harbor/src/server/middleware/metric/metric.go

package metric

import (
	"net/http"
	"strconv"
	"time"

	"github.com/goharbor/harbor/src/core/config"
	"github.com/goharbor/harbor/src/lib/metric"
)

func instrumentHandler(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		now, url, code := time.Now(), r.URL.EscapedPath(), "0"

		metric.TotalInFlightGauge.WithLabelValues(url).Inc()
		defer metric.TotalInFlightGauge.WithLabelValues(url).Dec()

		next.ServeHTTP(w, r)
		if r.Response != nil {
			code = strconv.Itoa(r.Response.StatusCode)
		}

		metric.TotalReqDurSummary.WithLabelValues(r.Method, url).Observe(time.Since(now).Seconds())
		metric.TotalReqCnt.WithLabelValues(r.Method, code, url).Inc()
	})
}

// Middleware returns a middleware for handling requests
func Middleware() func(http.Handler) http.Handler {
	if config.Metric().Enabled {
		return func(next http.Handler) http.Handler {
			return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
				next = instrumentHandler(next)
				next.ServeHTTP(rw, req)
			})
		}
	}
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
			next.ServeHTTP(rw, req)
		})
	}
}