metrics/README.md

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# metrics - lightweight package for exporting metrics in Prometheus format


### Features

* Lightweight. Has minimal number of third-party dependencies and all these deps are small.
  See [this article](https://medium.com/@valyala/stripping-dependency-bloat-in-victoriametrics-docker-image-983fb5912b0d) for details.
* Easy to use. See the [API docs](http://godoc.org/github.com/VictoriaMetrics/metrics).
* Fast.


### Limitations

* It doesn't implement advanced functionality from [github.com/prometheus/client_golang/prometheus](https://godoc.org/github.com/prometheus/client_golang/prometheus).


### Usage

```go
import "github.com/VictoriaMetrics/metrics"

// Register various time series.
// Time series name may contain labels in Prometheus format - see below.
var (
	// Register counter without labels.
	requestsTotal = metrics.NewCounter("requests_total")

	// Register summary with a single label.
	requestDuration = metrics.NewSummary(`requests_duration_seconds{handler="/my/super/handler"}`)

	// Register gauge with two labels.
	queueSize = metrics.NewGauge(`queue_size{queue="foobar",topic="baz"}`, func() float64 {
		return float64(foobarQueue.Len())
	})
)

// ...
func requestHandler() {
	startTime := time.Now()
	// ...
	requestsTotal.Inc()
	requestDuration.UpdateDuration(startTime)
}
// ...

// `/metrics` handler for exposing the registered metrics.
http.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
	metrics.WritePrometheus(w, true)
})
```

See [docs](http://godoc.org/github.com/VictoriaMetrics/metrics) for more info.


### Users

* `Metrics` has been extracted from [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics) sources.
  See [this article](https://medium.com/devopslinks/victoriametrics-creating-the-best-remote-storage-for-prometheus-5d92d66787ac)
  for more info about `VictoriaMetrics`.