ASGI middleware sets server span status code only if inner spans are recording

[bastbu]

Describe your environment

• Python 3.11.7
• Version 0.42b0 of opentelemetry-instrumentation, opentelemetry-instrumentation-asgi and opentelemetry-instrumentation-fastapi

Steps to reproduce

When dropping "http send" spans tracked by the ASGI middleware by using the following sampler:

class DropSampler(StaticSampler):
    def __init__(self, decision: Decision):
        super().__init__(decision)

    def should_sample(
        self,
        parent_context,
        trace_id,
        name,
        kind = None,
        attributes = None,
        links = None,
        trace_state = None,
    ) -> Any:
        if "http send" in name.lower():
            return SamplingResult(decision=Decision.DROP)

        return super().should_sample(
            parent_context,
            trace_id,
            name,
            kind,
            attributes,
            links,
            trace_state,
        )

it exports the following trace as the server span:

{
    "name": "GET /metrics",
    "context": {
        "trace_id": "0x1d9414309f3fd3008fef261573d7b7b4",
        "span_id": "0x3d77a38eb9e6405a",
        "trace_state": "[]"
    },
    "kind": "SpanKind.SERVER",
    "parent_id": null,
    "start_time": "2023-12-13T13:08:41.458169Z",
    "end_time": "2023-12-13T13:08:41.460419Z",
    "status": {
        "status_code": "UNSET"
    },
    "attributes": {
        "http.scheme": "http",
        "http.host": "127.0.0.1:5000",
        "net.host.port": 5000,
        "http.flavor": "1.1",
        "http.target": "/metrics",
        "http.url": "http://127.0.0.1:5000/metrics",
        "http.method": "GET",
        "http.server_name": "localhost:5000",
        "http.user_agent": "curl/7.88.1",
        "net.peer.ip": "127.0.0.1",
        "net.peer.port": 50818,
        "http.route": "/metrics"
    },
    "events": [],
    "links": [],
    "resource": {
        "attributes": {
            "service.name": "some_service"
        },
        "schema_url": ""
    }
}

However, if we do not drop any HTTP send spans, the server span contains the HTTP status code:

{
    "name": "GET /metrics",
    "context": {
        "trace_id": "0x27fc3b66d067ed4ba043668991074e9d",
        "span_id": "0x8a0f4218411adec8",
        "trace_state": "[]"
    },
    "kind": "SpanKind.SERVER",
    "parent_id": null,
    "start_time": "2023-12-13T13:12:53.385801Z",
    "end_time": "2023-12-13T13:12:53.387893Z",
    "status": {
        "status_code": "UNSET"
    },
    "attributes": {
        "http.scheme": "http",
        "http.host": "127.0.0.1:5000",
        "net.host.port": 5000,
        "http.flavor": "1.1",
        "http.target": "/metrics",
        "http.url": "http://127.0.0.1:5000/metrics",
        "http.method": "GET",
        "http.server_name": "localhost:5000",
        "http.user_agent": "curl/7.88.1",
        "net.peer.ip": "127.0.0.1",
        "net.peer.port": 59612,
        "http.route": "/metrics",
        "http.status_code": 200
    },
    "events": [],
    "links": [],
    "resource": {
        "attributes": {
            "service.name": "some_service"
        },
        "schema_url": ""
    }
}

Note the absence/presence of the http.status_code attribute.

What is the expected behavior?

The http.status_code attribute should be present on the server span independently of whether a child span is sampled or not.

What is the actual behavior?

The http.status_code attribute is only present on the server span if the "http send" child span is sampled.

Additional context

This is likely a consequence of the following:

https://github.com/open-telemetry/opentelemetry-python-contrib/blob/4bf3577fb76480dacca12eecd8ed93cb9fccc274/instrumentation/opentelemetry-instrumentation-asgi/src/opentelemetry/instrumentation/asgi/__init__.py#L668-L674C23

The set_status_code(server_span, status_code) is only invoked if send_span.is_recording(), whereas it should be invoked if the server_span itself is recording.

[bastbu]

I see now that this is a duplicate of #1876. Closing this issue.