golang-lib/web/metrics/main.go

package metrics

import (
	"strings"

	"github.com/gin-gonic/gin"

	// gin-prometheus
	"github.com/chenjiandongx/ginprom"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	// db metrics
	gormPrometheus "gorm.io/plugin/prometheus"

	"dev.sum7.eu/genofire/golang-lib/web"
)

var (
	// NAMESPACE of prometheus metrics
	NAMESPACE string = "service"
	// VERSION in prometheus metrics
	VERSION string = ""
	// UP function for healthy check in prometheus metrics
	UP func() bool = func() bool {
		return true
	}
)

// Register to WebService
func Register(r *gin.Engine, ws *web.Service) {
	r.Use(ginprom.PromMiddleware(&ginprom.PromOpts{
		EndpointLabelMappingFn: func(c *gin.Context) string {
			url := c.Request.URL.Path
			for _, p := range c.Params {
				url = strings.Replace(url, p.Value, ":"+p.Key, 1)
			}
			return url
		},
	}))

	prometheus.MustRegister(prometheus.NewGaugeFunc(
		prometheus.GaugeOpts{
			Namespace:   NAMESPACE,
			Name:        "up",
			Help:        "is current version of service running",
			ConstLabels: prometheus.Labels{"version": VERSION},
		},
		func() float64 {
			if UP() {
				return 1
			}
			return 0
		},
	))

	if ws.DB != nil {
		ws.DB.Use(gormPrometheus.New(gormPrometheus.Config{
			DBName:          NAMESPACE,
			RefreshInterval: 15,
		}))

	}

	r.GET("/metrics", ginprom.PromHandler(promhttp.Handler()))
}