How does Pulumi decide which provider to use in the

providers

map (in the opt object)?

It's a legacy design that

providers

is a map 😞 The dotnet sdk for example it's just a list. Choosing a provider from there is just a case of looking for the provider with a matching package. So no you can't have multiple AWS providers in the one map/list.

Fair enough. How does it decide which package a resource belongs to? Could that logic be abused by something simple like decorators or even

import * as aws-uswest2 from "@pulumi/pulumi-aws

...?

It's by the type custom resources declare in their constructor. eg. https://github.com/pulumi/pulumi-aws/blob/master/sdk/nodejs/accessanalyzer/analyzer.ts#L59 states that this is the "aws" package, the "accessanalyzer/analyzer" module, and the "Analyzer" type. So no it's not easily abused. Sounds like you've got an interesting use case though, worth opening an issue at github we can give it a proper think over how to help with what your doing.

It could be done by ComponentResources though. You'd have to stick the target env name in the first part of the component resource's URN, but having

myproj-prod:x:y:z:foo

map to provider myproj-prod which is actually an AWS provider hooked up to us-west-2 would be fine.. if it works.

Well if your doing logic in ComponentResources then you can just edit the providers list that it passes around to child resources. Changing the package of the ComponentResource won't actually do anything because ComponentResources don't use providers (they aren't real cloud resources)

True.