prom

Prometheus Adapter for Contextualized Stats Tracker

This library provides context-driven stats tracker implementation.

Features

• Context-driven labels control.
• Zero allocation.
• A simple interface with variadic number of key-value pairs for labels.
• Easily mockable interface free from 3rd party dependencies.

Example

// Bring your own Prometheus registry.
registry := prometheus.NewRegistry()
tr := prom.Tracker{
    Registry: registry,
}

// Add custom Prometheus configuration where necessary.
tr.DeclareHistogram("my_latency_seconds", prometheus.HistogramOpts{
    Buckets: []float64{1e-4, 1e-3, 1e-2, 1e-1, 1, 10, 100},
})

ctx := context.Background()

// Add labels to context.
ctx = stats.AddKeysAndValues(ctx, "ctx-label", "ctx-value0")

// Override label values.
ctx = stats.AddKeysAndValues(ctx, "ctx-label", "ctx-value1")

// Collect stats with last mile labels.
tr.Add(ctx, "my_count", 1,
    "some-label", "some-value",
)

tr.Add(ctx, "my_latency_seconds", 1.23)

tr.Set(ctx, "temperature", 33.3)

Performance

Sample benchmark result with go1.16.

goos: darwin
goarch: amd64
pkg: github.com/bool64/stats/prom-stats
cpu: Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz

name             time/op
Tracker_Add-8    635ns ± 3%
RawPrometheus-8  472ns ± 2%

name             alloc/op
Tracker_Add-8    0.00B     
RawPrometheus-8   336B ± 0%

name             allocs/op
Tracker_Add-8     0.00     
RawPrometheus-8   2.00 ± 0%

Caveats

Prometheus client does not support metrics with same name and different label sets. If you add a label to context, make sure you have it in all cases, at least with an empty value "".

Versioning

This project adheres to Semantic Versioning.

Before version 1.0.0, breaking changes are tagged with MINOR bump, features and fixes are tagged with PATCH bump. After version 1.0.0, breaking changes are tagged with MAJOR bump.