[Gen 2] Support cross-region functions

[ykethan]

Describe the feature you'd like to request

similar to gen 1: https://docs.amplify.aws/gen1/react/build-a-backend/graphqlapi/custom-business-logic/#calling-functions-in-different-regions
reference a existing function in gen 2 can be done using a.handler.function('<function-name>')
but cross region isnt supported

Describe the solution you'd like

a.handler.function('<function-name>', '<region>')

Describe alternatives you've considered

override backend.ts to addLambdaDataSource

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request

Would this feature include a breaking change?

• ⚠️ This feature might incur a breaking change

[JGamboa]

Basically the idea is to have some of the functions on another regions because of latency.

On my case we have to connect to apis on different countries, this countries have low bandwitch to US, so creating the function on for example SA give us better performance, even when the appsync is on the US.

APP SYNC US -> LAMBDA US ->>> SA COUNTRY -->> LOW RESPONSE
APP SYNC US -> LAMBDA SA ->>> SA COUTRY ---> FAST RESPONSE

[JGamboa]

Any update on this?

[JGamboa]

Any update on this @stocaaro

[stocaaro]

Hello @JGamboa,

This is an interesting feature request. Do you have a Gen 1 example app you can share that demonstrates the performance improvement you have diagrammed above? I'm not sure where supporting this behavior fits into our feature backlog and I'll check.

Thanks,
Aaron

[JGamboa]

@stocaaro I modified the arn of the used function on the UI. I created the function on the other region manually, after i copied the arn, and in the appsync where you have the resolver i choose and put manually the arn of the function of the other region.

I tested a lot of times with multiple request, using the lambda on us (original) response time was arround 4 seconds on lambda + the response to go back to the appsync, and when using it on the sa country, response time of lambda was arround 1.5 seconds + resposne back (this was really faster as you seeing)

Nop i started using gen 2 of amplify so i dont have a gen1 example, i just tested manually changing the arns

[JGamboa]

I think that maybe adding sometihng like "put your arn of lambda function here" could be easy, beacuse that way you dont need the lambd function that is in the other region to be part of the stack, and can be created manually.