Allow reference against specific version of function #240
Description
This is a Feature Proposal
Description
To make it easy to implement blue-green deployments for step functions (hence ensuring that running executions are not affected by deployments), we can add a configuration option to reference the current version of functions.
e.g.
stepFunctions:
stateMachines:
myStateMachine:
name: blah
useExactVersion: true # default to false for backward compatibility
definition:
StartAt: Hello
States:
Hello:
Type: Task
Resource:
Fn::GetAtt: [hello, Arn] # we'll replace this
End: true
When useExactVersion is true, we can swap out the function ARN with the ARN of the version to be deployed.
We'll also need to adjust the IAM roles that are generated to allow InvokeFunction permission on all versions (e.g. arn:aws:lambda:us-east-1:123456789012:function:hello:*) as well. Otherwise, after a deploy, the existing executions would lose the ability to invoke the previous version of the functions.
More info on how I managed to do this with alias instead of versions: https://theburningmonk.com/2019/08/how-to-do-blue-green-deployment-for-step-functions/