middleware

type PrometheusMetrics ¶

type PrometheusMetrics struct {
	// contains filtered or unexported fields
}

PrometheusMetrics implements a net/http middleware that records HTTP request statistics as Prometheus metrics

deprecated: moved to github.com/clambin/go-common/http/middleware

package main

import (
	"github.com/clambin/go-common/httpserver/middleware"
	"github.com/prometheus/client_golang/prometheus"
	"net/http"
)

func main() {
	handler := func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("Hello"))
	}

	// This will create the following metrics:
	//   foo_bar_http_requests_total
	//   foo_bar_http_requests_duration_seconds
	//
	// Both will have a label "handler" set to "example".
	// The duration metrics will be a Summary (i.e. the default)
	m := middleware.NewPrometheusMetrics(middleware.PrometheusMetricsOptions{
		Namespace:   "foo",
		Subsystem:   "bar",
		Application: "example",
	})
	prometheus.MustRegister(m)

	s := &http.Server{
		Addr:    ":8080",
		Handler: m.Handle(http.HandlerFunc(handler)),
	}

	_ = s.ListenAndServe()
}

Output:

func NewPrometheusMetrics(o PrometheusMetricsOptions) *PrometheusMetrics

m := NewPrometheusMetrics(options)
prometheus.MustRegister(m)

func (m *PrometheusMetrics) Collect(c chan<- prometheus.Metric)

func (m *PrometheusMetrics) Describe(descs chan<- *prometheus.Desc)

func (m *PrometheusMetrics) Handle(next http.Handler) http.Handler

type PrometheusMetricsDurationType ¶

type PrometheusMetricsDurationType int

PrometheusMetricsDurationType specifies the type of metrics to record for request duration. Use Summary if you are only interested in the average latency. Use Histogram if you want to use a histogram to measure a service level indicator (eg latency of 95% of all requests).

const (
	// Summary measures the average duration.
	Summary PrometheusMetricsDurationType = iota
	// Histogram measures the latency in buckets and can be used to calculate a service level indicator. PrometheusMetricsOptions.Buckets
	// specify the buckets to be used. If none are provided, prometheus.DefBuckets will be used.
	Histogram
)

type PrometheusMetricsOptions ¶

type PrometheusMetricsOptions struct {
	// Namespace is used as namespace to create the metrics' fully qualified name
	Namespace string
	// Subsystem is used as namespace to create the metrics' fully qualified name
	Subsystem string
	// Application will be added as a 'handler' label to all metrics
	Application string
	// MetricsType specifies if the duration metrics should be recorded as a Summary or a Histogram
	MetricsType PrometheusMetricsDurationType
	// Buckets specifies the buckets to use for a Histogram duration metric.
	// If left blank, prometheus.DefBuckets will be used
	Buckets []float64
}

PrometheusMetricsOptions configure the metrics to be captured by a PrometheusMetrics middleware.

type RequestLogFormatter ¶ added in v0.11.0

type RequestLogFormatter interface {
	FormatRequest(*http.Request, int, time.Duration) []slog.Attr
}

A RequestLogFormatter takes the HTTP request, the resulting HTTP status code and latency and formats the log entry.

var DefaultRequestLogFormatter RequestLogFormatter = &defaultRequestLogFormatter{}

type RequestLogFormatterFunc ¶ added in v0.11.0

type RequestLogFormatterFunc func(r *http.Request, statusCode int, latency time.Duration) []slog.Attr

The RequestLogFormatterFunc type is an adapter that allows an ordinary function to be used as a RequestLogFormatter.

func (f RequestLogFormatterFunc) FormatRequest(r *http.Request, statusCode int, latency time.Duration) []slog.Attr