Painlessly create or update a CloudFormation stack in an idempotent way

Michael Wittig – 16 Mar 2017

When integrating CloudFormation into your CI/CD pipeline you are faced with the challenge of creating a CloudFormation stack on the first run of the pipeline, while you need to update the stack for all following pipeline runs. If you use the AWS CLI this is painful.

Pain

You may also have your code and template in the same repository. Therefore code changes without the template. But the AWS CLI threats an update without changes to a stack as an error which is not the behavior that you need in your pipeline.

cfn-create-or-update can create or update a CloudFormation stack. If no updates are to be performed, no error is thrown. cfn-create-or-update behaves exactly as the AWS CLI regarding input values, output will be different.

Installation

To install the CLI tool cfn-create-or-update, run:

npm install -g cfn-create-or-update

To create or update a stack, run:

cfn-create-or-update --stack-name test --template-body file://template.yml

The first time you run this command, a stack will be created. The second time an update will be performed but only if the template has changes.

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CLI parameters

cfn-create-or-update behaves exactly as the AWS CLI regarding input values. Supported parameters (as documented in the AWS CLI create-stack or update-stack):

cfn-create-or-update
--stack-name
--template-body
--template-url
--parameters
--capabilities
--resource-types
--role-arn
--stack-policy-body
--stack-policy-url
--notification-arns
--tags

Global parameters (as documented in the AWS CLI

--profile
--region

Only used during create, otherwise ignored (as documented in the AWS CLI create-stack):

--disable-rollback | --no-disable-rollback
--timeout-in-minutes
--on-failure

Only used during update, otherwise ignored (as documented in the AWS CLI update-stack):

--use-previous-template | --no-use-previous-template]
--stack-policy-during-update-body
--stack-policy-during-update-url

Additional parameter, to wait for create complete / update complete.

---wait

cfn-create-or-update is available on GitHub for free (MIT license).

Other solutions to this problem:

Michael Wittig

Michael Wittig

Consultant. Entrepreneur. Author. Focusing on Amazon Web Services (AWS) since 2013.

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