Prometheus Implementation

[nicholasanthonys]

How to implement prometheus counter on echo ? should i use this package https://github.com/prometheus/client_golang ? or is it enough to use echo package : github.com/labstack/echo-contrib/prometheus ?

[aldas]

https://github.com/labstack/echo-contrib/blob/master/prometheus/prometheus.go registers middleware for http server and exposes prometheus metrics through /metrics route.

You can use it with your own custom metrics.

For example:

import (
	promMW "github.com/labstack/echo-contrib/prometheus"
	"github.com/labstack/echo/v4"
	"github.com/labstack/gommon/log"
	"github.com/prometheus/client_golang/prometheus"
	"net/http"
)

func main() {
	e := echo.New()
	p := promMW.NewPrometheus("echo", nil)

	myCounter := prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        "my_handler_executions",
		Help:        "Counts executions of my handler function.",
		ConstLabels: prometheus.Labels{"version": "1234"},
	})
	if err := prometheus.Register(myCounter); err != nil {
		log.Fatal(err)
	}

	e.GET("/", func(c echo.Context) error {
		myCounter.Inc()
		return c.JSON(http.StatusOK, "OK")
	})

	p.Use(e) // Enable metrics middleware and register route to expose metrics

	if err := e.Start("localhost:8080"); err != http.ErrServerClosed {
		log.Fatal(err)
	}
}

And output:

x@x:~/code$ curl http://localhost:8080
"OK"
x@x:~/code$ curl http://localhost:8080
"OK"
x@x:~/code$ curl http://localhost:8080/metrics
# HELP echo_request_duration_seconds The HTTP request latencies in seconds.
# TYPE echo_request_duration_seconds histogram
echo_request_duration_seconds_bucket{code="200",method="GET",url="/",le="0.005"} 2
echo_request_duration_seconds_bucket{code="200",method="GET",url="/",le="0.01"} 2
...
...
# HELP my_handler_executions Counts executions of my handler functions.
# TYPE my_handler_executions gauge
my_handler_executions{version="1234"} 2
...
...
...

[nicholasanthonys]

Thank you