Ability to add a custom domain to a lambda function in amplify gen2

[cookiejest]

Environment information

I have a requirement to create a separate domain for a public api that is protected by a non expiring auth token. The domain should be at api.mydonain.com, my current amplify gen2 app is at www.mydonain.com

What is the best practice way to do this?

Describe the feature

Add a custom domain to an amplify gen2 custom function

Use case

Have a public API that has a separate domain and auth check

[ykethan]

Hey @cookiejest, wanted to better understand your case. Are you looking to create a new API such as AppSync/API gateway with Lambda function as data source and add a custom domain to the API?
or are you looking to add a custom domain to the Amplify hosting branch application on the console?

[cookiejest]

I want to do the equivilent of creating a lambda function and assigning a custom url to the lambda function that is separate from the amplify gen2 domain of the UI application.

Ideally I also want to secure the lambda function using a unique api key per user that is seperate from the authorization of the amplify gen 2 app

[ykethan]

Hey @cookiejest, thank you for the information. AWS Lambda does provide a function URL that can be used to invoke a function but do note that this only provides AWS IAM as auth.

For your use case I would suggest using an API such as REST API(API gateway) or GraphQL(AppSync) that provides these capabilities in using a API key auth and Lambda function as datasource.
https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-setup-api-key-with-console.html
https://docs.aws.amazon.com/appsync/latest/devguide/security-authz.html

[cookiejest]

Ok, I can add the generated lambda function from amplify into a manually configured api gateway for production. Is the url ever likely to change in production during an amplify deploy?

If so is there an example to configure it within amplify.

Thanks,

[ykethan]

Hey @cookiejest, on a branch deploy Amplify will deploy a new Lambda function.
Refer to the following documentation providing a example with various auth modes and Lambda as datasource.
https://docs.amplify.aws/react/build-a-backend/add-aws-services/rest-api/