How to escape "${}" in cloudformations "Fn::Sub"

Question

I want this resource to work with the !Sub (or Fn::Sub) intrinsic function

Resource: !Sub 'arn:aws:iam::${AWS::AccountId}:user/${aws:username}'

The aws:username is a pollicy variable that mustn't be replaced.

One solution would be to use Fn::Join instead and write a bit more boilerplate code.

Better: Can you escape the ${aws:username} so that !Sub will work here? Unfortunately, the documentation does not mention anything about escaping.

Answer 1

您实际上可以使用“$ {！}”转义“$”字符。

所以你的资源看起来像这样：

Resource: !Sub 'arn:aws:iam::${AWS::AccountId}:user/${!aws:username}'

在字符串参数部分的docs中提到。

  

按字面意思写一个美元符号和花括号（$ {}），添加一个   打开花括号后的感叹号（！），例如$ {！Literal}。   AWS CloudFormation将此文本解析为$ {Literal}。