account_b_region_a.yml

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AWSTemplateFormatVersion: 2010-09-09
Description: Automating cross-account backup of Amazon RDS Oracle databases with AWS Backup - Account B, Region A
Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label:
          default: "AWS Backup Configuration"
        Parameters:
          - pBackupIAMRoleName
          - pBackupVaultName
          - pAWSOrganizationID
          - pDestinationAWSRegion
          - pKeyAdminIdentity
   
    ParameterLabels:
      pBackupIAMRoleName:
        default: AWS Backup IAM Role
      pBackupVaultName:
        default: AWS Backup Vault Name
      pAWSOrganizationID:
        default: AWS Organization ID
      pDestinationAWSRegion:
        default: AWS Backup Destination Region
      pKeyAdminIdentity:
        default: IAM user, IAM role or account root that gets permissions to manage the AWS KMS key

Parameters:
  pBackupIAMRoleName:
    Type: String
    Description: A name for the IAM role, up to 64 characters in length.
  pBackupVaultName:
    Type: String
    Description: The name of a logical container where backups are stored. Backup vaults are identified by names that are unique to the account used to create them and the AWS Region where they are created.
  pAWSOrganizationID:
    Type: String
    Description: AWS Organizations ID
  pDestinationAWSRegion:
    Type: String
    Description: AWS Region for cross-region backups. Do not select the same region where this CloudFormation stack is being created.
    AllowedValues:
      - us-east-1
      - us-east-2
      - us-west-1
      - us-west-2
      - ap-south-1
      - ap-northeast-1
      - ap-northeast-2
      - ap-northeast-3
      - ap-southeast-1
      - ap-southeast-2
      - ca-central-1
      - eu-central-1
      - eu-west-1
      - eu-west-2
      - eu-west-3
      - eu-north-1
      - sa-east-1
  pKeyAdminIdentity:
    Type: String
    Description: 'The principal element of the KMS key administrator. For example, "root", "user/ExampleAdminUser" or "role/ExampleAdminRole"'

Resources:
# IAM Role for AWS Backup
  rAWSBackupIAMRole:
    Type: AWS::IAM::Role
    Properties:
      Description: Allows AWS Backup to call AWS services on your behalf
      AssumeRolePolicyDocument: |
          {
            "Version": "2012-10-17",
            "Statement": [
              {
                "Effect": "Allow",
                "Principal": {
                  "Service": "backup.amazonaws.com"
                },
                "Action": "sts:AssumeRole"
              }
            ]
          }
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSBackupServiceRolePolicyForBackup
      RoleName: !Ref pBackupIAMRoleName

  rIAMPolicyRDSServiceLinkedRole:
    Type: AWS::IAM::Policy
    Properties:
      PolicyName: service-role-rds
      Roles:
        - !Ref rAWSBackupIAMRole
      PolicyDocument: !Sub |
          {
              "Version": "2012-10-17",
              "Statement": [
                  {
                      "Effect": "Allow",
                      "Action": "iam:CreateServiceLinkedRole",
                      "Resource": "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/rds.amazonaws.com/AWSServiceRoleForRDS"
                  }
              ]
          }
# AWS KMS Key and AWS Backup Vault
# Note: Second policy statement is not supported through the web console, only through CloudFormation or API call.
  rKMSCMK:
    Type: AWS::KMS::Key
    Properties:
      EnableKeyRotation: true
      Description: KMS key for AWS Backup Vault
      KeyPolicy: !Sub |
          {
              "Version": "2012-10-17",
              "Id": "backup-vault-policy-${pBackupVaultName}",
              "Statement": [
                  {
                      "Sid": "Enable IAM User Permissions",
                      "Effect": "Allow",
                      "Principal": {
                          "AWS": "arn:aws:iam::${AWS::AccountId}:${pKeyAdminIdentity}"
                      },
                      "Action": [
                        "kms:PutKeyPolicy",
                        "kms:ScheduleKeyDeletion",
                        "kms:EnableKeyRotation",
                        "kms:DescribeKey",
                        "kms:CreateAlias",
                        "kms:DeleteAlias",
                        "kms:CreateGrant"
                      ],
                      "Resource": "*"
                  },
                  {
                      "Sid": "Allow access from AWS Organizations accounts to copy backups",
                      "Effect": "Allow",
                      "Principal": {
                          "AWS": "*"
                      },
                      "Action": [
                          "kms:CreateGrant",
                          "kms:Decrypt",
                          "kms:GenerateDataKey*",
                          "kms:DescribeKey"
                      ],
                      "Resource": "*",
                      "Condition": {
                          "StringEquals": {
                              "aws:PrincipalOrgID": "${pAWSOrganizationID}"
                          }
                      }
                  }
              ]
          }     

  rKMSCMKAlias:
    Type: AWS::KMS::Alias
    Properties:
      AliasName: !Sub "alias/cmk-${pBackupVaultName}"
      TargetKeyId: !Ref rKMSCMK

