good morning! i'm curious about some of the inner workings of ComponentResource. does anybody know if there's a difference between setting a component property vs using registerOutput . for instance in this example, why use

registerOutputs({bucketName: ....})

instead of just declaring and setting

this.bucketName

RegisterOutputs

signals that the

ComponentResource

is done creating child resources and is mainly for quicker UI updates. It will not affect the dep graph. Specifically for TS, see: https://github.com/pulumi/pulumi/blob/510111fe67666834b7e7ed43242ac60a3eaa524e/sdk/nodejs/resource.ts#L1280 and https://github.com/pulumi/pulumi/blob/510111fe67666834b7e7ed43242ac60a3eaa524e/sdk/nodejs/runtime/resource.ts#L1131

@future-hairdresser-70637 ah, interesting. it seems weird to signal that it's done creating when that always fires before the child constructor is finished

is there any reason to use

initialize

over putting all of the logic in the constructor?

I would say no, as

ComponentResource

is "just" a container for other resources; more of an organizational/reuse thing than an actual Resource. I want to say I've seen an example or two that overrode

initialize

but I can't think of where/why

@future-hairdresser-70637 that makes total sense. it feels like maybe those are vestiges of maintaining parity with

Resource

i would still recommend following the best practices of the docs and call it

The call to

registerOutputs

also tells Pulumi that the resource is done registering children and should be considered fully constructed, so—although it’s not enforced—the best practice is to call it in all components even if no outputs need to be registered.

there's no absolute guarantee that this will stay unenforced

that's the part that's misleading though

class Foo extends ComponentResource {
  constructor(......) {
    super(....)
    // registerOutputs was called by super
    new FooResource(....)
    // but we're not done creating resources
  }
}

@steep-secretary-65224 🤔 it doesn't show up without the call to

registerOutputs

?

nope. and if you try to call it in the constructor, it short circuits because it was already called at the end of the

super

call

I would very lightly argue that's a somewhat contrived example there because of the input

args

-> output

retval

? that is, it's expected the

ComponentResource

will do "stuff" such as have resources with their

parent

==

this

hmm, that's a good point

i agree this is still documented... oddly, at best, and not with sufficient "but why do we do this?" aside from "because we say to (and it updates the UI)" :)

agreed. given that you can't really create resources, i think the only real use would be like my example, where you might be calculating values, fetching resources (eg,

aws.route53.getZone

), etc

🙂

heh, it's nice to see i had the same gut reaction as @white-balloon-205