如何转义“ $ {}”在云形式“ 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<不能替换的href = http://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_variables.html rel = noreferrer>政策变量。

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：您可以逃避 $ {aws：username} 以便！Sub 在这里可以用吗？ 不幸的是，文档

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

实际上，您可以使用 $ {！}来转义 $字符。 。

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

因此您的资源应如下所示：

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。

要从字面上写一个美元符号和花括号（$ {}），在大括号后加上
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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