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), ), ) }