Jaeger Missing Spans — Async Context Propagation Fix

# pip install opentelemetry-distro opentelemetry-exporter-otlp
# pip install opentelemetry-instrumentation-fastapi

from fastapi import FastAPI
from opentelemetry import trace
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor

# Configure tracer
provider = TracerProvider()
exporter = OTLPSpanExporter(endpoint='http://jaeger:4317')  # Jaeger OTLP endpoint
provider.add_span_processor(BatchSpanProcessor(exporter))
trace.set_tracer_provider(provider)

app = FastAPI()
FastAPIInstrumentor.instrument_app(app)  # auto-instruments all routes

tracer = trace.get_tracer(__name__)

@app.get('/orders/{order_id}')
async def get_order(order_id: int):
    with tracer.start_as_current_span('fetch-order') as span:
        span.set_attribute('order.id', order_id)

        # Manual span for a specific operation
        with tracer.start_as_current_span('db-query'):
            order = await db.get_order(order_id)

        with tracer.start_as_current_span('enrich-order'):
            user = await user_service.get_user(order.user_id)  # cross-service call

        return {'order': order

# Run Jaeger all-in-one (development setup)
docker run -d \n  --name jaeger \n  -p 16686:16686 \n  -p 4317:4317 \n  -p 4318:4318 \n  jaegertracing/all-in-one:latest

# Ports:
# 16686 — Jaeger UI
# 4317  — OTLP gRPC receiver
# 4318  — OTLP HTTP receiver

# Open Jaeger UI: http://localhost:16686
# Search by service name → see all traces
# Click a trace → see full span timeline
# Click a span → see attributes, events, errors

import requests
from opentelemetry import propagators, trace
from opentelemetry.propagate import inject, extract

# Sending service
tracer = trace.get_tracer(__name__)
with tracer.start_as_current_span('outgoing-call') as span:
    headers = {}
    inject(headers)  # injects traceparent from current span
    response = requests.get('http://payment-service/process', headers=headers)

# Receiving service
# In middleware or at route entry, extract context
from opentelemetry.propagate import extract
ctx = extract(request.headers)
with tracer.start_as_current_span('process-payment', context=ctx) as span:
    # this span is now child of the sending service's span
    pass

# Remote sampling configuration for Jaeger
service_config:
  - service: "order-service"
    operation: "/orders/{id}"
    probabilistic_sampling:
      sampling_rate: 0.01  # 1% sample
  - service: "order-service"
    operation: "*"
    probabilistic_sampling:
      sampling_rate: 0.005  # 0.5% for other ops
  - service: "payment-service"
    operation: "*"
    probabilistic_sampling:
      sampling_rate: 0.05  # 5% for payment (higher risk)

import structlog
from opentelemetry import trace

span = trace.get_current_span()
trace_id = format(span.get_span_context().trace_id, '032x')
span_id = format(span.get_span_context().span_id, '016x')

# Inject trace context into log
logger = structlog.get_logger()
logger.info("payment processed", trace_id=trace_id, span_id=span_id, order_id=123)