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package middleware
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
var (
requestCounter = prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "handler_requests_total",
Help: "Total number of request/responses by HTTP status code.",
}, []string{"handler", "code"})
requestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Name: "handler_request_duration",
Help: "Handler request duration.",
}, []string{"handler", "method"})
requestInFlight = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Name: "handler_requests_in_flight",
Help: "Current number of requests being served.",
}, []string{"handler"})
)
func init() {
_ = prometheus.Register(requestCounter)
_ = prometheus.Register(requestDuration)
_ = prometheus.Register(requestInFlight)
}
// Metrics captures request duration, request count and in-flight request count
// metrics for HTTP handlers. The family field is used to discriminate handlers.
func Metrics(family string, next http.Handler) http.Handler {
return promhttp.InstrumentHandlerDuration(
requestDuration.MustCurryWith(prometheus.Labels{"handler": family}),
promhttp.InstrumentHandlerCounter(requestCounter.MustCurryWith(prometheus.Labels{"handler": family}),
promhttp.InstrumentHandlerInFlight(requestInFlight.With(prometheus.Labels{"handler": family}), next),
),
)
}
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