How to determine when cdk deploy is run?

[rnag]

Hi there,

I have an interesting question, but I would like to know if there is any way within a CDK app to know which cdk subcommand was invoked. Specifically, I am just trying to distinguish between cdk deploy and between other similar commands, such as cdk synth and cdk destroy.

I think at a minimum, it would be good enough to know if we are only deploying a CDK app or not (i.e. if cdk deploy is being run).

Use case/scenario

I can briefly go into the specifics of why this is an important question for me:
So in my use case, I basically create a custom CDK construct. Let's say this construct can sometimes take a long time to build/run - so for example it can take up to 5 minutes to resolve the construct, which is fine for the build/deploy step when cdk deploy is run. However, in other cases, such as when cdk synth is run, I would like to skip this sometimes expensive logic, and maybe just return with a dummy file or artifact. Hence, I was curious to know if there exists a way currently to determine if we are in a deploy-related scenario or not - such as for example when cdk destroy is run, we are only interested in cleaning up the stack and we won't need to run the whole construct logic in such a scenario.

[calavera]

I think what you need is to extract the building logic and put it in the bundling property in the asset. That way, the building logic will only be executed during build/deploy in the cdk. Look at the construct for Go Lambda functions, I think it's something similar:

https://github.com/aws/aws-cdk/blob/main/packages/%40aws-cdk/aws-lambda-go/lib/bundling.ts#L73-L83

[bestickley]

I'd hoped that process.argv would reveal this information but it only show information of the "app" command in cdk.json :(

[bestickley]

@calavera's answer is best. See more help here: https://dev.to/aws-builders/aws-cdk-fullstack-polyglot-with-asset-bundling-318h

[bestickley]

I'm not sure if this is new, but now you can use Stack.of(this).bundlingRequired boolean property to determine if you should bundle.