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http.go
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http.go
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package metrics
import (
"net/http"
"strconv"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
type Option func(opt *stateOption)
func WithNamespace(namespace string) Option {
return func(opt *stateOption) {
opt.namespace = namespace
}
}
func WithRegistry(registry Registry) Option {
return func(opt *stateOption) {
opt.registry = registry
}
}
func newStateOption() *stateOption {
return &stateOption{
namespace: "",
subsystem: "http",
}
}
type stateOption struct {
namespace string
subsystem string
registry Registry
}
type Registry interface {
prometheus.Registerer
prometheus.Gatherer
}
type HttpState struct {
option *stateOption
requestsTotal *prometheus.CounterVec
inflightRequests *prometheus.GaugeVec
requestsDuration *prometheus.HistogramVec
requestSize *prometheus.HistogramVec
responseSize *prometheus.HistogramVec
}
func NewHttpState(opts ...Option) *HttpState {
option := newStateOption()
for _, opt := range opts {
opt(option)
}
state := &HttpState{
option: option,
requestsTotal: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: option.namespace,
Subsystem: option.subsystem,
Name: "requests_total",
Help: "Number of get requests.",
},
[]string{"method", "path", "code"},
),
inflightRequests: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: option.namespace,
Subsystem: option.subsystem,
Name: "inflight_requests",
Help: "Status of HTTP response.",
},
[]string{"method", "path"},
),
requestsDuration: prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: option.namespace,
Subsystem: option.subsystem,
Name: "requests_duration_seconds",
Help: "Duration of HTTP requests.",
},
[]string{"method", "path"},
),
requestSize: prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: option.namespace,
Subsystem: option.subsystem,
Name: "request_size_bytes",
Help: "Size of HTTP requests.",
},
[]string{"method", "path"},
),
responseSize: prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: option.namespace,
Subsystem: option.subsystem,
Name: "response_size_bytes",
Help: "Size of HTTP responses.",
},
[]string{"method", "path"},
),
}
state.register()
return state
}
func (s *HttpState) register() {
collector := []prometheus.Collector{
s.requestsTotal,
s.inflightRequests,
s.requestsDuration,
s.requestSize,
s.responseSize,
}
registerer := prometheus.DefaultRegisterer
if s.option.registry != nil {
registerer = s.option.registry
}
for _, c := range collector {
registerer.MustRegister(c)
}
}
func (s *HttpState) Handler() http.Handler {
if s.option.registry != nil {
return promhttp.HandlerFor(s.option.registry, promhttp.HandlerOpts{})
}
return promhttp.Handler()
}
func (s *HttpState) WrapMetrics(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
start := time.Now()
path := r.URL.Path
method := r.Method
s.inflightRequests.WithLabelValues(method, path).Inc()
s.requestSize.WithLabelValues(method, path).Observe(float64(r.ContentLength))
delegate := &ResponseWriterDelegator{ResponseWriter: w}
defer func() {
duration := time.Since(start).Seconds()
code := codeToString(delegate.Status())
size := float64(delegate.ContentLength())
s.inflightRequests.WithLabelValues(method, path).Dec()
s.requestsTotal.WithLabelValues(method, path, code).Inc()
s.requestsDuration.WithLabelValues(method, path).Observe(duration)
s.responseSize.WithLabelValues(method, path).Observe(size)
}()
h.ServeHTTP(delegate, r)
})
}
var _ http.ResponseWriter = (*ResponseWriterDelegator)(nil)
// ResponseWriterDelegator interface wraps http.ResponseWriter to additionally record content-length, status-code, etc.
type ResponseWriterDelegator struct {
http.ResponseWriter
status int
written int64
wroteHeader bool
}
func (r *ResponseWriterDelegator) Unwrap() http.ResponseWriter {
return r.ResponseWriter
}
func (r *ResponseWriterDelegator) WriteHeader(code int) {
r.status = code
r.wroteHeader = true
r.ResponseWriter.WriteHeader(code)
}
func (r *ResponseWriterDelegator) Write(b []byte) (int, error) {
if !r.wroteHeader {
r.WriteHeader(http.StatusOK)
}
n, err := r.ResponseWriter.Write(b)
r.written += int64(n)
return n, err
}
func (r *ResponseWriterDelegator) Status() int {
return r.status
}
func (r *ResponseWriterDelegator) ContentLength() int {
return int(r.written)
}
// Small optimization over Itoa
func codeToString(s int) string {
switch s {
case 100:
return "100"
case 101:
return "101"
case 200:
return "200"
case 201:
return "201"
case 202:
return "202"
case 203:
return "203"
case 204:
return "204"
case 205:
return "205"
case 206:
return "206"
case 300:
return "300"
case 301:
return "301"
case 302:
return "302"
case 304:
return "304"
case 305:
return "305"
case 307:
return "307"
case 400:
return "400"
case 401:
return "401"
case 402:
return "402"
case 403:
return "403"
case 404:
return "404"
case 405:
return "405"
case 406:
return "406"
case 407:
return "407"
case 408:
return "408"
case 409:
return "409"
case 410:
return "410"
case 411:
return "411"
case 412:
return "412"
case 413:
return "413"
case 414:
return "414"
case 415:
return "415"
case 416:
return "416"
case 417:
return "417"
case 418:
return "418"
case 500:
return "500"
case 501:
return "501"
case 502:
return "502"
case 503:
return "503"
case 504:
return "504"
case 505:
return "505"
case 428:
return "428"
case 429:
return "429"
case 431:
return "431"
case 511:
return "511"
default:
return strconv.Itoa(s)
}
}