Remove resource from individual spans

[aabmass]

Steps to reproduce
You can currently set a resource directly on a span:

opentelemetry-python/opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

Line 367 in 9be899e

resource: Resource = Resource.create({}),

My understanding was it should only be in the Tracer/Meter providers since resource is generally a constant throughout the program based on the environment.

What is the expected behavior?
I believe resource should only be attached to the providers.

What is the actual behavior?
Can set it on spans

Additional context
OTLP only has Resource once for all the spans sent in a request: https://github.com/open-telemetry/opentelemetry-proto/blob/30d237e1ff3ab7aa50e0922b5bebdd93505090af/opentelemetry/proto/trace/v1/trace.proto#L28-L31

I couldn't find resource attribute for spans in the tracing spec either.

[lzchen]

Continued from this comment

[lzchen]

Might be related to: https://github.com/open-telemetry/opentelemetry-python/issues/1177

[aabmass]

Is there a use case for dynamically setting the Resource though? How would we even do this? Modify TracerPovider 's resources, create span, and then remove resource from TracerProvider? Seems kind of unecessary.

What are the boto/botocore instrumentations doing it for (could they just use labels)?

Doing this IMO violates the idea of a "a Resource is an immutable representation of the entity producing telemetry". The other issue is OTLP has no span-level resource, besides maybe merging into span attributes.

The OTLP exporter right now groups the spans by span Resource into separate ResourceSpans protos, but I don't think this is right, that would represent multiple instrumentation libraries. It also is not sending the Resource attached to the TracerProvider

[aabmass]

JS actually has this: https://github.com/open-telemetry/opentelemetry-js/blob/f731c65201ef49d91d8ec14ad329d9e485e2bcfb/packages/opentelemetry-tracing/src/Span.ts#L50

[aabmass]

On second look I don't believe the JS SDK has this. It is just passing a reference to the provider's resource in the constructor here and it is not settable by the user.

Same goes for Go after a quick look; there is no way to set resource (https://github.com/open-telemetry/opentelemetry-go/blob/master/sdk/trace/span.go). Also not seeing it in Java.

[srikanthccv]

Jaeger has some inconsistent model definitions about this. Thrift span def doesn't have process field and Batch makes it mandatory. Proto span def has process as mandatory span field and in case of Batch it is nullable.

So, for Jaeger to work with protobuf span should have resource attribute for every span or at least pb2_span should be populated with some resource data.

My understanding was it should only be in the Tracer/Meter providers since resource is generally a constant throughout the program based on the environment.

This makes lot of sense and trace specification doesn't have anything related to resource.

[github-actions]

This issue was marked stale due to lack of activity. It will be closed in 30 days.

[lzchen]

Following this issue, we need the resource to be on the individual spans to populate service_name instead of getting them from the global tracer_provider. Closing this.