Adding aws.region span attribute to the spec

[Ma-Ba]

We noticed that the AWS SDK instrumentation in various languages sets a (client) span attribute named aws.region which is currently not part of the spec.

I found the following instrumenation libraries that set aws.region:

• https://github.com/open-telemetry/opentelemetry-ruby/blob/main/instrumentation/aws_sdk/lib/opentelemetry/instrumentation/aws_sdk/handler.rb
• https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/opentelemetry-instrumentation-aws-sdk/src/enums.ts
• https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/main/src/OpenTelemetry.Contrib.Instrumentation.AWS/Implementation/AWSSemanticConventions.cs
• https://github.com/open-telemetry/opentelemetry-go-contrib/blob/main/instrumentation/github.com/aws/aws-sdk-go-v2/otelaws/attributes.go
• https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/instrumentation/opentelemetry-instrumentation-boto/src/opentelemetry/instrumentation/boto/__init__.py

Currently, the spec contains the cloud.region resource attribute intended for server-side spans and faas.invoked_region for client-side spans of FaaS invocations. The latter is therefore not suitable for e.g. calls to DynamoDB using the AWS SDK.

I'd like to propose the following:

• document aws.region in the spec as an existing legancy span attribute
• introduce a more generic alternative such as cloud.invoked_region that fits client spans for multiple cloud platforms and SDK call types
• deprecate faas.invoked_region in favor of the new more generic attribute

I am happy to create a PR after the discussion of this issue.

[Oberon00]

invoked_region might not be the ideal name if we also want to use the attribute to e.g. record the region from which some FaaS invocation was triggered. Maybe cloud.peer_region or cloud.remote_region?

[Oberon00]

We might also want to consider the (invoked/peer/remote) account_id here as a complement to the callers cloud.account_id, but that might be considered a separate issue.

[arminru]

@jsuereth can this be added to open-telemetry/opentelemetry-specification#2753?

[jordankay13]

I'm coming here from

• https://github.com/open-telemetry/opentelemetry-dotnet-contrib/issues/1599

I would argue against documenting the current behaviour - aws.region is too similar to cloud.region and is incredibly confusing, especially for new users. I quite like the idea of having a cloud.peer_region attribute.

Thank you