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# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0
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AWSTemplateFormatVersion: 2010-09-09
Description:
  This template creates AWS Control Tower Account SSM Parameters. - 'common_prerequisites' solution in the repo,
  https://github.com/aws-samples/aws-security-reference-architecture-examples (sra-1ssgnse2h)
Metadata:
  SRA:
    Version: 1.0
    Order: 4
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label:
          default: General Properties
        Parameters:
          - pSRASolutionTagKey
          - pSRASolutionName
          - pSRAStagingS3BucketName
      - Label:
          default: Management Account Parameters - Lambda Function Properties
        Parameters:
          - pManagementAccountParametersLambdaRoleName
          - pManagementAccountParametersLambdaFunctionName
      - Label:
          default: General Lambda Function Properties
        Parameters:
          - pCreateLambdaLogGroup
          - pLambdaLogGroupRetention
          - pLambdaLogGroupKmsKey
          - pLambdaLogLevel
    ParameterLabels:
      pCreateLambdaLogGroup:
        default: Create Lambda Log Group
      pLambdaLogGroupKmsKey:
        default: (Optional) Lambda Logs KMS Key
      pLambdaLogGroupRetention:
        default: Lambda Log Group Retention
      pLambdaLogLevel:
        default: Lambda Log Level
      pManagementAccountParametersLambdaFunctionName:
        default: Management Account Parameters - Lambda Function Name
      pManagementAccountParametersLambdaRoleName:
        default: Management Account Parameters - Lambda Role Name
      pSRASolutionName:
        default: SRA Solution Name
      pSRASolutionTagKey:
        default: SRA Solution Tag Key
      pSRAStagingS3BucketName:
        default: (Optional) SRA Staging S3 Bucket Name

Parameters:
  pCreateLambdaLogGroup:
    AllowedValues: ['true', 'false']
    Default: 'false'
    Description:
      Indicates whether a CloudWatch Log Group should be explicitly created for the Lambda function, to allow for setting a Log Retention and/or KMS
      Key for encryption.
    Type: String
  pLambdaLogGroupKmsKey:
    AllowedPattern: '^$|^arn:(aws[a-zA-Z-]*){1}:kms:[a-z0-9-]+:\d{12}:key\/[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$'
    ConstraintDescription: 'Key ARN example:  arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab'
    Default: ''
    Description:
      (Optional) KMS Key ARN to use for encrypting the Lambda logs data. If empty, encryption is enabled with CloudWatch Logs managing the server-side
      encryption keys.
    Type: String
  pLambdaLogGroupRetention:
    AllowedValues: [1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, 3653]
    Default: 14
    Description: Specifies the number of days you want to retain log events
    Type: String
  pLambdaLogLevel:
    AllowedValues: [INFO, ERROR, DEBUG]
    Default: INFO
    Description: Lambda Function Logging Level
    Type: String
  pManagementAccountParametersLambdaFunctionName:
    AllowedPattern: '^[\w-]{1,64}$'
    ConstraintDescription: Max 64 alphanumeric characters. Also special characters supported [_, -]
    Default: sra-management-account-parameters
    Description: Lambda function name for creating Control Tower account SSM parameters.
    Type: String
  pManagementAccountParametersLambdaRoleName:
    AllowedPattern: '^[\w+=,.@-]{1,64}$'
    ConstraintDescription: Max 64 alphanumeric characters. Also special characters supported [+, =, ., @, -].
    Default: sra-management-account-parameters-lambda
    Description: Lambda execution role for creating Control Tower account SSM parameters.
    Type: String
  pSRASolutionName:
    AllowedValues: [sra-common-prerequisites]
    Default: sra-common-prerequisites
    Description: The SRA solution name. The default value is the folder name of the solution
    Type: String
  pSRASolutionTagKey:
    AllowedValues: [sra-solution]
    Default: sra-solution
    Description: The SRA solution tag key applied to all resources created by the solution that support tagging. The value is the pSRASolutionName.
    Type: String
  pSRAStagingS3BucketName:
    AllowedPattern: '^$|^[0-9a-zA-Z]+([0-9a-zA-Z-]*[0-9a-zA-Z])*$'
    ConstraintDescription:
      S3 bucket name can include numbers, lowercase letters, uppercase letters, and hyphens (-). It cannot start or end with a hyphen (-).
    Default: ''
    Description:
      (Optional) SRA Staging S3 bucket name for the artifacts relevant to solution. (e.g., lambda zips, CloudFormation templates). If empty, the SRA
      Staging S3 bucket name will be resolved from the SSM Parameter '/sra/staging-s3-bucket-name'.
    Type: String

