Prometheus

note

Echo community contribution

Prometheus middleware generates metrics for HTTP requests.

https://github.com/labstack/echo-contrib/blob/master/echoprometheus/prometheus.go

Usage

Add needed module go get -u github.com/labstack/echo-contrib

Add Prometheus middleware and metrics serving route

e := echo.New()
e.Use(echoprometheus.NewMiddleware("myapp"))// adds middleware to gather metrics
e.GET("/metrics", echoprometheus.NewHandler())// adds route to serve gathered metrics

Examples

Serve metric from the same server as where metrics is gathered

package main

import(
"net/http"

"github.com/labstack/echo-contrib/echoprometheus"
"github.com/labstack/echo/v5"
)

funcmain(){
	e := echo.New()

	e.Use(echoprometheus.NewMiddleware("myapp"))// adds middleware to gather metrics
	e.GET("/metrics", echoprometheus.NewHandler())// adds route to serve gathered metrics

	e.GET("/hello",func(c *echo.Context)error{
return c.String(http.StatusOK,"hello")
})

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

Serve metrics on a separate port

funcmain(){
	e := echo.New()// this Echo instance will serve route on port 8080
	e.Use(echoprometheus.NewMiddleware("myapp"))// adds middleware to gather metrics

gofunc(){
		metrics := echo.New()// this Echo will run on separate port 8081
		metrics.GET("/metrics", echoprometheus.NewHandler())// adds route to serve gathered metrics
if err := metrics.Start(":8081"); err !=nil{
			e.Logger.Error("failed to start metrics server","error", err)
}
}()

	e.GET("/hello",func(c *echo.Context)error{
return c.String(http.StatusOK,"hello")
})

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

Sample output (for first example)

curl http://localhost:8080/metrics

# HELP echo_request_duration_seconds The HTTP request latencies in seconds.
# TYPE echo_request_duration_seconds summary
echo_request_duration_seconds_sum 0.41086482
echo_request_duration_seconds_count 1
# HELP echo_request_size_bytes The HTTP request sizes in bytes.
# TYPE echo_request_size_bytes summary
echo_request_size_bytes_sum 56
echo_request_size_bytes_count 1
# HELP echo_requests_total How many HTTP requests processed, partitioned by status code and HTTP method.
# TYPE echo_requests_total counter
echo_requests_total{code="200",host="localhost:8080",method="GET",url="/"} 1
# HELP echo_response_size_bytes The HTTP response sizes in bytes.
# TYPE echo_response_size_bytes summary
echo_response_size_bytes_sum 61
echo_response_size_bytes_count 1
...

Custom Configuration

Serving custom Prometheus Metrics

Usage

Using custom metrics with Prometheus default registry:

package main

import(
"log"

"github.com/labstack/echo-contrib/echoprometheus"
"github.com/labstack/echo/v5"
"github.com/prometheus/client_golang/prometheus"
)

funcmain(){
	e := echo.New()// this Echo instance will serve route on port 8080

	customCounter := prometheus.NewCounter(// create new counter metric. This is replacement for `prometheus.Metric` struct
		prometheus.CounterOpts{
			Name:"custom_requests_total",
			Help:"How many HTTP requests processed, partitioned by status code and HTTP method.",
},
)
if err := prometheus.Register(customCounter); err !=nil{// register your new counter metric with default metrics registry
		log.Fatal(err)
}

	e.Use(echoprometheus.NewMiddlewareWithConfig(echoprometheus.MiddlewareConfig{
		AfterNext:func(c *echo.Context, err error){
			customCounter.Inc()// use our custom metric in middleware. after every request increment the counter
},
}))
	e.GET("/metrics", echoprometheus.NewHandler())// register route for getting gathered metrics

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

or create your own registry and register custom metrics with that:

package main

import(
"log"

