Client address is set to server address in new semconv

[y-young]

Describe your environment

OS: (e.g, Windows)
Python version: (e.g., Python 3.10.16)
Package version: (e.g., 0.51b0)

What happened?

With OTEL_SEMCONV_STABILITY_OPT_IN=http, the client.address in server span is wrongly set to server address.

It it because the middleware calls _set_http_host_server and the client.address is set for the first time to server address here:

opentelemetry-python-contrib/opentelemetry-instrumentation/src/opentelemetry/instrumentation/_semconv.py

Line 357 in 3708604

set_string_attribute(result, CLIENT_ADDRESS, host)

When it calls _set_http_peer_ip_server later on, since the client.address is already set, this has no effect:

opentelemetry-python-contrib/opentelemetry-instrumentation/src/opentelemetry/instrumentation/_semconv.py

Lines 368 to 371 in 3708604

	if _report_new(sem_conv_opt_in_mode):
	# Only populate if not already populated
	if not result.get(CLIENT_ADDRESS):
	set_string_attribute(result, CLIENT_ADDRESS, ip)

This was changed in #2814.

Steps to Reproduce

Tested with a minimal FastAPI application: https://github.com/y-young/opentelemetry-fastapi-test

Expected Result

The client address should be correct.

Actual Result

Without OTEL_SEMCONV_STABILITY_OPT_IN

Scope: {'type': 'http', 'asgi': {'version': '3.0', 'spec_version': '2.3'}, 'http_version': '1.1', 'server': ('127.0.0.1', 8000), 'client': ('127.0.0.1', 54737), 'scheme': 'http', 'root_path': ''}

Span:

{
    "name": "GET /",
    "context": {
        "trace_id": "0x3d94c2edf94a8c68e66a261883939a70",
        "span_id": "0x26a8e38e79afe0ae",
        "trace_state": "[]"
    },
    "kind": "SpanKind.SERVER",
    "parent_id": null,
    "start_time": "2025-03-11T14:42:33.575716Z",
    "end_time": "2025-03-11T14:42:33.582507Z",
    "status": {
        "status_code": "UNSET"
    },
    "attributes": {
        "http.scheme": "http",
        "http.host": "127.0.0.1:8000",
        "net.host.port": 8000,
        "http.flavor": "1.1",
        "http.target": "/",
        "http.url": "http://127.0.0.1:8000/",
        "http.method": "GET",
        "http.server_name": "127.0.0.1:8000",
        "http.user_agent": "",
        "net.peer.ip": "127.0.0.1",
        "net.peer.port": 54737,
        "http.route": "/",
        "http.status_code": 200
    },
    "events": [],
    "links": [],
    "resource": {
        "attributes": {
            "service.name": "test-app"
        },
        "schema_url": ""
    }
}

The net.peer.ip and net.peer.port here is correct.

With OTEL_SEMCONV_STABILITY_OPT_IN

Set os.environ["OTEL_SEMCONV_STABILITY_OPT_IN"] = "http" and restart the app:

Scope: {'type': 'http', 'asgi': {'version': '3.0', 'spec_version': '2.3'}, 'http_version': '1.1', 'server': ('127.0.0.1', 8000), 'client': ('127.0.0.1', 50644), 'scheme': 'http', 'root_path': ''}

Span:

{
    "name": "GET /",
    "context": {
        "trace_id": "0xc37fa0f9c920df31a3f6966771f70ce4",
        "span_id": "0x8799fdefa09e60b1",
        "trace_state": "[]"
    },
    "kind": "SpanKind.SERVER",
    "parent_id": null,
    "start_time": "2025-03-11T14:39:09.180212Z",
    "end_time": "2025-03-11T14:39:09.185639Z",
    "status": {
        "status_code": "UNSET"
    },
    "attributes": {
        "url.scheme": "http",
        "client.address": "127.0.0.1:8000",
        "server.port": 8000,
        "network.protocol.version": "1.1",
        "url.path": "/",
        "http.request.method": "GET",
        "user_agent.original": "",
        "client.port": 50644,
        "http.route": "/",
        "http.response.status_code": 200
    },
    "events": [],
    "links": [],
    "resource": {
        "attributes": {
            "service.name": "test-app"
        },
        "schema_url": ""
    }
}

The client.address is set to 127.0.0.1:8000, which is the server address.

Additional context

No response

Would you like to implement a fix?

Yes