Gin Web Framework Prometheus metrics exporter
$ go get github.com/zoftdev/go-gin-prometheus
package main
import (
"github.com/gin-gonic/gin"
"github.com/zoftdev/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
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/zoftdev/go-gin-prometheus"
)
func main() {
r := gin.New()
p := ginprometheus.NewPrometheus("gin")
p.ReqCntURLLabelMappingFn = func(c *gin.Context) string {
url := c.Request.URL.Path
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.
if you use gin_request_* to report healthy, and want to override code field e.g.
gin_request_duration_seconds_bucket{code="2002",method="POST",url="/api/v1/updateStatus",le="5"} 1
use StatusOverrideFromContext
p := ginprometheus.NewPrometheus("gin")
p.StatusOverrideFromContext = append(p.StatusOverrideFromContext, "code")
p.StatusOverrideFromContext = append(p.StatusOverrideFromContext, "mycode")
and set in gin's context
r.GET("/", func(c *gin.Context) {
c.Set("code", "888")
c.JSON(200, "Hello world!")
})