# Jaeger — CNCF Distributed Tracing Platform

> Jaeger is a CNCF-graduated distributed tracing system for monitoring microservice-based architectures. Track requests across services, identify latency hotspots, and understand root causes of failures in complex distributed systems.

## Install

Save in your project root:

## Quick Use

```bash
# All-in-one dev container
docker run -d --name jaeger \
  -e COLLECTOR_ZIPKIN_HOST_PORT=:9411 \
  -p 16686:16686 \
  -p 4317:4317 \
  -p 4318:4318 \
  -p 9411:9411 \
  jaegertracing/all-in-one:latest

# UI at http://localhost:16686
```

Instrument an app with OpenTelemetry (Node.js):
```bash
npm i @opentelemetry/sdk-node @opentelemetry/auto-instrumentations-node \
      @opentelemetry/exporter-trace-otlp-http
```

```ts
// tracing.ts
import { NodeSDK } from "@opentelemetry/sdk-node";
import { getNodeAutoInstrumentations } from "@opentelemetry/auto-instrumentations-node";
import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-http";

const sdk = new NodeSDK({
  serviceName: "tokrepo-api",
  traceExporter: new OTLPTraceExporter({
    url: "http://localhost:4318/v1/traces",
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();
```

Run with `node --require ./tracing.ts dist/server.js` — HTTP, DB, and framework calls are auto-traced.

## Intro

Jaeger is a CNCF-graduated distributed tracing platform originally developed at Uber. Jaeger captures, stores, and visualizes traces — sequences of spans showing how a request flows through multiple microservices. Essential for debugging latency and failures in distributed systems.

- **Repo**: https://github.com/jaegertracing/jaeger
- **Stars**: 22K+
- **Language**: Go
- **License**: Apache 2.0

## What Jaeger Does

- **Trace collection** — receive spans via OTLP, Jaeger protocol, Zipkin
- **Storage backends** — Elasticsearch, Cassandra, Kafka, Badger, memory
- **Query API** — search traces by service, operation, tags, duration
- **UI** — waterfall view of spans, service dependencies graph
- **Sampling** — adaptive, probabilistic, rate-limited
- **Service Performance Monitoring (SPM)** — RED metrics from traces
- **Critical Path** — highlight bottleneck spans

## Architecture

Jaeger components:
- **Agent** (deprecated, use OTLP) — local daemon
- **Collector** — receives spans, writes to storage
- **Query** — serves UI and API, reads from storage
- **Ingester** — for Kafka async pipeline
- **All-in-one** — dev container bundling everything
- **OpenTelemetry Collector** — modern ingestion preferred

## Self-Hosting

```yaml
# Production deployment
components:
  - Collector (multi-replica, behind LB)
  - Elasticsearch cluster (storage)
  - Query service (multi-replica)
  - OTel Collector (ingestion)
```

Kubernetes: use the official Jaeger Operator or Helm charts.

## Key Features

- OpenTelemetry native ingestion
- Multiple storage backends
- Service dependency graph
- Adaptive sampling
- Trace search and filtering
- RED metrics (SPM)
- Zipkin compatibility
- gRPC and HTTP APIs
- Kubernetes operator

## Comparison

| Tracing | Storage | OTel | Metrics |
|---|---|---|---|
| Jaeger | ES, Cassandra, Kafka | Yes | SPM |
| Tempo | Object storage | Yes | Via Grafana |
| Zipkin | ES, MySQL, Cassandra | Yes | Partial |
| Honeycomb | Managed | Yes | Yes |
| Lightstep | Managed | Yes | Yes |
| OpenTelemetry Collector | Any backend | Native | Yes |

## 常见问题 FAQ

**Q: Jaeger vs Tempo？**
A: Jaeger 有独立 UI、成熟生态；Tempo 把 trace 存对象存储（便宜），用 Grafana 查看，和 Loki/Prometheus 集成更好。

**Q: 采样策略？**
A: 生产环境不要采 100%（浪费存储）。用 probabilistic 1% + 基于 tag 的 force-keep（错误、慢请求必留）。

**Q: 和 OpenTelemetry 关系？**
A: OTel 是标准（API + SDK + Collector），Jaeger 是后端。新项目应用 OTel 采集 + Jaeger 存储查询。

## 来源与致谢 Sources

- Docs: https://www.jaegertracing.io/docs
- GitHub: https://github.com/jaegertracing/jaeger
- License: Apache 2.0

---
Source: https://tokrepo.com/en/workflows/011420a5-35f7-11f1-9bc6-00163e2b0d79
Author: AI Open Source