Support more span attributes in the AWS lambda wrapper

[mateuszrzeszutek]

The aim of this issue is to introduce support for most of the FAAS/cloud attributes defined in the spec. Currently only faas.execution is added to the span.

I think that the following attributes can be added pretty easily:

• cloud.provider
• cloud.region
• faas.name
• faas.version
• faas.id - this one is interesting, because it's marked as a resource attribute in the spec; in the context of AWS lambda functions ARN is used here and with the current implementation it's impossible to add it as a resource (because it can only be extracted from a lambda Context passed as a function parameter; the tracer is initialized before that happens)

Also, I'm planning to file a new spec issue so that the following things can be added (so this story will probably evolve in time):

• execution environment
• account id
• function qualifier

For APIGatewayProxyRequestEvents I believe that we can implement most of the HTTP server spec - not sure about other event types though.

[anuraaga]

this one is interesting, because it's marked as a resource attribute in the spec

Yup this one probably needs an update in the spec.

account id

I think this is cloud.account.id
https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/resource/semantic_conventions/cloud.md

[anuraaga]

For resource attributes, it probably makes sense to keep them together with other resource providers instead of instrumentation, so adding LambdaResource here - https://github.com/open-telemetry/opentelemetry-java/tree/master/sdk-extensions/aws/src/main/java/io/opentelemetry/sdk/extension/aws/resource

[mateuszrzeszutek]

I think this is cloud.account.id

Nice! It was absent from the trace semantic conventions doc - I should probably add it there.

For resource attributes, it probably makes sense to keep them together with other resource providers instead of instrumentation, so adding LambdaResource here

Yep, that was exactly my intention, but in the Javaagent. I think that putting it in otel-java makes more sense though -- will add it there. Thanks for the suggestion!

[mateuszrzeszutek]

By the way @anuraaga : do you know if it's possible to get the account id from something other than the ARN? My idea was to just extract it from the ARN, but then again it cannot be a resource attribute.

[mateuszrzeszutek]

Also, regarding the execution environment: I thought about it and decided to use more generic process.runtime.* attributes instead. I'll create an issue & PR in otel-java.