prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  CKV_AWS_157 False Positive on Aurora
  **Describe the issue**
  CKV_AWS_157 fails on Aurora instances even though the `MultiAZ` property is not applicable to Aurora
  
  **Examples**
  ```
  RDSinstance:
      Type: AWS::RDS::DBInstance
      Properties:
        DBClusterIdentifier: !Ref DBCluster
        DBInstanceClass: !Ref DbType
        DBInstanceIdentifier: !Sub ${AppName}-${EnvironmentName}
        DBParameterGroupName: !Ref DbParameterGroup
        DBSubnetGroupName: !Ref DBSubnetGroup
        Engine: aurora-mysql
        MonitoringInterval: "60"
        MonitoringRoleArn: !GetAtt RdsMonitoringRole.Arn
        PubliclyAccessible: 'false'
  ```
  
  **Version (please complete the following information):**
   - Checkov Version 2.2.270
  
  **Additional context**
  - AWS docs: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz
  
  <img width="1377" alt="Screenshot 2023-01-19 at 1 25 49 PM" src="https://user-images.githubusercontent.com/1328683/213552592-4736b84a-3926-44b2-9dad-196b68f28daa.png">
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py`
  Content:
  ```
  1 from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck
  2 from checkov.common.models.enums import CheckCategories
  3 
  4 
  5 class RDSMultiAZEnabled(BaseResourceValueCheck):
  6     def __init__(self):
  7         name = "Ensure that RDS instances have Multi-AZ enabled"
  8         id = "CKV_AWS_157"
  9         supported_resources = ['AWS::RDS::DBInstance']
  10         categories = [CheckCategories.NETWORKING]
  11         super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)
  12 
  13     def get_inspected_key(self):
  14         return 'Properties/MultiAZ'
  15 
  16 
  17 check = RDSMultiAZEnabled()
  18
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
  --- a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
  +++ b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
  @@ -1,5 +1,5 @@
  +from checkov.common.models.enums import CheckResult, CheckCategories
   from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck
  -from checkov.common.models.enums import CheckCategories
   
   
   class RDSMultiAZEnabled(BaseResourceValueCheck):
  @@ -10,6 +10,16 @@
           categories = [CheckCategories.NETWORKING]
           super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)
   
  +    def scan_resource_conf(self, conf):
  +        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set
  +        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz
  +        if 'Properties' in conf.keys():
  +            if 'Engine' in conf['Properties'].keys():
  +                if 'aurora' in conf['Properties']['Engine']:
  +                    return CheckResult.UNKNOWN
  +        # Database is not Aurora; Use base class implementation
  +        return super().scan_resource_conf(conf)
  +            
       def get_inspected_key(self):
           return 'Properties/MultiAZ'
  
verification_info: {"golden_diff": "diff --git a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n--- a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n+++ b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n@@ -1,5 +1,5 @@\n+from checkov.common.models.enums import CheckResult, CheckCategories\n from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\n-from checkov.common.models.enums import CheckCategories\n \n \n class RDSMultiAZEnabled(BaseResourceValueCheck):\n@@ -10,6 +10,16 @@\n         categories = [CheckCategories.NETWORKING]\n         super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n \n+    def scan_resource_conf(self, conf):\n+        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set\n+        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\n+        if 'Properties' in conf.keys():\n+            if 'Engine' in conf['Properties'].keys():\n+                if 'aurora' in conf['Properties']['Engine']:\n+                    return CheckResult.UNKNOWN\n+        # Database is not Aurora; Use base class implementation\n+        return super().scan_resource_conf(conf)\n+            \n     def get_inspected_key(self):\n         return 'Properties/MultiAZ'\n", "issue": "CKV_AWS_157 False Positive on Aurora\n**Describe the issue**\r\nCKV_AWS_157 fails on Aurora instances even though the `MultiAZ` property is not applicable to Aurora\r\n\r\n**Examples**\r\n```\r\nRDSinstance:\r\n    Type: AWS::RDS::DBInstance\r\n    Properties:\r\n      DBClusterIdentifier: !Ref DBCluster\r\n      DBInstanceClass: !Ref DbType\r\n      DBInstanceIdentifier: !Sub ${AppName}-${EnvironmentName}\r\n      DBParameterGroupName: !Ref DbParameterGroup\r\n      DBSubnetGroupName: !Ref DBSubnetGroup\r\n      Engine: aurora-mysql\r\n      MonitoringInterval: \"60\"\r\n      MonitoringRoleArn: !GetAtt RdsMonitoringRole.Arn\r\n      PubliclyAccessible: 'false'\r\n```\r\n\r\n**Version (please complete the following information):**\r\n - Checkov Version 2.2.270\r\n\r\n**Additional context**\r\n- AWS docs: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\r\n\r\n<img width=\"1377\" alt=\"Screenshot 2023-01-19 at 1 25 49 PM\" src=\"https://user-images.githubusercontent.com/1328683/213552592-4736b84a-3926-44b2-9dad-196b68f28daa.png\">\r\n\n", "before_files": [{"content": "from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\nfrom checkov.common.models.enums import CheckCategories\n\n\nclass RDSMultiAZEnabled(BaseResourceValueCheck):\n    def __init__(self):\n        name = \"Ensure that RDS instances have Multi-AZ enabled\"\n        id = \"CKV_AWS_157\"\n        supported_resources = ['AWS::RDS::DBInstance']\n        categories = [CheckCategories.NETWORKING]\n        super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n\n    def get_inspected_key(self):\n        return 'Properties/MultiAZ'\n\n\ncheck = RDSMultiAZEnabled()\n", "path": "checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py"}], "after_files": [{"content": "from checkov.common.models.enums import CheckResult, CheckCategories\nfrom checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\n\n\nclass RDSMultiAZEnabled(BaseResourceValueCheck):\n    def __init__(self):\n        name = \"Ensure that RDS instances have Multi-AZ enabled\"\n        id = \"CKV_AWS_157\"\n        supported_resources = ['AWS::RDS::DBInstance']\n        categories = [CheckCategories.NETWORKING]\n        super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n\n    def scan_resource_conf(self, conf):\n        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set\n        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\n        if 'Properties' in conf.keys():\n            if 'Engine' in conf['Properties'].keys():\n                if 'aurora' in conf['Properties']['Engine']:\n                    return CheckResult.UNKNOWN\n        # Database is not Aurora; Use base class implementation\n        return super().scan_resource_conf(conf)\n            \n    def get_inspected_key(self):\n        return 'Properties/MultiAZ'\n\n\ncheck = RDSMultiAZEnabled()\n", "path": "checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py"}]}