aws-ecs (all): validation should leverage typescript type system

[cheruvian]

Describe the feature

Audit either/or validations across the CDK and add appropriate types to the interfaces for build time validation rather than runtime validation.

Use Case

I've seen this in a couple places but most recently with

this.taskDefinition.addFirelensLogRouter('FluentBitLogRouter', {
      image: ContainerImage.fromRegistry('amazon/aws-for-fluent-bit:latest'),
      firelensConfig: {
        type: FirelensLogRouterType.FLUENTBIT,
        options: {
          enableECSLogMetadata: true,
        },
      },
}

Which results in the following error

ECS Container FluentBitLogRouter must have at least one of 'memoryLimitMiB' or 'memoryReservationMiB' specified

Proposed Solution

Current:

addFirelensLogRouter(id: string, props: FirelensLogRouterDefinitionOptions): FirelensLogRouter;

Proposed:

addFirelensLogRouter(id: string, props: FirelensLogRouterDefinitionOptions & ({ memoryLimitMiB: number } | { memoryReservationMiB: number })): FirelensLogRouter;

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

all

Environment details (OS name and version, etc.)

OSX

[luxaritas]

From my understanding, these kinds of API definitions are explicitly avoided since many target languages of the CDK can't represent them: https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md#unions

[pahud]

That's right. Thank you.

[cheruvian]

While I understand the need, as a majority of documentation and, from my understanding, usage is TypeScript we should consider improving the native TypeScript usage.

The approach would seem to be to fairly straightforward to resolve and merge the type in as optional for languages that do not support unions.

e.g.

interface Reqs { a: number }
interface Opt1 { b: number }
interface Opt2 { c: number }
type API = Reqs & (Opt1 | Opt2)

// becomes

type API_M = Reqs & Optional<Opt1> & Optional<Opt2>

I'm certain an actual jsii implementation would require some thought but it seems achievable at first glance.