Conditions:
  cCreateLambdaLogGroup: !Equals [!Ref pCreateLambdaLogGroup, 'true']
  cUseKmsKey: !Not [!Equals [!Ref pLambdaLogGroupKmsKey, '']]
  cUseSRAStagingS3BucketNameSSMParameter: !Equals [!Ref pSRAStagingS3BucketName, '']
  cUseGraviton: !Or
    - !Equals [!Ref 'AWS::Region', ap-northeast-1]
    - !Equals [!Ref 'AWS::Region', ap-south-1]
    - !Equals [!Ref 'AWS::Region', ap-southeast-1]
    - !Equals [!Ref 'AWS::Region', ap-southeast-2]
    - !Equals [!Ref 'AWS::Region', eu-central-1]
    - !Equals [!Ref 'AWS::Region', eu-west-1]
    - !Equals [!Ref 'AWS::Region', eu-west-2]
    - !Equals [!Ref 'AWS::Region', us-east-1]
    - !Equals [!Ref 'AWS::Region', us-east-2]
    - !Equals [!Ref 'AWS::Region', us-west-2]

Resources:
  rManagementAccountParametersLambdaCustomResource:
    Type: Custom::LambdaCustomResource
    Version: '1.0'
    Properties:
      ServiceToken: !GetAtt rManagementAccountParametersLambdaFunction.Arn
      TAG_KEY: !Ref pSRASolutionTagKey
      TAG_VALUE: !Ref pSRASolutionName

  rManagementAccountParametersLambdaFunction:
    Metadata:
      cfn_nag:
        rules_to_suppress:
          - id: W58
            reason: Lambda role provides access to CloudWatch Logs
          - id: W89
            reason: Lambda does not need to communicate with VPC resources.
          - id: W92
            reason: Lambda does not need reserved concurrent executions.
      checkov:
        skip:
          - id: CKV_AWS_115
            comment: Lambda does not need reserved concurrent executions.
          - id: CKV_AWS_116
            comment: DLQ not needed, as Lambda function only triggered by CloudFormation events.
          - id: CKV_AWS_117
            comment: Lambda does not need to communicate with VPC resources.
          - id: CKV_AWS_173
            comment: Environment variables are not sensitive
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: !Ref pManagementAccountParametersLambdaFunctionName
      Description: Creates Control Tower account SSM Parameters in the Management Account
      Architectures: !If
        - cUseGraviton
        - [arm64]
        - !Ref AWS::NoValue
      Handler: app.lambda_handler
      Role: !GetAtt rManagementAccountParametersLambdaRole.Arn
      Runtime: python3.9
      Timeout: 300
      Code:
        S3Bucket: !If
          - cUseSRAStagingS3BucketNameSSMParameter
          - '{{resolve:ssm:/sra/staging-s3-bucket-name}}'
          - !Ref pSRAStagingS3BucketName
        S3Key: !Sub ${pSRASolutionName}/lambda_code/${pSRASolutionName}.zip
      Environment:
        Variables:
          LOG_LEVEL: !Ref pLambdaLogLevel
      Tags:
        - Key: !Ref pSRASolutionTagKey
          Value: !Ref pSRASolutionName

  rManagementAccountParametersLambdaLogGroup:
    Condition: cCreateLambdaLogGroup
    DeletionPolicy: Retain
    Type: AWS::Logs::LogGroup
    UpdateReplacePolicy: Retain
    Properties:
      LogGroupName: !Sub /aws/lambda/${pManagementAccountParametersLambdaFunctionName}
      KmsKeyId: !If
        - cUseKmsKey
        - !Ref pLambdaLogGroupKmsKey
        - !Ref AWS::NoValue
      RetentionInDays: !Ref pLambdaLogGroupRetention

