AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: >
  Powertools for AWS Lambda (Python) data masking example

Globals: # https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-specification-template-anatomy-globals.html
  Function:
    Timeout: 5
    Runtime: python3.11
    Tracing: Active
    Environment:
      Variables:
        POWERTOOLS_SERVICE_NAME: PowertoolsHelloWorld
        POWERTOOLS_LOG_LEVEL: INFO
        KMS_KEY_ARN: !GetAtt DataMaskingMasterKey.Arn

# In production, we recommend you split up the encrypt and decrypt for fine-grained security.
# For example, one function can act as the encryption proxy via HTTP requests, data pipeline, etc.,
# while only authorized personnel can call decrypt via a separate function.
Resources:
  DataMaskingEncryptFunctionExample:
    Type: AWS::Serverless::Function
    Properties:
      Handler: data_masking_function_example.lambda_handler
      CodeUri: ../src
      Description: Data Masking encryption function
      # Cryptographic operations demand more CPU. CPU is proportionally allocated based on memory size.
      # We recommend allocating a minimum of 1024MB of memory.
      MemorySize: 1024

  # DataMaskingDecryptFunctionExample:
  #   Type: AWS::Serverless::Function
  #   Properties:
  #     Handler: data_masking_function_decrypt.lambda_handler
  #     CodeUri: ../src
  #     Description: Data Masking decryption function
  #     MemorySize: 1024

  # KMS Key
  DataMaskingMasterKey:
    Type: "AWS::KMS::Key"
    Properties:
      Description: KMS Key for encryption and decryption using Powertools for AWS Lambda Data masking feature
      # KMS Key support both IAM Resource Policies and Key Policies
      # For more details: https://docs.aws.amazon.com/kms/latest/developerguide/key-policies.html
      KeyPolicy:
        Version: "2012-10-17"
        Id: data-masking-enc-dec
        Statement:
          # For security reasons, ensure your KMS Key has at least one administrator.
          # In this example, the root account is granted administrator permissions.
          # However, we recommended configuring specific IAM Roles for enhanced security in production.
          - Effect: Allow
            Principal:
              AWS: !Sub "arn:aws:iam::${AWS::AccountId}:root" # (1)!
            Action: "kms:*"
            Resource: "*"
          # We must grant Lambda's IAM Role access to the KMS Key
          - Effect: Allow
            Principal:
              AWS: !GetAtt DataMaskingEncryptFunctionExampleRole.Arn # (2)!
            Action:
              - kms:Decrypt # to decrypt encrypted data key
              - kms:GenerateDataKey # to create an unique and random data key for encryption
              # Encrypt permission is required only when using multiple keys
              - kms:Encrypt  # (3)!
            Resource: "*"