"github.com/labstack/echo-contrib/echoprometheus"
"github.com/labstack/echo/v5"
"github.com/prometheus/client_golang/prometheus"
)

funcmain(){
	e := echo.New()// this Echo instance will serve route on port 8080

	customRegistry := prometheus.NewRegistry()// create custom registry for your custom metrics
	customCounter := prometheus.NewCounter(// create new counter metric. This is replacement for `prometheus.Metric` struct
		prometheus.CounterOpts{
			Name:"custom_requests_total",
			Help:"How many HTTP requests processed, partitioned by status code and HTTP method.",
},
)
if err := customRegistry.Register(customCounter); err !=nil{// register your new counter metric with metrics registry
		log.Fatal(err)
}

	e.Use(echoprometheus.NewMiddlewareWithConfig(echoprometheus.MiddlewareConfig{
		AfterNext:func(c *echo.Context, err error){
			customCounter.Inc()// use our custom metric in middleware. after every request increment the counter
},
		Registerer: customRegistry,// use our custom registry instead of default Prometheus registry
}))
	e.GET("/metrics", echoprometheus.NewHandlerWithConfig(echoprometheus.HandlerConfig{Gatherer: customRegistry}))// register route for getting gathered metrics data from our custom Registry

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

Skipping URL(s)

Usage

A middleware skipper can be passed to avoid generating metrics to certain URL(s)

package main

import(
"net/http"
"strings"

"github.com/labstack/echo-contrib/echoprometheus"
"github.com/labstack/echo/v5"
)

funcmain(){
	e := echo.New()// this Echo instance will serve route on port 8080

	mwConfig := echoprometheus.MiddlewareConfig{
		Skipper:func(c *echo.Context)bool{
return strings.HasPrefix(c.Path(),"/testurl")
},// does not gather metrics metrics on routes starting with `/testurl`
}
	e.Use(echoprometheus.NewMiddlewareWithConfig(mwConfig))// adds middleware to gather metrics

	e.GET("/metrics", echoprometheus.NewHandler())// adds route to serve gathered metrics

	e.GET("/",func(c *echo.Context)error{
return c.String(http.StatusOK,"Hello, World!")
})

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

Complex Scenarios

Example: modify default echoprometheus metrics definitions

package main

import(
"net/http"

"github.com/labstack/echo-contrib/echoprometheus"
"github.com/labstack/echo/v5"
"github.com/prometheus/client_golang/prometheus"
)

funcmain(){
	e := echo.New()// this Echo instance will serve route on port 8080

	e.Use(echoprometheus.NewMiddlewareWithConfig(echoprometheus.MiddlewareConfig{
// labels of default metrics can be modified or added with `LabelFuncs` function
		LabelFuncs:map[string]echoprometheus.LabelValueFunc{
"scheme":func(c *echo.Context, err error)string{// additional custom label
return c.Scheme()
},
"host":func(c *echo.Context, err error)string{// overrides default 'host' label value
return"y_"+ c.Request().Host
},
},
// The `echoprometheus` middleware registers the following metrics by default:
// - Histogram: request_duration_seconds
// - Histogram: response_size_bytes
// - Histogram: request_size_bytes
// - Counter: requests_total
// which can be modified with `HistogramOptsFunc` and `CounterOptsFunc` functions
		HistogramOptsFunc:func(opts prometheus.HistogramOpts) prometheus.HistogramOpts {
if opts.Name =="request_duration_seconds"{
				opts.Buckets =[]float64{1000.0,10_000.0,100_000.0,1_000_000.0}// 1KB ,10KB, 100KB, 1MB
}
return opts
},
		CounterOptsFunc:func(opts prometheus.CounterOpts) prometheus.CounterOpts {
if opts.Name =="requests_total"{
				opts.ConstLabels = prometheus.Labels{"my_const":"123"}
}
return opts
},
}))// adds middleware to gather metrics

	e.GET("/metrics", echoprometheus.NewHandler())// adds route to serve gathered metrics

	e.GET("/hello",func(c *echo.Context)error{
return c.String(http.StatusOK,"hello")
})

if err := e.Start(":8080"); err !=nil{
		e.Logger.Error("failed to start server","error", err)
}
}

Usage​

Examples​

Custom Configuration​

Serving custom Prometheus Metrics​

Skipping URL(s)​