handler.go

Documentation: github.com/docker/go-metrics

     1  package metrics
     2  
     3  import (
     4  	"net/http"
     5  
     6  	"github.com/prometheus/client_golang/prometheus"
     7  	"github.com/prometheus/client_golang/prometheus/promhttp"
     8  )
     9  
    10  // HTTPHandlerOpts describes a set of configurable options of http metrics
    11  type HTTPHandlerOpts struct {
    12  	DurationBuckets     []float64
    13  	RequestSizeBuckets  []float64
    14  	ResponseSizeBuckets []float64
    15  }
    16  
    17  const (
    18  	InstrumentHandlerResponseSize = iota
    19  	InstrumentHandlerRequestSize
    20  	InstrumentHandlerDuration
    21  	InstrumentHandlerCounter
    22  	InstrumentHandlerInFlight
    23  )
    24  
    25  type HTTPMetric struct {
    26  	prometheus.Collector
    27  	handlerType int
    28  }
    29  
    30  var (
    31  	defaultDurationBuckets     = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10, 25, 60}
    32  	defaultRequestSizeBuckets  = prometheus.ExponentialBuckets(1024, 2, 22) //1K to 4G
    33  	defaultResponseSizeBuckets = defaultRequestSizeBuckets
    34  )
    35  
    36  // Handler returns the global http.Handler that provides the prometheus
    37  // metrics format on GET requests. This handler is no longer instrumented.
    38  func Handler() http.Handler {
    39  	return promhttp.Handler()
    40  }
    41  
    42  func InstrumentHandler(metrics []*HTTPMetric, handler http.Handler) http.HandlerFunc {
    43  	return InstrumentHandlerFunc(metrics, handler.ServeHTTP)
    44  }
    45  
    46  func InstrumentHandlerFunc(metrics []*HTTPMetric, handlerFunc http.HandlerFunc) http.HandlerFunc {
    47  	var handler http.Handler
    48  	handler = http.HandlerFunc(handlerFunc)
    49  	for _, metric := range metrics {
    50  		switch metric.handlerType {
    51  		case InstrumentHandlerResponseSize:
    52  			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
    53  				handler = promhttp.InstrumentHandlerResponseSize(collector, handler)
    54  			}
    55  		case InstrumentHandlerRequestSize:
    56  			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
    57  				handler = promhttp.InstrumentHandlerRequestSize(collector, handler)
    58  			}
    59  		case InstrumentHandlerDuration:
    60  			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
    61  				handler = promhttp.InstrumentHandlerDuration(collector, handler)
    62  			}
    63  		case InstrumentHandlerCounter:
    64  			if collector, ok := metric.Collector.(*prometheus.CounterVec); ok {
    65  				handler = promhttp.InstrumentHandlerCounter(collector, handler)
    66  			}
    67  		case InstrumentHandlerInFlight:
    68  			if collector, ok := metric.Collector.(prometheus.Gauge); ok {
    69  				handler = promhttp.InstrumentHandlerInFlight(collector, handler)
    70  			}
    71  		}
    72  	}
    73  	return handler.ServeHTTP
    74  }
    75
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