OpenTelemetry 分散式追蹤

Vibe Prompt

「幫我在 FastAPI 中加上 OpenTelemetry 追蹤，將 trace 匯出到 Jaeger。」

安裝

pip install opentelemetry-distro opentelemetry-exporter-otlp

FastAPI 整合

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

provider = TracerProvider()
processor = BatchSpanProcessor(OTLPSpanExporter(endpoint="http://jaeger:4317"))
provider.add_span_processor(processor)
trace.set_tracer_provider(provider)

app = FastAPI()
FastAPIInstrumentor.instrument_app(app)

@app.get("/api/items/{item_id}")
async def get_item(item_id: int):
    with trace.get_tracer(__name__).start_as_current_span("get_item") as span:
        span.set_attribute("item_id", item_id)
        result = await db.query("SELECT * FROM items WHERE id = ?", item_id)
        span.set_attribute("db.query", "true")
        return result

Jaeger 部署

services:
  jaeger:
    image: jaegertracing/all-in-one:latest
    ports:
      - "16686:16686"  # UI
      - "4317:4317"    # OTLP gRPC
      - "4318:4318"    # OTLP HTTP
    environment:
      COLLECTOR_OTLP_ENABLED: "true"

Span 結構

Trace ID: abc123def456
├── Span: /api/checkout (HTTP POST)
│   ├── Span: validate_cart (0.2ms)
│   ├── Span: process_payment (342ms) ← 瓶頸在這裡！
│   │   ├── Span: stripe.api.charge (310ms)
│   │   └── Span: db.update_order (28ms)
│   └── Span: send_email (45ms)
└──

常見使用場景

• 找出跨服務的效能瓶頸
• 追蹤錯誤的真實根源
• 視覺化微服務呼叫關係