use gin.Context.FullPath by default

Author: Sniper91

README.md

@@ -32,55 +32,3 @@ func main() {
 ```
 
 See the [example.go file](https://github.com/zsais/go-gin-prometheus/blob/master/example/example.go)
-
-## 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:
-
-```go
-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.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.

middleware.go

@@ -17,6 +17,7 @@ import (
 var defaultMetricPath = "/metrics"
 
 // Standard default metrics
+//
 //	counter, counter_vec, gauge, gauge_vec,
 //	histogram, histogram_vec, summary, summary_vec
 var reqCnt = &Metric{
@@ -56,21 +57,6 @@ var standardMetrics = []*Metric{
 /*
 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.Path
-	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".
 */
 type RequestCounterURLLabelMappingFn func(c *gin.Context) string
 
@@ -140,7 +126,9 @@ func NewPrometheus(subsystem string, customMetricsList ...[]*Metric) *Prometheus
 		MetricsList: metricsList,
 		MetricsPath: defaultMetricPath,
 		ReqCntURLLabelMappingFn: func(c *gin.Context) string {
-			return c.Request.URL.Path // i.e. by default do nothing, i.e. return URL as is
+			// return route full path
+			// map "/customer/alice" and "/customer/bob" to their template "/customer/:name"
+			return c.FullPath()
 		},
 	}