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.

requirements.txt

azure-functions
azure-functions-durable
azure-monitor-opentelemetry
opentelemetry-api
opentelemetry-sdk

Client Function code

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