监控

Metrics 中间件用于实现服务的性能指标监控，统计了请求耗时和请求计数。

配置

Metrics 中间件中提供了两个配置方法 WithSeconds() 和 WithRequests()。

WithSeconds()

func WithSeconds(c metrics.Observer) Option {
  return func(o *options) {
    o.seconds = c
  }
}

用于设置 metrics 中间件统计请求耗时的 Observer 直方图。

WithRequests()

func WithRequests(c metrics.Counter) Option {
  return func(o *options) {
    o.requests = c
  }
}

用于设置 metrics 中间件统计请求计数的 Counter 计数器。

使用方式 (kratos < 2.8.0)

使用 prometheus

// 详见 https://github.com/go-kratos/examples/tree/main/metrics

_metricSeconds = prometheus.NewHistogramVec(prometheus.HistogramOpts{
  Namespace: "server",
  Subsystem: "requests",
  Name:      "duration_sec",
  Help:      "server requests duratio(sec).",
  Buckets:   []float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.250, 0.5, 1},
}, []string{"kind", "operation"})

_metricRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
  Namespace: "client",
  Subsystem: "requests",
  Name:      "code_total",
  Help:      "The total number of processed requests",
}, []string{"kind", "operation", "code", "reason"})

prometheus.MustRegister(_metricSeconds, _metricRequests)

Server 中使用 metrics

import (
  prom "github.com/go-kratos/kratos/contrib/metrics/prometheus/v2"
)

// grpc service
grpcSrv := grpc.NewServer(
  grpc.Address(":9000"),
  grpc.Middleware(
    metrics.Server(
      metrics.WithSeconds(prom.NewHistogram(_metricSeconds)),
      metrics.WithRequests(prom.NewCounter(_metricRequests)),
    ),
  ),
)

// http service
httpSrv := http.NewServer(
  http.Address(":8000"),
  http.Middleware(
    metrics.Server(
      metrics.WithSeconds(prom.NewHistogram(_metricSeconds)),
      metrics.WithRequests(prom.NewCounter(_metricRequests)),
    ),
  ),
)
httpSrv.Handle("/metrics", promhttp.Handler())

Client 中使用 metrics

// grpc client
conn, err := grpc.DialInsecure(
  context.Background(),
  grpc.WithEndpoint("127.0.0.1:9000"),
  grpc.WithMiddleware(
    metrics.Client(
      metrics.WithSeconds(prom.NewHistogram(_metricSeconds)),
      metrics.WithRequests(prom.NewCounter(_metricRequests)),
    ),
  ),
)

// http client
conn, err := http.NewClient(
  context.Background(),
  http.WithEndpoint("127.0.0.1:8000"),
  http.WithMiddleware(
    metrics.Client(
      metrics.WithSeconds(prom.NewHistogram(_metricSeconds)),
      metrics.WithRequests(prom.NewCounter(_metricRequests)),
    ),
  ),
)

使用方式 (kratos >= 2.8.0)

kratos 从 v2.8.0 开始使用 otel.Metrics，需要用以下方法 export 数据到 prometheus。

使用 prometheus

import (
  "github.com/go-kratos/kratos/v2/middleware/metrics"
  "go.opentelemetry.io/otel/exporters/prometheus"
  "go.opentelemetry.io/otel/metric"
  sdkmetric "go.opentelemetry.io/otel/sdk/metric"
)

// Detailed reference https://github.com/go-kratos/examples/tree/main/metrics
func init() {
  exporter, err := prometheus.New()
  if err != nil {
    panic(err)
  }
  provider := sdkmetric.NewMeterProvider(sdkmetric.WithReader(exporter))
  meter := provider.Meter(Name)

  _metricRequests, err = metrics.DefaultRequestsCounter(meter, metrics.DefaultServerRequestsCounterName)
  if err != nil {
    panic(err)
  }

  _metricSeconds, err = metrics.DefaultSecondsHistogram(meter, metrics.DefaultServerSecondsHistogramName)
  if err != nil {
    panic(err)
  }
}

Server 中使用 metrics

import (
  "github.com/prometheus/client_golang/prometheus/promhttp"
)

// grpc service
grpcSrv := grpc.NewServer(
  grpc.Address(":9000"),
  grpc.Middleware(
    metrics.Server(
      metrics.WithSeconds(_metricSeconds),
      metrics.WithRequests(_metricRequests),
    ),
  ),
)

// http service
httpSrv := http.NewServer(
  http.Address(":8000"),
  http.Middleware(
    metrics.Server(
      metrics.WithSeconds(_metricSeconds),
      metrics.WithRequests(_metricRequests),
    ),
  ),
)
httpSrv.Handle("/metrics", promhttp.Handler())

Client 中使用 metrics

// grpc client
conn, err := grpc.DialInsecure(
  context.Background(),
  grpc.WithEndpoint("127.0.0.1:9000"),
  grpc.WithMiddleware(
    metrics.Client(
      metrics.WithSeconds(_metricSeconds),
      metrics.WithRequests(_metricRequests),
    ),
  ),
)

// http client
conn, err := http.NewClient(
  context.Background(),
  http.WithEndpoint("127.0.0.1:8000"),
  http.WithMiddleware(
    metrics.Client(
      metrics.WithSeconds(_metricSeconds),
      metrics.WithRequests(_metricRequests),
    ),
  ),
)

References

• https://prometheus.io/docs/concepts/metric_types/
• https://github.com/go-kratos/examples/tree/main/metrics
• https://pkg.go.dev/go.opentelemetry.io/otel/exporters/prometheus