[Go] Prometheus + gin router

router.go

import 	(
	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

// ... 
{
	r := gin.New()
	r.GET("/metrics", func() gin.HandlerFunc {
		h := promhttp.Handler()
		return func(c *gin.Context) {
			h.ServeHTTP(c.Writer, c.Request)
		}
	}())
}
// ...