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My CF is having Step Function state machine configuration which definition is placed at some S3 location.

Now if there is any change in the definition, i.e. change only in the S3 file, in this case updating CF is failing.

Solution I tried I Have declared a parameter in my CF(say buildVersion) and every change in the S3 will lead to new build version and this build version I am sending though parameters

aws cloudformation --region "xyz" update-stack --stack-name "my stack name" --timeout-in-minutes 15 --template-body "CF file path" --parameters "parameter-file path"

This is how my parameter file look like, So before calling this command I am updating the parameter file with this buildVersion parameter.

[
   {"ParameterKey":"EnvironmentName", "ParameterValue":"dev"},
   {"ParameterKey":"BuildVersion", "ParameterValue":"0.0"}
]

But it is not solving the purpose and update command is failing, If I am doing the same thing with the AWS console i.e. updating parameter and click on update it is working fine.

Any suggestions will be highly appreciated.

Vicky
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2 Answers2

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When you're updating your template. It will not look into the file referenced on S3 to see if anything has changed. So it will simply see that the file location has not changed and conclude that there is no change in the template itself.

Since your question is not really complete, I'll have to answer based on some assumptions. You could enable versioning on the S3 bucket that holds your definition and pass in the S3 version identifier as a parameter to your stack to use as a property of your StepFunction S3 Location declaration. If you do this, you can upload a new version of the state machine declaration to S3 and use that version identifier as a parameter for updating your CloudFormation stack.

You could automate the entire process of updating the CloudFormation stack by using a CodePipeline or a Lambda trigger on S3 to automatically update the CloudFormation stack when a new StateMachine definition is uploaded.

stijndepestel
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  • I think another option may be to include a stack property where the Key is the Stepfunction template filename, and the Value is a hash of the file contents - e.g. md5 or similar. The stack should update when the file contents change. See this post for more details: https://stackoverflow.com/questions/46824171/how-do-i-force-a-cloudformation-stack-to-update-when-the-parameter-is-updated#:~:text=There%20is%20a%20way%20to,CloudFormation%3A%3AInit%20in%20metadata. – racc Feb 16 '22 at 01:13
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The issue with BuildVersion approach was, this parameter was not participating in the AWS resource creation and updating this parameter though CLI does not affecting any thing in the change set.

I have added this parameter in the 'Tag' section of the state machine Resource and it worked for me.

Vicky
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