prometheus.go

package isuhttp

import (
	"net/http"
	"regexp"
	"sync"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	"github.com/valyala/fasthttp"
)

const (
	prometheusNamespace = "isutools"
	prometheusSubsystem = "api"
)

const (
	KB float64 = 1 << (10 * (iota + 1))
	MB
	GB
	TB
)

var reqDurBuckets = prometheus.DefBuckets

var reqSzBuckets = []float64{1.0 * KB, 2.0 * KB, 5.0 * KB, 10.0 * KB, 100 * KB, 500 * KB, 1.0 * MB, 2.5 * MB, 5.0 * MB, 10.0 * MB}

var resSzBuckets = []float64{1.0 * KB, 2.0 * KB, 5.0 * KB, 10.0 * KB, 100 * KB, 500 * KB, 1.0 * MB, 2.5 * MB, 5.0 * MB, 10.0 * MB}

var reqCounterVec = promauto.NewCounterVec(prometheus.CounterOpts{
	Namespace: prometheusNamespace,
	Subsystem: prometheusSubsystem,
	Name:      "request_total",
}, []string{"code", "method", "host", "url"})

var reqDurHistogramVec = promauto.NewHistogramVec(prometheus.HistogramOpts{
	Namespace: prometheusNamespace,
	Subsystem: prometheusSubsystem,
	Name:      "request_duration_seconds",
	Buckets:   reqDurBuckets,
}, []string{"code", "method", "url"})

var resSizeHistogramVec = promauto.NewHistogramVec(prometheus.HistogramOpts{
	Namespace: prometheusNamespace,
	Subsystem: prometheusSubsystem,
	Name:      "response_size_bytes",
	Buckets:   resSzBuckets,
}, []string{"code", "method", "url"})

var reqSizeHistogramVec = promauto.NewHistogramVec(prometheus.HistogramOpts{
	Namespace: prometheusNamespace,
	Subsystem: prometheusSubsystem,
	Name:      "request_size_bytes",
	Buckets:   reqSzBuckets,
}, []string{"code", "method", "url"})

var flowCounterVec = promauto.NewCounterVec(prometheus.CounterOpts{
	Namespace: prometheusNamespace,
	Subsystem: prometheusSubsystem,
	Name:      "flow_total",
}, []string{"source_method", "source_path", "target_method", "target_path"})

// reqSize 大まかなリクエストサイズ
func reqSize(req *http.Request) float64 {
	size := 0.0
	if req.URL != nil {
		size += float64(len(req.URL.RawPath))
	}

	size += float64(len(req.Method))
	size += float64(len(req.Proto))
	for name, values := range req.Header {
		size += float64(len(name))
		for _, value := range values {
			size += float64(len(value))
		}
	}

	if req.ContentLength > 0 {
		size += float64(req.ContentLength)
	}

	return size
}

// fastHTTPReqSize 大まかなリクエストサイズ
func fastHTTPReqSize(req *fasthttp.Request) float64 {
	size := 0.0

	size += float64(len(req.Header.Method()))
	size += float64(len(req.URI().PathOriginal()))
	size += float64(len(req.Header.Protocol()))

	size += float64(len(req.Header.Header()))

	if req.Header.ContentLength() > 0 {
		size += float64(req.Header.ContentLength())
	}

	return size
}

var (
	filterCacheLocker = &sync.RWMutex{}
	filterCache       = make(map[string]string, 50)
	filterReList      = []struct {
		re *regexp.Regexp
		to string
	}{{
		// uuid
		re: regexp.MustCompile(`[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}`),
		to: "<uuid>",
	}, {
		// number
		re: regexp.MustCompile(`\d+`),
		to: "<number>",
	}}
)

var FilterFunc = func(path string) string {
	newPath, ok := func() (string, bool) {
		filterCacheLocker.RLock()
		defer filterCacheLocker.RUnlock()

		if v, ok := filterCache[path]; ok {
			return v, true
		}

		return "", false
	}()
	if ok {
		return newPath
	}

	for _, re := range filterReList {
		path = re.re.ReplaceAllString(path, re.to)
	}

	return path
}