Promenade

A simplified, and slightly more opinionated Prometheus client API for Golang.

The goal is to encourage much greater metric use within a project without excessive lines of code, and with much of the configurability and flexibility of the official Prometheus client API tucked away.

Registration happens on first use. All metric names are normalised and (by default) reduced to lowercase.

Benchmarks are provided.

---

Examples

import (
    "fmt"

    promenade "github.com/poblish/promenade/api"
)

func main() {
    metrics := promenade.NewMetrics(promenade.MetricOpts{MetricNamePrefix: "prefix"})

    metrics.Counter("c").Inc() // Increment prefix_c

    // Increment {city:London} label for prefix_places
    metrics.CounterWithLabel("places", "city").IncLabel("London")

    // Increment {type:cat, breed:persian} labels for prefix_animals
    metrics.CounterWithLabels("animals", []string{"type", "breed"}).IncLabel("cat", "persian")

    // Gauges
    metrics.Gauge("g").SetValue(101)
    metrics.Gauge("g").Dec()

    // Increment {error_type:bad} label for prefix_errors
    metrics.Error("bad")

    // Histograms
    histograms(&metrics)
    histogram_buckets(&metrics)

    // Timers
    timedMethod(&metrics)

    // Tests
    testMethods(&metrics)
}

func histograms(metrics *promenade.PrometheusMetrics) {
    times := metrics.HistogramForResponseTime("latency")
    times.Update(0.03)
    times.Update(0.05)
}

func histogram_buckets(metrics *promenade.PrometheusMetrics) {
    ages := metrics.Histogram("population_by_age", []float64{18, 25, 25, 45, 55, 65})
    ages.Update(21)
    ages.Update(45)
    ages.Update(81)
}

func timedMethod(metrics *promenade.PrometheusMetrics) {
    defer metrics.Timer("calculate Pi")()  // Start the timer, observe on exit

    fmt.Println("Start doing it...")
    // ...
}

func testMethods(metrics *promenade.PrometheusMetrics) {
    metrics.TestHelper().Clear()   // reset; start with new registry
    metrics.TestHelper().Gather()  // gather all registered Collectors 
    metrics.TestHelper().MetricNames()
    // etc.
}