CODEWITHSUNDEEP
amazon-web-servicesaws-cloudformation
Justin
Justin

Reputation: 4843

Problem when using !Sub in TemplateURL creation

Trying to deploy a nested Cloudformation stack. Works fine if I hardcode the TemplateURL as follows -

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  MyStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: https://s3.eu-west-1.amazonaws.com/my-bucket/my-template.yml

but as soon as I start to do any string substitution within TemplateURL eg

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  MyStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: !Sub "https://s3.#{AWS::Region}.amazonaws.com/my-bucket/my-template.yml"

then on deployment I get -

AWS::CloudFormation::Stack | CREATE_FAILED | TemplateURL must be an Amazon S3 URL.

I have tried different flavours of !Sub and Fn::Sub, and with using custom defined variables rather than AWS::Region, but always the same result :-/

What am I doing wrong here ?? TIA.

Upvotes: 1

Views: 1035

Answers (1)

MaiKaY
MaiKaY

Reputation: 4482

You should use ${AWS::Region} instead of #{AWS::Region} (dollar sign instead of hashtag)

A string with variables that AWS CloudFormation substitutes with their associated values at runtime. Write variables as ${MyVarName} [...]

Source: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-sub.html

Upvotes: 5

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