Introduce a new resource attribute for AWS Lambda function alias

[mateuszrzeszutek]

What are you trying to achieve?

I propose adding a new optional resource attribute that will store the AWS Lambda function alias (if it's used at all), named aws.lambda.alias.

Additional context.

• AWS Lambda alias docs

[thisthat]

Currently, the alias is caught inside the faas.id attribute.
Do you think it would be better to remove the alias from the id attribute and report it inside aws.lambda.alias?

[Oberon00]

I'm wondering about that: If a function has multiple aliases, would a request to one alias re-use an instance started by a request to another alias (or the un-aliased ARN)? If so, then we must not report the AWS alias in faas.id when used as resource attribute.

[Oberon00]

Relatedly, #1265 allows faas.id as span attribute.

[mateuszrzeszutek]

I'm wondering about that: If a function has multiple aliases, would a request to one alias re-use an instance started by a request to another alias (or the un-aliased ARN)?

That's a very good question. I don't know that -- I'll test it and come back here with the answer.