Observability & Distributed Tracing

# Python OpenTelemetry Manual Span Tracing
from opentelemetry import trace

tracer = trace.get_tracer("checkout-service")

async def process_checkout(order_id: str, amount: float):
    with tracer.start_as_current_span("process_checkout") as span:
        span.set_attribute("order.id", order_id)
        span.set_attribute("order.amount", amount)

        # Child span for DB query
        with tracer.start_as_current_span("inventory.reserve_sql") as db_span:
            db_span.set_attribute("db.system", "postgresql")
            await execute_sql("SELECT * FROM inventory WHERE id = %s", order_id)

        return {"status": "SUCCESS"}

// C++ OpenTelemetry SDK Tracing
#include <opentelemetry/trace/provider.h>

void processPayment(const std::string& orderId, double amount) {
    auto tracer = opentelemetry::trace::Provider::GetTracerProvider()->GetTracer("payment-svc");
    auto span = tracer->StartSpan("charge_card");
    span->SetAttribute("order.id", orderId);
    span->SetAttribute("payment.amount", amount);

    // Execute payment network call
    callStripeApi(amount);
    span->End();
}

// Java OpenTelemetry Instrumentation
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.extension.annotations.WithSpan;

public class OrderService {
    @WithSpan("createOrder")
    public Order createOrder(String orderId) {
        Span currentSpan = Span.current();
        currentSpan.setAttribute("order.id", orderId);
        return db.saveOrder(orderId);
    }
}

// Go OpenTelemetry Context Propagation
package main

import (
    "context"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
)

func ProcessOrder(ctx context.Context, orderID string) error {
    tr := otel.Tracer("order-service")
    ctx, span := tr.Start(ctx, "ProcessOrder")
    defer span.End()

    span.SetAttributes(attribute.String("order.id", orderID))
    return callInventory(ctx, orderID) // ctx carries W3C traceparent!
}

// TypeScript OpenTelemetry Trace SDK
import { trace } from '@opentelemetry/api';

const tracer = trace.getTracer('checkout-service');

export async function handleCheckout(orderId: string) {
  return tracer.startActiveSpan('handleCheckout', async (span) => {
    span.setAttribute('order.id', orderId);
    try {
      await reserveInventory(orderId);
      span.setStatus({ code: 1 }); // SpanStatusCode.OK
    } finally {
      span.end();
    }
  });
}