diff --git a/README.md b/README.md index af24551..d3cb8c1 100644 --- a/README.md +++ b/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. diff --git a/middleware.go b/middleware.go index e65c68b..bcd28a7 100644 --- a/middleware.go +++ b/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() }, }