woj-server/internal/web/metrics/prometheus.go

package metrics

import (
	"git.0x7f.app/WOJ/woj-server/internal/e"
	"git.0x7f.app/WOJ/woj-server/internal/misc/config"
	"git.0x7f.app/WOJ/woj-server/internal/pkg/cast"
	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/samber/do"
)

var _ Service = (*service)(nil)

type Service interface {
	Record(method, url string, success bool, httpCode int, errCode e.Status, elapsed float64)
	SetLogPaths(paths []string)
	Handler() gin.HandlerFunc
	HealthCheck() error
}

func NewService(i *do.Injector) (Service, error) {
	srv := &service{}

	conf := do.MustInvoke[config.Service](i).GetConfig()
	srv.setup(conf.Metrics.Namespace, conf.Metrics.Subsystem)

	return srv, nil
}

type service struct {
	namespace string
	subsystem string

	counter *prometheus.CounterVec
	hist    *prometheus.HistogramVec

	logPaths []string
}

func (s *service) HealthCheck() error {
	return nil
}

func (s *service) setup(namespace string, subsystem string) {
	s.namespace = namespace
	s.subsystem = subsystem

	s.counter = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "requests_total",
			Help:      "Total number of requests",
		},
		[]string{"method", "url"},
	)

	s.hist = prometheus.NewHistogramVec(
		prometheus.HistogramOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "requests_details",
			Help:      "Details of each request",
			Buckets:   []float64{0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 25, 50, 100, 250, 500, 1000},
		},
		[]string{"method", "url", "success", "http_code", "err_code"},
	)

	prometheus.MustRegister(s.counter, s.hist)
}

func (s *service) Record(method, url string, success bool, httpCode int, errCode e.Status, elapsed float64) {
	s.counter.With(prometheus.Labels{
		"method": method,
		"url":    url,
	}).Inc()

	s.hist.With(prometheus.Labels{
		"method":    method,
		"url":       url,
		"success":   cast.ToString(success),
		"http_code": cast.ToString(httpCode),
		"err_code":  cast.ToString(errCode),
	}).Observe(elapsed)
}