Share Values upstream in a nested cloudformation stack possible?

Question

Is there some way to pass on Values form a child stack to a parent stack? All I found was to pass values down, but never up, that would unfortunately not correspond with my stack architecture. I could use cross-referencing with eXport/Import but would rather keep the nested stack if possible.

Wouldn't that create some sort of circular reference between your stacks? Each one will have to be deployed for the other one to import the value — yorodm
I Tried @aerioeus way but not worked! Then i changed !Ref by !GetAtt its worked! !GetAtt [SomeChildStack, Outputs.MyOutput] — デゥック

maafk maafk · Accepted Answer · 2018-09-08T00:19:43

You can definitely gather outputed values from a child stack and use them in the parent stack.

For example:

# parent stack
AWSTemplateFormatVersion: 2010-09-09
Resources:
  SomeChildStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      Parameters:
        AWS CloudFormation Stack Parameters
      TemplateURL: !Ref SomeTemplateUrl

  SomeOtherResource:
    Type: AWS::AnyOther::Resources
    Properties:
      SomeProperty: !Ref SomeChildStack.Outputs.MyOutput

And in SomeChildStack:

# The template used for SomeChildStack
AWSTemplateFormatVersion: 2010-09-09
Resources:
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      AccessControl: PublicRead
      LoggingConfiguration:
        DestinationBucketName: !Ref 'LoggingBucket'
        LogFilePrefix: testing-logs
Outputs:
  MyOutput:
    Value: !Ref 'S3Bucket'
    Description: Name of the sample Amazon S3 bucket.

The tricky thing to remember is adding the Outputs when referencing the AWS::CloudFormation::Stack.

Note that this will make SomeOtherResource depend on SomeChildStack, so SomeOtherResource won't be created until SomeChildStack has been created.

Share Values upstream in a nested cloudformation stack possible?

1 Answers