Add support to send trace information to the WebJobs extension

[bachuv]

This PR introduces support for propagating trace information to the WebJobs extension by getting the traceparent and tracestate information in the start_new method by accessing the "current span" information. traceparent and tracestate are then forwarded to the post_async_request method, which now accepts trace_parent and trace_state parameters in http_utils.py to include them in the outgoing request. trace_parent and trace_state parameters are now set as the headers in the POST request to the WebJobs extension.

In the example below, I used the HTTP trigger's traceparent and tracestate as the parent context of a new span that I created. I then set that new span as the current span before calling start_new().

Note: I followed the Azure Function OpenTelemetry set up in this example which is also emitting spans for storage requests and that's why there are spans for storage operations.

import azure.functions as func
import azure.durable_functions as df
import opentelemetry.context as context_api

from azure.monitor.opentelemetry import configure_azure_monitor
from opentelemetry import trace
from opentelemetry.trace import SpanKind
from opentelemetry.trace.propagation.tracecontext import TraceContextTextMapPropagator

configure_azure_monitor()
tracer = trace.get_tracer(__name__)

myApp = df.DFApp(http_auth_level=func.AuthLevel.ANONYMOUS)

# An HTTP-triggered function with a Durable Functions client binding
@myApp.route(route="orchestrators/{functionName}")
@myApp.durable_client_input(client_name="client")
async def http_start(req: func.HttpRequest, client, context: func.Context):
    function_name = req.route_params.get('functionName')

    # Extract the traceparent and tracestate from the context
    parent = {
        "traceparent": context.trace_context.trace_parent,
        "tracestate": context.trace_context.trace_state
    }
    parent_context = TraceContextTextMapPropagator().extract(parent)

    # Create a new span with the extracted parent context
    with tracer.start_as_current_span(
            "myCustomSpan",
            context=parent_context,
            kind=SpanKind.CLIENT) as span:
        
        span.set_attribute("az.namespace", "app")

        instance_id = await client.start_new(function_name)
        response = client.create_check_status_response(req, instance_id)
    return response

[andystaples]

Left some comments

[cgillum]

Agreed with @andystaples feedback. Otherwise, I'm good with these changes.

[andystaples]

Looks good