如何转义“${}"在 cloudformations “Fn::Sub"中 [英] How to escape "${}" in cloudformations "Fn::Sub"

问题描述

我希望此资源与 !Sub(或 Fn::Sub)内在函数一起使用

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

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

aws:username 是一个 政策不能被替换的变量.

一种解决方案是改用 Fn::Join 并编写更多样板代码.

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

更好:您可以转义 ${aws:username} 以便 !Sub 在这里工作吗?不幸的是，文档没有提到任何关于逃避的事情.

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

推荐答案

您实际上可以使用 ${!} 转义 $ 字符.

You actually can escape $ characters with ${!}.

所以你的资源看起来像这样:

So your resource would look like this:

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

文档 在字符串参数部分下.

It is mentioned in the docs under the string parameter section.

要从字面上写一个美元符号和花括号 (${})，请添加一个左花括号后的感叹号 (!)，例如 ${!Literal}.AWS CloudFormation 将此文本解析为 ${Literal}.

To write a dollar sign and curly braces (${}) literally, add an exclamation point (!) after the open curly brace, such as ${!Literal}. AWS CloudFormation resolves this text as ${Literal}.

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