forked from stefanprodan/podinfo
/
metrics.go
379 lines (332 loc) · 9.93 KB
/
metrics.go
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package api
import (
"bufio"
"fmt"
"io"
"net"
"net/http"
"regexp"
"strconv"
"strings"
"time"
"github.com/gorilla/mux"
"github.com/prometheus/client_golang/prometheus"
)
type PrometheusMiddleware struct {
Histogram *prometheus.HistogramVec
Counter *prometheus.CounterVec
}
func NewPrometheusMiddleware() *PrometheusMiddleware {
// used for monitoring and alerting (RED method)
histogram := prometheus.NewHistogramVec(prometheus.HistogramOpts{
Subsystem: "http",
Name: "request_duration_seconds",
Help: "Seconds spent serving HTTP requests.",
Buckets: prometheus.DefBuckets,
}, []string{"method", "path", "status"})
// used for horizontal pod auto-scaling (Kubernetes HPA v2)
counter := prometheus.NewCounterVec(
prometheus.CounterOpts{
Subsystem: "http",
Name: "requests_total",
Help: "The total number of HTTP requests.",
},
[]string{"status"},
)
prometheus.MustRegister(histogram)
prometheus.MustRegister(counter)
return &PrometheusMiddleware{
Histogram: histogram,
Counter: counter,
}
}
// Metrics godoc
// @Summary Prometheus metrics
// @Description returns HTTP requests duration and Go runtime metrics
// @Tags Kubernetes
// @Produce plain
// @Router /metrics [get]
// @Success 200 {string} string "OK"
func (p *PrometheusMiddleware) Handler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
begin := time.Now()
interceptor := &interceptor{ResponseWriter: w, statusCode: http.StatusOK}
path := p.getRouteName(r)
next.ServeHTTP(interceptor.wrappedResponseWriter(), r)
var (
status = strconv.Itoa(interceptor.statusCode)
took = time.Since(begin)
)
p.Histogram.WithLabelValues(r.Method, path, status).Observe(took.Seconds())
p.Counter.WithLabelValues(status).Inc()
})
}
// converts gorilla mux routes from '/api/delay/{wait}' to 'api_delay_wait'
func (p *PrometheusMiddleware) getRouteName(r *http.Request) string {
if mux.CurrentRoute(r) != nil {
if name := mux.CurrentRoute(r).GetName(); len(name) > 0 {
return urlToLabel(name)
}
if path, err := mux.CurrentRoute(r).GetPathTemplate(); err == nil {
if len(path) > 0 {
return urlToLabel(path)
}
}
}
return urlToLabel(r.RequestURI)
}
var invalidChars = regexp.MustCompile(`[^a-zA-Z0-9]+`)
// converts a URL path to a string compatible with Prometheus label value.
func urlToLabel(path string) string {
result := invalidChars.ReplaceAllString(path, "_")
result = strings.ToLower(strings.Trim(result, "_"))
if result == "" {
result = "root"
}
return result
}
type interceptor struct {
http.ResponseWriter
statusCode int
recorded bool
}
func (i *interceptor) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hj, ok := i.ResponseWriter.(http.Hijacker)
if !ok {
return nil, nil, fmt.Errorf("interceptor: can't cast parent ResponseWriter to Hijacker")
}
return hj.Hijack()
}
func (i *interceptor) WriteHeader(code int) {
if !i.recorded {
i.statusCode = code
i.recorded = true
}
i.ResponseWriter.WriteHeader(code)
}
// Returns a wrapped http.ResponseWriter that implements the same optional interfaces
// that the underlying ResponseWriter has.
// Handle every possible combination so that code that checks for the existence of each
// optional interface functions properly.
