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Putnik
Asked: 2017-08-06 23:30:27 +0800 CST

CloudFormation template: how to use Sub and GetAtt at the same time in short form?

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I'm using yaml. So, we can use either:

!GetAtt [ WebServer, AvailabilityZone ]
!GetAtt WebServer.AvailabilityZone

Also, we can use:

!Sub 'sometext-${AWS::StackName}'

how can I use GetAtt output instead of ${AWS::StackName}, preferably using the second form of GetAtt? I do know how to use Join but I'd like to stay with Sub.

amazon-web-services

1 Answers

  1. Best Answer

    Simply remove !GetAtt and reference the desired variable. In the following code EIP.AllocationId normally returned via !GetAtt. 

    !Sub |
#!/bin/bash
export INSTANCEID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
aws ec2 associate-address --instance-id $INSTANCEID --allow-reassociation --allocation-id ${EIP.AllocationId} --region ${AWS::Region}
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