Django instrumentation doesn't include http.route attribute in http.server.duration metrics

[johns-agentio]

Describe your environment

OS: macOS
Python version: 3.12.7
Package version: 0.53b1

What happened?

Django instrumentation doesn't set http.route attribute on metrics.

Steps to Reproduce

Sample instrumentation setup:

from opentelemetry import metrics
from opentelemetry.instrumentation.django import DjangoInstrumentor
from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import ConsoleMetricExporter
from opentelemetry.sdk.metrics.view import View

# Set up console exporter to see metrics
exporter = ConsoleMetricExporter()
reader = PeriodicExportingMetricReader(exporter=exporter, export_interval_millis=5000)

# View expecting http.route
view = View(
    instrument_name="http.server.duration",
    attribute_keys={"http.method", "http.status_code", "http.route"}
)

meter_provider = MeterProvider(
    metric_readers=[reader],
    views=[view]
)
metrics.set_meter_provider(meter_provider)

DjangoInstrumentor().instrument(is_middleware=True)

Expected Result

Console output should show a metric that includes http.route, compared to the actual console output below.

Actual Result

Console output:

...
                            "name": "http.server.duration",
                            "description": "Measures the duration of inbound HTTP requests.",
                            "unit": "ms",
                            "data": {
                                "data_points": [
                                    {
                                        "attributes": {
                                            "http.method": "GET",
                                            "http.status_code": 200
                                        },
...

Additional context

Note that I AM able to see the http.route in the response hook and set it on a span, like so:

    def set_http_route_attribute_response_hook(span, request, response):
        if hasattr(request, "resolver_match") and request.resolver_match:
            route = request.resolver_match.route
            span.set_attribute("http.route", str(route))

    DjangoInstrumentor().instrument(
        is_middleware=True,
        response_hook=set_http_route_attribute_response_hook,
    )

I can also see http.target correctly, just not http.route.

Would you like to implement a fix?

Probably not