aws-cloudformation - 有没有办法解析 Amazon Cloudformation 中的 EMR MasterPublicDNS？

Question

有没有办法解析Cloudformation中的EMR MasterPublicDNS？我在 Cloudformation 中没有看到替换功能。

ip-100-112-10-21.aws.internal

致

100.112.10.21

Outputs:
  IPAddress:
    Description: IP address of the EMR clusters
    Value: !GetAtt
      - EMRCluster
      - MasterPublicDNS

can I reference the output value in same script?
I need to use the formatted IP to set resourcerecords- or do I have to use 
Type: AWS::Route53::RecordSetGroup
 ResourceRecords: !Join [".",
      [
        !Select [1, !Split ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select [2, !Split ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select [3, !Split ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select [0,
          !Split ['.', !Select [4, !Split ['-', !GetAtt EMRCluster.MasterPublicDNS]]]]
      ]
    ]

 gives error - Value of property ResourceRecords must be of type List of String
 or 
 ResourceRecords: !ref IPAddress.value

Answer 1

如果格式始终是这样，您可以组合 Split、Select 和 Join Cloudformation intrinsic functions实现它:

Outputs:
  IPAddress:
    Description: IP address of the EMR clusters
    Value: !Join ['.',
      [
        !Select: [1, !Split: ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select: [2, !Split: ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select: [3, !Split: ['-', !GetAtt EMRCluster.MasterPublicDNS]],
        !Select: [0,
          !Split: ['.', !Select: [4, !Split: ['-', !GetAtt EMRCluster.MasterPublicDNS]]]]
      ]
    ]

我知道这会让您感到畏缩，但这就是 Cloudformation 的发展方向。

或者，您可以写 Cloudformation macro为您做这件事。