ginprometheus

README

go-gin-prometheus

Gin Web Framework Prometheus metrics exporter

Installation

$ go get github.com/zsais/go-gin-prometheus

Usage

package main

import (
	"github.com/gin-gonic/gin"
	"github.com/zsais/go-gin-prometheus"
)

func main() {
	r := gin.New()

	p := ginprometheus.NewPrometheus("gin")
	p.Use(r)

	r.GET("/", func(c *gin.Context) {
		c.JSON(200, "Hello world!")
	})

	r.Run(":29090")
}

See the example.go file

Preserving a low cardinality for the request counter

The request counter (requests_total) has a url label which, although desirable, can become problematic in cases where your application uses templated routes expecting a great number of variations, as Prometheus explicitly recommends against metrics having high cardinality dimensions:

https://prometheus.io/docs/practices/naming/#labels

If you have for instance a /customer/:name templated route and you don't want to generate a time series for every possible customer name, you could supply this mapping function to the middleware:

package main

import (
	"github.com/gin-gonic/gin"
	"github.com/zsais/go-gin-prometheus"
)

func main() {
	r := gin.New()

	p := ginprometheus.NewPrometheus("gin")

	p.ReqCntURLLabelMappingFn = func(c *gin.Context) string {
		url := c.Request.URL.String()
		for _, p := range c.Params {
			if p.Key == "name" {
				url = strings.Replace(url, p.Value, ":name", 1)
				break
			}
		}
		return url
	}

	p.Use(r)

	r.GET("/", func(c *gin.Context) {
		c.JSON(200, "Hello world!")
	})

	r.Run(":29090")
}

which would map /customer/alice and /customer/bob to their template /customer/:name, and thus preserve a low cardinality for our metrics.

Documentation

Index

• func NewMetric(m *Metric, subsystem string) prometheus.Collector
• type Metric
• type Prometheus
  • func NewPrometheus(subsystem string, customMetricsList ...[]*Metric) *Prometheus
  • func (p *Prometheus) SetListenAddress(address string)
  • func (p *Prometheus) SetListenAddressWithRouter(listenAddress string, r *gin.Engine)
  • func (p *Prometheus) SetPushGateway(pushGatewayURL, metricsURL string, pushIntervalSeconds time.Duration)
  • func (p *Prometheus) SetPushGatewayJob(j string)
  • func (p *Prometheus) Use(e *gin.Engine)
  • func (p *Prometheus) UseWithAuth(e *gin.Engine, accounts gin.Accounts)
• type PrometheusPushGateway
• type RequestCounterURLLabelMappingFn

Functions

func NewMetric

func NewMetric(m *Metric, subsystem string) prometheus.Collector

NewMetric associates prometheus.Collector based on Metric.Type

Types

type Metric

type Metric struct {
	MetricCollector prometheus.Collector
	ID              string
	Name            string
	Description     string
	Type            string
	Args            []string
}

Metric is a definition for the name, description, type, ID, and prometheus.Collector type (i.e. CounterVec, Summary, etc) of each metric

type Prometheus

type Prometheus struct {
	Ppg PrometheusPushGateway

	MetricsList []*Metric
	MetricsPath string

	ReqCntURLLabelMappingFn RequestCounterURLLabelMappingFn

	// gin.Context string to use as a prometheus URL label
	URLLabelFromContext string
	// contains filtered or unexported fields
}

Prometheus contains the metrics gathered by the instance and its path

func NewPrometheus

func NewPrometheus(subsystem string, customMetricsList ...[]*Metric) *Prometheus

NewPrometheus generates a new set of metrics with a certain subsystem name

func (*Prometheus) SetListenAddress

func (p *Prometheus) SetListenAddress(address string)

SetListenAddress for exposing metrics on address. If not set, it will be exposed at the same address of the gin engine that is being used

func (*Prometheus) SetListenAddressWithRouter

func (p *Prometheus) SetListenAddressWithRouter(listenAddress string, r *gin.Engine)

SetListenAddressWithRouter for using a separate router to expose metrics. (this keeps things like GET /metrics out of your content's access log).

func (*Prometheus) SetPushGateway

func (p *Prometheus) SetPushGateway(pushGatewayURL, metricsURL string, pushIntervalSeconds time.Duration)

SetPushGateway sends metrics to a remote pushgateway exposed on pushGatewayURL every pushIntervalSeconds. Metrics are fetched from metricsURL

func (*Prometheus) SetPushGatewayJob

func (p *Prometheus) SetPushGatewayJob(j string)

SetPushGatewayJob job name, defaults to "gin"

func (*Prometheus) Use

func (p *Prometheus) Use(e *gin.Engine)

Use adds the middleware to a gin engine.

func (*Prometheus) UseWithAuth

func (p *Prometheus) UseWithAuth(e *gin.Engine, accounts gin.Accounts)

UseWithAuth adds the middleware to a gin engine with BasicAuth.

type PrometheusPushGateway

type PrometheusPushGateway struct {

	// Push interval in seconds
	PushIntervalSeconds time.Duration

	// Push Gateway URL in format http://domain:port
	// where JOBNAME can be any string of your choice
	PushGatewayURL string

	// Local metrics URL where metrics are fetched from, this could be ommited in the future
	// if implemented using prometheus common/expfmt instead
	MetricsURL string

	// pushgateway job name, defaults to "gin"
	Job string
}

PrometheusPushGateway contains the configuration for pushing to a Prometheus pushgateway (optional)

type RequestCounterURLLabelMappingFn

type RequestCounterURLLabelMappingFn func(c *gin.Context) string

RequestCounterURLLabelMappingFn is a function which can be supplied to the middleware to control the cardinality of the request counter's "url" label, which might be required in some contexts. For instance, if for a "/customer/:name" route you don't want to generate a time series for every possible customer name, you could use this function:

func(c *gin.Context) string {
	url := c.Request.URL.String()
	for _, p := range c.Params {
		if p.Key == "name" {
			url = strings.Replace(url, p.Value, ":name", 1)
			break
		}
	}
	return url
}

which would map "/customer/alice" and "/customer/bob" to their template "/customer/:name".