Applets: allow multi-applet stacks

[rix0rrr]

Requested via email

[Doug-AWS]

Do we have applet support in the current release? Is it P0 for ext. beta/GA?

[eladb]

We do have applet support in the current release. There are missing features such as #291.

[Doug-AWS]

CDK constructs can represent robust and powerful cloud abstractions. Currently, the only way to consume these abstractions is by instantiating these constructs in code into a user's CDK stack and then deploying them either manually using cx toolkit or via a CI/CD pipeline.

For certain use cases we would like to allow users to deploy CDK apps that are based on specific constructs without the need to consume these constructs in code, but rather use a simple declarative format such as a YAML file.

CDK applets are JSON/YAML files that represent fully deployable stacks.

[sasaraf]

Hi, we would like to make usage of the applet to describe different environment of deployment, e.g. to make declarative structure for 'dev|prod|integration' env for example.
However, it seems that we can instantiate only a single 'type' per applet/stack.

we would like to be able to do something like:
applets:
infra-stack:
type: ./network-layer-construct
properties:
name: infra-network
type: ./db-layer-construct
properties:
name: our-db

Will you support such scenario? Thanks

[rix0rrr]

That is true, at the moment one applet corresponds to one stack.

What would you prefer, and how would you use it?

[sasaraf]

Hi, thanks for the fast respond. I assume the best way to describe 'our thoughts' will be using serverless-terminology. hope ok. We tend to think of constructs as our 'plugins', the building blocks that wraps basic logic/concepts. For example, apigw-access-with-cognito-authorizer, apigw-with-private-link, etc. And we wanted a declarative way that can be used by us or system engineer to describe our deployment. Not exactly serverles.yml ,but indeed some kind of format that will help us describe several constructs that builds a single stack. That is why we wanted to ask that each applet=stack, will allow several 'types' children to allow this. could it be useful for others too as you see it? Thanks in advance!

[sasaraf]

Hi, small ping following the above. thanks in advance!

[rix0rrr]

Thanks for your response.

At the moment, we're not planning to implement multi-construct applet stacks. I'm not opposed to it, but I think the gain wouldn't be large enough.

There are no ways to combine constructs together (for example, reference an output of a construct as another construct's input). In the end, each construct in the stack would be standalone. At that point, what's the advantage of even combining them into the same stack? They might as well be deployed separately.

Once we start allow referencing between applets, we're kind of rebuilding CloudFormation, and there's probably something better we could be doing instead.

I will turn this issue into a feature request for that feature, but I can't make any promises on when it will be implemented.

[sasaraf]

Highly appreciate the elaborated consideration of the issue. You explained well. Our thought was to be able to combine into simple small constructs what we refer to as 'best-practice/well-architecture small features', That could be as i mentioned above apigw-connected-with-waf-and-cloud-front, apigw-exposed-via-private-link, etc. Those joint building blocks (turned into constructs) could help build a full featured solution (single stack) that can later on enjoy the good-updates cloudformation supports. etc. However, i do realize it is not high necessity at the moment as we can still enjoy the cdk as is, with coding the above need.
Thanks again! for the good/clear answer.