以云形式输出列表

Question

我有一个参数：

  ClusterSubnets:
    Description: Subnets where cluster will reside.
                Typically private.  Use mutiples, each in a different AZ for HA.
    ConstraintDescription: comma separated list of valid Subnet IDs
    Type: List<AWS::EC2::Subnet::Id>

我正在尝试输出：

  ClusterSubnets:
    Description: Subnets used by cluster
    Value: !Ref ClusterSubnets
    Export:
      Name: !Sub "${AWS::StackName}-ClusterSubnets"

但是，我得到了以下错误：模板格式错误：每个Outputs成员的Value字段必须求值为字符串。

如何导出列表？

Answer 1

您需要将列表的元素连接到字符串中。尝试这样的事情：

ClusterSubnets:
    Description: Subnets used by cluster
    Value: !Join
        - ','
        - !Ref ClusterSubnets
    Export:
        Name: !Sub "${AWS::StackName}-ClusterSubnets"

这是相关的AWS文档。