Cloudformation WaitCondition Update Macro

The Cloudformation resources AWS::Cloudformation::WaitCondition and AWS::Cloudformation::WaitConditionHandle cannot currently be updated or recreated. To wait for resource signaling during a stack update a new WaitCondition resource needs to be created. This macro will create new WaitCondition resources based on changes to specified parameters.

Testing

# Unit Test
python3 -m unittest

Build

Note

S3 Bucket must already exist

Set any required AWS CLI env variables. http://docs.aws.amazon.com/cli/latest/userguide/cli-environment.html

./build.sh

aws cloudformation package \
  --template deploy-macro.yaml \
  --s3-bucket <YOUR S3 BUCKET> \
  --output-template-file packaged-deploy-macro.yaml

Deploy

aws cloudformation deploy \
  --template-file packaged-deploy-macro.yaml \
  --stack-name cloudformation-macro-WaitConditionUpdate \
  --capabilities CAPABILITY_IAM

How to Use

Your template must have contain the parameter WaitConditionUpdateParameters and Transform. When the parameters of WaitConditionUpdateParameters change the logical ids of all WaitCondition resources will be renamed.

Transform: ['WaitConditionUpdate']
Parameters:
  WaitConditionUpdateParameters:
    Description: Used by the WaitConditionUpdate transform macro to determine which
      parameter values will be used for naming any WaitCondition resources.  The
      parameters must only be those which will trigger a recreation of the signaling
      resource when changed.
    Type: CommaDelimitedList
    Default: "PutDefaultsHere"

Example

Use a WaitCondition to get a signal when tasks are healthy in a ECS Service

example-ecs-service.yaml