status-im/status-go

package metrics

import (
    "fmt"
    "net/http"
    "time"

    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/metrics"
    gethprom "github.com/ethereum/go-ethereum/metrics/prometheus"

    prom "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

// Server runs and controls a HTTP pprof interface.
type Server struct {
    server *http.Server
}

func NewMetricsServer(port int, r metrics.Registry) *Server {
    mux := http.NewServeMux()
    mux.Handle("/health", healthHandler())
    mux.Handle("/metrics", Handler(r))
    p := Server{
        server: &http.Server{
            Addr:              fmt.Sprintf(":%d", port),
            ReadHeaderTimeout: 5 * time.Second,
            Handler:           mux,
        },
    }
    return &p
}

func healthHandler() http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        _, err := w.Write([]byte("OK"))
        if err != nil {
            log.Error("health handler error", "err", err)
        }
    })
}

func Handler(reg metrics.Registry) http.Handler {
    // we disable compression because geth doesn't support it
    opts := promhttp.HandlerOpts{DisableCompression: true}
    // we are combining handlers to avoid having 2 endpoints
    statusMetrics := promhttp.HandlerFor(prom.DefaultGatherer, opts) // our metrics
    gethMetrics := gethprom.Handler(reg)                             // geth metrics
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        statusMetrics.ServeHTTP(w, r)
        gethMetrics.ServeHTTP(w, r)
    })
}

// Listen starts the HTTP server in the background.
func (p *Server) Listen() {
    log.Info("metrics server stopped", "err", p.server.ListenAndServe())
}