// Based on https://github.com/felixge/httpsnoop/blob/eadd4fad6aac69ae62379194fe0219f3dbc80fd3/wrap_generated_gteq_1.8.go#L66
func (i *interceptor) wrappedResponseWriter() http.ResponseWriter {
closeNotifier, isCloseNotifier := i.ResponseWriter.(http.CloseNotifier)
flush, isFlusher := i.ResponseWriter.(http.Flusher)
hijack, isHijacker := i.ResponseWriter.(http.Hijacker)
push, isPusher := i.ResponseWriter.(http.Pusher)
readFrom, isReaderFrom := i.ResponseWriter.(io.ReaderFrom)
switch {
case !isCloseNotifier && !isFlusher && !isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
}{i}
case isCloseNotifier && !isFlusher && !isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
}{i, closeNotifier}
case !isCloseNotifier && isFlusher && !isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
}{i, flush}
case !isCloseNotifier && !isFlusher && isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Hijacker
}{i, hijack}
case !isCloseNotifier && !isFlusher && !isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Pusher
}{i, push}
case !isCloseNotifier && !isFlusher && !isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
io.ReaderFrom
}{i, readFrom}
case isCloseNotifier && isFlusher && !isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
}{i, closeNotifier, flush}
case isCloseNotifier && !isFlusher && isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Hijacker
}{i, closeNotifier, hijack}
case isCloseNotifier && !isFlusher && !isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Pusher
}{i, closeNotifier, push}
case isCloseNotifier && !isFlusher && !isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
io.ReaderFrom
}{i, closeNotifier, readFrom}
case !isCloseNotifier && isFlusher && isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Hijacker
}{i, flush, hijack}
case !isCloseNotifier && isFlusher && !isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Pusher
}{i, flush, push}
case !isCloseNotifier && isFlusher && !isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
io.ReaderFrom
}{i, flush, readFrom}
case !isCloseNotifier && !isFlusher && isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Hijacker
http.Pusher
}{i, hijack, push}
case !isCloseNotifier && !isFlusher && isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Hijacker
io.ReaderFrom
}{i, hijack, readFrom}
case !isCloseNotifier && !isFlusher && !isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Pusher
io.ReaderFrom
}{i, push, readFrom}
case isCloseNotifier && isFlusher && isHijacker && !isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Hijacker
}{i, closeNotifier, flush, hijack}
case isCloseNotifier && isFlusher && !isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Pusher
}{i, closeNotifier, flush, push}
case isCloseNotifier && isFlusher && !isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
io.ReaderFrom
}{i, closeNotifier, flush, readFrom}
case isCloseNotifier && !isFlusher && isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Hijacker
http.Pusher
}{i, closeNotifier, hijack, push}
case isCloseNotifier && !isFlusher && isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Hijacker
io.ReaderFrom
}{i, closeNotifier, hijack, readFrom}
case isCloseNotifier && !isFlusher && !isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Pusher
io.ReaderFrom
}{i, closeNotifier, push, readFrom}
case !isCloseNotifier && isFlusher && isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Hijacker
http.Pusher
}{i, flush, hijack, push}
case !isCloseNotifier && isFlusher && isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Hijacker
io.ReaderFrom
}{i, flush, hijack, readFrom}
case !isCloseNotifier && isFlusher && !isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Pusher
io.ReaderFrom
}{i, flush, push, readFrom}
case !isCloseNotifier && !isFlusher && isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Hijacker
http.Pusher
io.ReaderFrom
}{i, hijack, push, readFrom}
case isCloseNotifier && isFlusher && isHijacker && isPusher && !isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Hijacker
http.Pusher
}{i, closeNotifier, flush, hijack, push}
case isCloseNotifier && isFlusher && isHijacker && !isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Hijacker
io.ReaderFrom
}{i, closeNotifier, flush, hijack, readFrom}
case isCloseNotifier && isFlusher && !isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Pusher
io.ReaderFrom
}{i, closeNotifier, flush, push, readFrom}
case isCloseNotifier && !isFlusher && isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Hijacker
http.Pusher
io.ReaderFrom
}{i, closeNotifier, hijack, push, readFrom}
case !isCloseNotifier && isFlusher && isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.Flusher
http.Hijacker
http.Pusher
io.ReaderFrom
}{i, flush, hijack, push, readFrom}
case isCloseNotifier && isFlusher && isHijacker && isPusher && isReaderFrom:
return struct {
http.ResponseWriter
http.CloseNotifier
http.Flusher
http.Hijacker
http.Pusher
io.ReaderFrom
}{i, closeNotifier, flush, hijack, push, readFrom}
default:
return struct {
http.ResponseWriter
}{i}
}
}