CloudFormation Fn::Transform 操作：下层 -> 语法错误

如何解决CloudFormation Fn::Transform 操作：下层 -> 语法错误

我正在尝试使用云形成创建 AWS S3 存储桶。

S3 存储桶名称需要小写，但我想使用参数来复合该名称。这个参数是大写的。

我开辟了一条道路。

我读过这个。

https://github.com/awslabs/aws-cloudformation-templates/tree/master/aws/services/CloudFormation/MacrosExamples/StringFunctions

这是我的代码：

Parameters:

# Global
  ServiceName:
    Type: String
    Description: 'Service Name'
    Default: content-input
   
  Environment:
    Type: String
    Description: 'Environment Name'

Resources:
  S3Bucket: 
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Join ['-',[ 
        content-input,'Fn::Transform':
          - Name: 'String'
          Parameters: 
            InputString: !Ref Environment
            Operation: Lower
      ]]

但我收到此错误。

while parsing a flow node
expected the node content,but found '-'
  in "<unicode string>",line 157,column 11:
              - Name: 'String'

我尝试了其他语法引用 here

Parameters:

# Global
  ServiceName:
    Type: String
    Description: 'Service Name'
    Default: content-input
   
  Environment:
    Type: String
    Description: 'Environment Name'

Resources:
  S3Bucket: 
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Join ['-','Fn::Transform':
          Name: 'String'
          Parameters: 
            InputString: !Ref Environment
            Operation: Lower
      ]]

但我明白了：

while parsing a flow sequence
  in "<unicode string>",line 154,column 7:
          [
          ^
expected ',' or ']',but got ':'
  in "<unicode string>",column 15:
              Name: 'String'
                  ^

当然，这项工作完美。

Parameters:

# Global
  ServiceName:
    Type: String
    Description: 'Service Name'
    Default: content-input
   
  Environment:
    Type: String
    Description: 'Environment Name'

Resources:
  S3Bucket: 
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Join ['-',mytext
      ]]

正确的语法是怎样的？

解决方法

要使语法正确，需要注意的重要一点是在使用多个内在函数时将 Json 与 Yaml 一起使用。下面更新了语法。对于环境值 DEV，这将创建一个名称为 content-input-dev

的存储桶

AWSTemplateFormatVersion: "2010-09-09"
Parameters:
  ServiceName:
    Type: String
    Description: "Service Name"
    Default: content-input
  Environment:
    Type: String
    Description: "Environment Name"
Resources:
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName:
        !Join [
          "-",[
            !Ref ServiceName,{
              "Fn::Transform":
                {
                  "Name": "String","Parameters":
                    { "InputString": !Ref Environment,"Operation": "Lower" },},],]