Cloudformation nested stack outputs in yaml

Question

In my nested stacks I need to use output values and AWS::CloudFormation::Stack returns values as

Fn::GetAtt Outputs.NestedStackOutputName

But yaml doesn't allow me to use

!GetAtt MyResourceName.Outputs.MyOutputName

as it tries to split them into 3 pieces instead of the 2 it requires.

I also tried using

Value: "Fn::GetAtt": [ "MyResourceName", "Outputs.MyOutputName" ] 

but then I get

mapping values are not allowed here
  in "<string>", line 21, column 24:
        Value: "Fn::GetAtt": [ "MyResourceName", "Outputs.MyOutputName" ]

So how am I supposed to use this? Do I really have to switch to json for this?

Answer 1

It worked for me using these 2 stacks:

root.yml :

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  MyNestedStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: https://s3.amazonaws.com/spg-test-bucket/cloudformation/nested.yml?versionId=HqlgDnuntMzkmK0398GPdJRUXMN_PMdn
  RootBucket:
    Type: AWS::S3::Bucket
    Properties:
      LoggingConfiguration:
        DestinationBucketName:
          Fn::GetAtt: [MyNestedStack, Outputs.NestedBucket]

nested.yml :

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  DataBucket:
    Type: AWS::S3::Bucket
    Properties:
      AccessControl: LogDeliveryWrite
Outputs:
  NestedBucket:
    Value:
      Ref: DataBucket

Answer 2

Your issue is due to a known bug in aws-cli 's custom YAML-parsing code that was added recently as part of the aws cloudformation deploy and aws cloudformation package commands.

The issue was fixed in version 1.11.37 of aws-cli . To fix the issue, you can do either of the following:

• Upgrade aws-cli to version 1.11.37 or greater.
• Use aws cloudformation [create|update]-stack to create/update your stack instead of aws cloudformation [package|deploy] , if you're not making use of local artifacts.