[Resolves #1264] Update AWS CDK Example for CDK v2 and Asset Support

[X-Guardian]

Updates the AWS CDK example for CDK v2 and adds asset support.

• Resolves The Sceptre Template AWS CDK Example is out of date and does not support CDK Assets #1264

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• Commit message starts with [Resolve #issue-number].
• Added/Updated unit tests.
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[jfalkenstein]

So this documented example is starting to become less of a "recipe" like it was before and more of library code that needs to be copied and pasted. There's a lot going on here and, with the rise of CDK, I think it's important we make this easier to do. Here's what I think would be better:

What if you made a Template Handler that can be installed? We could potentially bootstrap a repo in the Sceptre Org for it. The template handler could work similar to the "file" handler that this example relies upon. Here's how it would be different, though:

1. Rather than having a sceptre_handler() method returning a string, it would have a get_construct_class that returns the construct class.
2. The handler itself would do the synth and asset publishing, returning the string
3. If you wanted to be fancy, you could make it configurable so that it could EITHER take a python file as an argument OR it could use cdk synth to work with projects not in python, then get the published manifest and such from file. (My company's cdk people all insist on using CDK with typescript, despite nobody using typescript for other projects).

To give you an example of what making a template handler looks like, this was a template handler I made for SAM templates: https://github.com/Sceptre/sceptre-sam-handler.

I'd be happy to talk more about this in person. If you get on our slack channel, we can chat and find some time to maybe do a Google Meet and talk about this.

What do you think about this?

[jfalkenstein]

I don't know if I see a point in including this generated CDK stack template in these docs. CDK stacks are SOOOOOO ugly.

[X-Guardian]

Hehe, I thought it was the point to show this.

[jfalkenstein]

Nah. This is too much stuff without much gain. I don't think we need to include the sample generated template here. I just don't see what the reader gains from this.

[X-Guardian]

OK, removed the generated template

[jfalkenstein]

Thanks!

[X-Guardian]

I've also created an initial version of a Sceptre CDK template handler, as per your suggestion. You can take a look at it here: Sceptre/sceptre-cdk-handler#1

[jfalkenstein]

I like where you're going and we definitely need to update these docs, but let's hold off on changing these docs until the template handler is available, and then we can reference the CDK handler in the docs rather than including this rather tricky code sample.

[jfalkenstein]

I'm applying the "On Hold" label to this PR until we can get the Template Handler PR merged/deployed. The instructions will be a lot simpler when we can just say "Use this template handler".

[jfalkenstein]

@X-Guardian, the CDK Handler has now been deployed! You can update the docs here to point to it.

[jfalkenstein]

Closing this as a duplicate of #1285