(event, context):
              try:
                  repository = event['ResourceProperties']['RepositoryName']
                  branch = event['ResourceProperties']['BranchName']
                  content = event['ResourceProperties']['FileContent'].encode()
                  path = event['ResourceProperties']['FilePath']

                  if event['RequestType'] == 'Create':
                      codecommit = boto3.client('codecommit')
                      response = codecommit.put_file(
                          repositoryName=repository,
                          branchName=branch,
                          fileContent=content,
                          filePath=path,
                          commitMessage='Initial Commit',
                          name='Your Lambda Helper'
                      )
                      cfnresponse.send(event, context, cfnresponse.SUCCESS, response)
                  if event['RequestType'] == 'Delete':
                      cfnresponse.send(event, context, cfnresponse.SUCCESS, {'Response': 'Success'})
                  if event['RequestType'] == 'Update':
                      cfnresponse.send(event, context, cfnresponse.SUCCESS, {'Response': 'Success'})
              except Exception as e:
                  print(e)
                  cfnresponse.send(event, context, cfnresponse.FAILED, {})
      Handler: index.handler
      MemorySize: 128
      Role: !GetAtt PutReadMeRole.Arn
      Runtime: "python3.9"
      Timeout: 60
      Tags:
        - Key: "Name"
          Value: !Sub "${RepositoryName}-${BranchName}-put-readme"
    DependsOn: PutReadMeLog

  PutReadMe:
    Type: Custom::CodeCommitPutReadMe
    Properties:
      ServiceToken: !GetAtt PutReadMeFunction.Arn
      RepositoryName: !GetAtt Repository.Name
      BranchName: !Ref BranchName
      FileContent: !Ref FileContent
      FilePath: !Ref FilePath