A Go library for converting OpenTelemetry Protocol (OTLP) metric and attribute names to Prometheus-compliant formats. This is an internal library for both Prometheus and Open Telemetry, without any stability guarantees for external usage.

Part of the Prometheus ecosystem, following the OpenTelemetry to Prometheus compatibility specification.

Features

Metric Name and Label Translation: Convert OTLP metric names and attributes to Prometheus-compliant format
Unit Handling: Translate OTLP units to Prometheus unit conventions
Type-Aware Suffixes: Optionally append _total, _ratio based on metric type
Namespace Support: Add configurable namespace prefixes
UTF-8 Support: Choose between Prometheus legacy scheme compliant metric/label names ([a-zA-Z0-9:_]) or untranslated metric/label names
Translation Strategy Configuration: Select a translation strategy with a standard set of strings.

Installation

go get github.com/prometheus/otlptranslator

Quick Start

package main

import (
    "fmt"
    "github.com/prometheus/otlptranslator"
)

func main() {
    // Create a metric namer using traditional Prometheus name translation, with suffixes added and UTF-8 disallowed.
    strategy := otlptranslator.UnderscoreEscapingWithSuffixes
    namer := otlptranslator.NewMetricNamer("myapp", strategy)

    // Translate OTLP metric to Prometheus format
    metric := otlptranslator.Metric{
        Name: "http.server.request.duration",
        Unit: "s",
        Type: otlptranslator.MetricTypeHistogram,
    }
    fmt.Println(namer.Build(metric)) // Output: myapp_http_server_request_duration_seconds

    // Translate label names
    labelNamer := otlptranslator.LabelNamer{UTF8Allowed: false}
    fmt.Println(labelNamer.Build("http.method")) // Output: http_method
}

Usage Examples

Metric Name Translation

namer := otlptranslator.MetricNamer{WithMetricSuffixes: true, UTF8Allowed: false}

// Counter gets _total suffix
counter := otlptranslator.Metric{
    Name: "requests.count", Unit: "1", Type: otlptranslator.MetricTypeMonotonicCounter,
}
fmt.Println(namer.Build(counter)) // requests_count_total

// Gauge with unit conversion
gauge := otlptranslator.Metric{
    Name: "memory.usage", Unit: "By", Type: otlptranslator.MetricTypeGauge,
}
fmt.Println(namer.Build(gauge)) // memory_usage_bytes

// Dimensionless gauge gets _ratio suffix
ratio := otlptranslator.Metric{
    Name: "cpu.utilization", Unit: "1", Type: otlptranslator.MetricTypeGauge,
}
fmt.Println(namer.Build(ratio)) // cpu_utilization_ratio

Label Translation

labelNamer := otlptranslator.LabelNamer{UTF8Allowed: false}

labelNamer.Build("http.method")           // http_method
labelNamer.Build("123invalid")            // key_123invalid
labelNamer.Build("_private")              // key_private
labelNamer.Build("__reserved__")          // __reserved__ (preserved)
labelNamer.Build("label@with$symbols")    // label_with_symbols

Unit Translation

unitNamer := otlptranslator.UnitNamer{UTF8Allowed: false}

unitNamer.Build("s")           // seconds
unitNamer.Build("By")          // bytes
unitNamer.Build("requests/s")  // requests_per_second
unitNamer.Build("1")           // "" (dimensionless)

Configuration Options

// Prometheus-compliant mode - supports [a-zA-Z0-9:_]
compliantNamer := otlptranslator.MetricNamer{UTF8Allowed: false, WithMetricSuffixes: true}

// Transparent pass-through mode, aka "NoTranslation"
utf8Namer := otlptranslator.MetricNamer{UTF8Allowed: true, WithMetricSuffixes: false}
utf8Namer = otlptranslator.NewMetricNamer("", otlpTranslator.NoTranslation)

// With namespace and suffixes
productionNamer := otlptranslator.MetricNamer{
    Namespace:          "myservice",
    WithMetricSuffixes: true,
    UTF8Allowed:        false,
}

License

Licensed under the Apache License 2.0 - see the LICENSE file for details.