  rManagementAccountParametersLambdaRole:
    Type: AWS::IAM::Role
    Metadata:
      cfn_nag:
        rules_to_suppress:
          - id: W11
            reason: Allow * in resource when required
          - id: W28
            reason: The role name is defined to identify automation resources
    Properties:
      RoleName: !Ref pManagementAccountParametersLambdaRoleName
      Description: !Sub Role for '${pManagementAccountParametersLambdaRoleName}' Lambda function
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Action: sts:AssumeRole
            Principal:
              Service:
                - lambda.amazonaws.com
      Tags:
        - Key: !Ref pSRASolutionTagKey
          Value: !Ref pSRASolutionName
      Policies:
        - PolicyName: ssm-account-parameter-creator
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Sid: STSOrganizationRead
                Effect: Allow
                Action:
                  - organizations:DescribeOrganization
                  - organizations:ListAccounts
                  - organizations:ListRoots
                Resource: '*'
              - Sid: CloudFormationRead
                Effect: Allow
                Action:
                  - cloudformation:DescribeStackSet
                  - cloudformation:ListStackInstances
                Resource: '*'
              - Sid: SSMParameterRead
                Effect: Allow
                Action: ssm:DescribeParameters
                Resource: '*'
              - Sid: SSMParameterReadValues
                Effect: Allow
                Action: ssm:GetParameters
                Resource: !Sub arn:${AWS::Partition}:ssm:*:${AWS::AccountId}:parameter/sra/*
              - Sid: SSMParameterWrite
                Effect: Allow
                Action:
                  - ssm:AddTagsToResource
                  - ssm:DeleteParameters
                  - ssm:PutParameter
                Resource: !Sub arn:${AWS::Partition}:ssm:*:${AWS::AccountId}:parameter/sra/*
              - Sid: TagsRead
                Effect: Allow
                Action: tag:GetResources
                Resource: '*'
        - PolicyName: CloudWatchLogGroup
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Sid: CloudWatchLogs
                Effect: Allow
                Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:PutLogEvents
                Resource: !Sub arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/${pManagementAccountParametersLambdaFunctionName}:log-stream:*

Outputs:
  oAuditAccountId:
    Description: Audit Account ID
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.AuditAccountId
  oCustomerControlTowerRegions:
    Description: Customer Control Tower Regions
    Value: !Join [',', !GetAtt rManagementAccountParametersLambdaCustomResource.CustomerControlTowerRegions]
  oCustomerControlTowerRegionsWithoutHomeRegion:
    Description: Customer Control Tower Regions without Home Region
    Value: !Join [',', !GetAtt rManagementAccountParametersLambdaCustomResource.CustomerControlTowerRegionsWithoutHomeRegion]
  oEnabledRegions:
    Description: Enabled Regions
    Value: !Join [',', !GetAtt rManagementAccountParametersLambdaCustomResource.EnabledRegions]
  oEnabledRegionsWithoutHomeRegion:
    Description: Enabled Regions without Home Region
    Value: !Join [',', !GetAtt rManagementAccountParametersLambdaCustomResource.EnabledRegionsWithoutHomeRegion]
  oHomeRegion:
    Description: Control Tower Home Region
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.HomeRegion
  oLogArchiveAccountId:
    Description: Log Archive Account ID
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.LogArchiveAccountId
  oManagementAccountId:
    Description: Management Account ID
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.ManagementAccountId
  oOrganizationId:
    Description: Organization ID
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.OrganizationId
  oRootOrganizationalUnitId:
    Description: Root Organizational Unit ID
    Value: !GetAtt rManagementAccountParametersLambdaCustomResource.RootOrganizationalUnitId
  oManagementAccountParametersLambdaFunctionArn:
    Description: Management Account Parameters Lambda Function ARN
    Value: !GetAtt rManagementAccountParametersLambdaFunction.Arn
  oManagementAccountParametersLambdaLogGroupArn:
    Condition: cCreateLambdaLogGroup
    Description: Management Account Parameters Lambda Log Group ARN
    Value: !GetAtt rManagementAccountParametersLambdaLogGroup.Arn
  oManagementAccountParametersLambdaRoleArn:
    Description: Management Account Parameters Lambda Role ARN
    Value: !GetAtt rManagementAccountParametersLambdaRole.Arn