  rBackupVault:
    Type: AWS::Backup::BackupVault
    Properties:
      AccessPolicy: !Sub |
          {
              "Version": "2012-10-17",
              "Statement": [
                  {
                      "Sid": "Enable backup vault access",
                      "Effect": "Allow",
                      "Principal": "*",
                      "Action": "backup:CopyIntoBackupVault",
                      "Resource": "arn:aws:backup:${AWS::Region}:${AWS::AccountId}:backup-vault:${pBackupVaultName}",
                      "Condition": {
                          "StringEquals": {
                              "aws:PrincipalOrgID": "${pAWSOrganizationID}"
                          }
                      }
                  }
              ]
          }
      BackupVaultName: !Ref pBackupVaultName
      EncryptionKeyArn: !GetAtt rKMSCMK.Arn
# EventBridge and Lambda Rule for Cross-Region Backup Copies
  rLambdaIAMRole:
    Type: "AWS::IAM::Role"
    Properties:
      Path: "/"
      RoleName: AWSBackupRDSAuroraLambdaRole
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          -
            Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
            Action:
              - sts:AssumeRole
      Policies:
        - PolicyName: Cloudwatch-Backup-Policy
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - backup:StartCopyJob
                  - backup:DescribeRecoveryPoint
                Resource: '*'
              - Effect: Allow
                Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:PutLogEvents
                Resource:
                  - arn:aws:logs:*:*:*
        - PolicyName: LambdaPolicy-AssumeRole
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - iam:PassRole
                Resource: !GetAtt rAWSBackupIAMRole.Arn
      Description: "Allows Lambda functions to call AWS services on your behalf"

  rLambdaFunction:
    Type: AWS::Lambda::Function
    Properties:
      Description: Lambda Function that triggers an AWS Backup Vault Copy in a different region
      Environment: 
        Variables: 
          role_name: !GetAtt rAWSBackupIAMRole.Arn
          destination_region: !Ref pDestinationAWSRegion
      FunctionName: "AWSBackup-RDS-Aurora-Cross-Region-Backup-Copy"
      Handler: index.lambda_handler
      Code:
        ZipFile: |
          import json, boto3, os, logging, time, sys

          def lambda_handler(event, context):
              # Logging configuration
              logger = logging.getLogger()
              logger.setLevel(logging.INFO)
              logging.getLogger("boto3").setLevel(logging.WARNING)
              logging.getLogger("botocore").setLevel(logging.WARNING)
              logger.debug('Incoming Event') 
              logger.debug(event)

              # Function variables
              backup_vault_name = event['detail']['destinationBackupVaultArn'].split(':')[6]
              source_region = event['detail']['destinationBackupVaultArn'].split(':')[3]
              lifecycle_value = 'CalculatedLifecycle'
              logger.info('Backup source account: ' + event['account'])
              logger.info('Recovery Point ARN to be copied: ' + event['detail']['destinationRecoveryPointArn'])

              # Environment variables
              destination_region = os.environ.get('destination_region')
              logger.info('Sending backup to the following AWS Region: ' + destination_region)
              role_name = os.environ.get('role_name')
              
              # Boto3 client
              backup_connection = boto3.client('backup')
              
              # Boto3 call to retrieve recovery point retention/lifecycle value
              recovery_point = backup_connection.describe_recovery_point(
                  BackupVaultName = backup_vault_name,
                  RecoveryPointArn = event['detail']['destinationRecoveryPointArn']
                  )
              logger.debug('Recovery Point Information')    
              logger.debug(recovery_point)

              # If value is found, it will be passed to the start copy job boto3 call
              try:
                  if lifecycle_value in recovery_point:
                      response = backup_connection.start_copy_job(
                          RecoveryPointArn = event['detail']['destinationRecoveryPointArn'],
                          SourceBackupVaultName = backup_vault_name,
                          DestinationBackupVaultArn = event['detail']['destinationBackupVaultArn'].replace(source_region,destination_region),
                          IamRoleArn = role_name,
                          Lifecycle={
                          'DeleteAfterDays': int(recovery_point['Lifecycle']['DeleteAfterDays'])
                          }        
                      )        
              
                  # Else, value has not been defined and will not be defined in start copy job boto3 call
                  else:
                      response = backup_connection.start_copy_job(
                          RecoveryPointArn = event['detail']['destinationRecoveryPointArn'],
                          SourceBackupVaultName = backup_vault_name,
                          DestinationBackupVaultArn = event['detail']['destinationBackupVaultArn'].replace(source_region,destination_region),
                          IamRoleArn = role_name
                      )
              except Exception as e:
                  logger.error(str(e))
                  
              logger.info('AWS Backup Copy Job ID: ' + response['CopyJobId'])    
              return json.dumps(response, default=str)
      MemorySize: 128
      Role: !GetAtt rLambdaIAMRole.Arn
      ReservedConcurrentExecutions: 5
      Runtime: python3.8
      Timeout: 3
      TracingConfig: 
        Mode: "PassThrough"

  rLambdaPermission:
    Type: "AWS::Lambda::Permission"
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !GetAtt rLambdaFunction.Arn
      Principal: events.amazonaws.com
      SourceArn: !GetAtt rEventsRule.Arn

  rEventsEventBusPolicy:
    Type: "AWS::Events::EventBusPolicy"
    Properties:
      StatementId: "AWSBackupCopyCompleteEvent"
      Action: "events:PutEvents"
      Condition: 
        Key: "aws:PrincipalOrgID"
        Type: "StringEquals"
        Value: !Ref pAWSOrganizationID
      Principal: "*"

  rEventsRule:
    Type: "AWS::Events::Rule"
    Properties:
      Name: "AWSBackupCopyCompleteRule"
      Description: "EventBridge Rule for CopyCompleteJob event to trigger cross-region backup copy for RDS/Aurora resources"
      EventPattern: !Sub |
          {
            "source": ["aws.backup"],
            "account": [{
              "anything-but": "${AWS::AccountId}"
            }],
            "detail-type": ["Copy Job State Change"],
            "detail": {
              "state": ["COMPLETED"],
              "resourceType": ["RDS", "Aurora"]
            }
          }
      State: "ENABLED"
      Targets: 
      - 
        Arn: !GetAtt rLambdaFunction.Arn
        Id: "TargetFunctionV1"
      EventBusName: "default"