实战项目二：完整可观测性平台（LGTM）

                ┌─────────────────────────────────────┐
   应用(OTel SDK)─┼─► OTel Collector ─┬─► Tempo (链路)   │
        │         │                  ├─► Loki  (日志)   │
        │         │                  └─► Prometheus(指标)│
        │         └─────────────────────────────────────┘
        │                    │
        └── /metrics ─────► Prometheus ──► Grafana（统一展示+告警）
                   └── 日志(trace_id) ─► Loki ──► Grafana

services:
  # —— 已有的 ——
  prometheus: { image: prom/prometheus:latest, ports: ["9090:9090"] }
  grafana:    { image: grafana/grafana-oss:11.3.0, ports: ["3000:3000"],
                volumes: ["./grafana/provisioning:/etc/grafana/provisioning"] }
  node-exporter: { image: prom/node-exporter:latest }
 
  # —— 新增：日志 ——
  loki:
    image: grafana/loki:latest
    command: -config.file=/etc/loki/local-config.yaml
    ports: ["3100:3100"]
 
  # —— 新增：链路 ——
  tempo:
    image: grafana/tempo:latest
    command: ["-config.file=/etc/tempo/tempo.yaml"]
    ports: ["3200:3200", "4317:4317"]
 
  # —— 新增：OTel 收集器（统一接收埋点，分发到后端的存储）——
  otel-collector:
    image: otel/opentelemetry-collector-contrib:latest
    command: ["--config=/etc/otel/config.yaml"]
    ports: ["4317:4317", "4318:4318"]

# otel/config.yaml（示意）
receivers:
  otlp:
    protocols: { grpc: { endpoint: 0.0.0.0:4317 }, http: { endpoint: 0.0.0.0:4318 } }
exporters:
  tempo:
    endpoint: tempo:4317
    tls: { insecure: true }
  loki:
    endpoint: http://loki:3100/loki/api/v1/push
  prometheus:
    endpoint: prometheus:9090
processors:
  batch: {}
service:
  pipelines:
    traces:  { receivers: [otlp], processors: [batch], exporters: [tempo] }
    logs:    { receivers: [otlp], processors: [batch], exporters: [loki] }
    metrics: { receivers: [otlp], processors: [batch], exporters: [prometheus] }

# grafana/provisioning/datasources/all.yaml
apiVersion: 1
datasources:
  - { name: Prometheus, type: prometheus, access: proxy, url: http://prometheus:9090, isDefault: true }
  - { name: Loki,      type: loki,      access: proxy, url: http://loki:3100 }
  - { name: Tempo,     type: tempo,     access: proxy, url: http://tempo:3200 }

{"level":"info","trace_id":"abc123","status":200,"path":"/checkout","latency_ms":47}