go.opentelemetry.io/otel/metric v1.42.0: Float64Histogram

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify go.opentelemetry.io/otel/metric.Float64Histogram in pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/metric.Float64Histogram

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:7100aa6b08105e67d205ffc50840dec47d12d1e6b17fc98fa20a9221043825a5","contract":["Meter creates Float64Histogram with description and unit options","Float64Histogram configures explicit bucket boundaries for duration tracking","Float64Histogram records floating-point observations with contextual attributes","Float64Histogram executes without errors using standard MeterProvider"],"goal":"verify go.opentelemetry.io/otel/metric.Float64Histogram in pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/metric.Float64Histogram"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0","symbols":["go.opentelemetry.io/otel/metric.Float64Histogram"],"verifierAdapter":"golang@1"}

module sample

go 1.25.0

require (
	go.opentelemetry.io/otel v1.42.0
	go.opentelemetry.io/otel/metric v1.42.0
)

require github.com/cespare/xxhash/v2 v2.3.0 // indirect

github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
go.opentelemetry.io/otel v1.42.0 h1:lSQGzTgVR3+sgJDAU/7/ZMjN9Z+vUip7leaqBKy4sho=
go.opentelemetry.io/otel v1.42.0/go.mod h1:lJNsdRMxCUIWuMlVJWzecSMuNjE7dOYyWlqOXWkdqCc=
go.opentelemetry.io/otel/metric v1.42.0 h1:2jXG+3oZLNXEPfNmnpxKDeZsFI5o4J+nz6xUlaFdF/4=
go.opentelemetry.io/otel/metric v1.42.0/go.mod h1:RlUN/7vTU7Ao/diDkEpQpnz3/92J9ko05BIwxYa2SSI=
go.opentelemetry.io/otel/trace v1.42.0 h1:OUCgIPt+mzOnaUTpOQcBiM/PLQ/Op7oq6g4LenLmOYY=
go.opentelemetry.io/otel/trace v1.42.0/go.mod h1:f3K9S+IFqnumBkKhRJMeaZeNk9epyhnCmQh/EysQCdc=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package sample

import (
	"context"
	"fmt"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/metric"
	"go.opentelemetry.io/otel/metric/noop"
)

// RequestLatencyRecorder records request durations using Float64Histogram.
type RequestLatencyRecorder struct {
	meter             metric.Meter
	durationHistogram metric.Float64Histogram
}

// NewRequestLatencyRecorder creates a new RequestLatencyRecorder.
// If provider is nil, a no-op MeterProvider is used.
func NewRequestLatencyRecorder(provider metric.MeterProvider, meterName string) (*RequestLatencyRecorder, error) {
	if provider == nil {
		provider = noop.NewMeterProvider()
	}

	meter := provider.Meter(
		meterName,
		metric.WithInstrumentationVersion("v1.42.0"),
	)

	histogram, err := meter.Float64Histogram(
		"http.server.request.duration",
		metric.WithDescription("Measures the duration of inbound HTTP requests"),
		metric.WithUnit("s"),
		metric.WithExplicitBucketBoundaries(0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10),
	)
	if err != nil {
		return nil, fmt.Errorf("create Float64Histogram: %w", err)
	}

	return &RequestLatencyRecorder{
		meter:             meter,
		durationHistogram: histogram,
	}, nil
}

// RecordDuration records a request duration observation in seconds with HTTP route and status attributes.
func (r *RequestLatencyRecorder) RecordDuration(ctx context.Context, durationSec float64, route string, statusCode int) {
	r.durationHistogram.Record(
		ctx,
		durationSec,
		metric.WithAttributes(
			attribute.String("http.route", route),
			attribute.Int("http.response.status_code", statusCode),
		),
	)
}

// Histogram returns the underlying Float64Histogram instrument.
func (r *RequestLatencyRecorder) Histogram() metric.Float64Histogram {
	return r.durationHistogram
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/metric.Float64Histogram in pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/metric@v1.42.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/metric.Float64Histogram"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/metric"
	"go.opentelemetry.io/otel/metric/noop"
	"sample"
)

func main() {
	ctx := context.Background()

	// 1. Meter creates Float64Histogram with description and unit options
	mp := noop.NewMeterProvider()
	meter := mp.Meter("contract-test-meter", metric.WithInstrumentationVersion("v1.42.0"))

	hist, err := meter.Float64Histogram(
		"test.duration",
		metric.WithDescription("Duration of test operations"),
		metric.WithUnit("ms"),
	)
	if err != nil || hist == nil {
		fmt.Fprintf(os.Stderr, "failed to create Float64Histogram with description and unit: %v\n", err)
		os.Exit(1)
	}

	// 2. Float64Histogram configures explicit bucket boundaries for duration tracking
	boundedHist, err := meter.Float64Histogram(
		"db.query.duration",
		metric.WithDescription("Duration of database query execution"),
		metric.WithUnit("s"),
		metric.WithExplicitBucketBoundaries(0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 5.0),
	)
	if err != nil || boundedHist == nil {
		fmt.Fprintf(os.Stderr, "failed to create Float64Histogram with bucket boundaries: %v\n", err)
		os.Exit(1)
	}

	// 3. Float64Histogram records floating-point observations with contextual attributes
	boundedHist.Record(
		ctx,
		0.042,
		metric.WithAttributes(
			attribute.String("db.system", "postgresql"),
			attribute.String("db.operation", "SELECT"),
		),
	)
	boundedHist.Record(
		ctx,
		1.250,
		metric.WithAttributes(
			attribute.String("db.system", "postgresql"),
			attribute.String("db.operation", "UPDATE"),
		),
	)

	// 4. Float64Histogram executes without errors using standard MeterProvider
	recorder, err := sample.NewRequestLatencyRecorder(mp, "request-latency-meter")
	if err != nil || recorder == nil {
		fmt.Fprintf(os.Stderr, "failed to initialize RequestLatencyRecorder: %v\n", err)
		os.Exit(1)
	}
	if recorder.Histogram() == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Float64Histogram from recorder\n")
		os.Exit(1)
	}
	recorder.RecordDuration(ctx, 0.123, "/api/v1/items", 200)

	fmt.Println("All Float64Histogram contract assertions passed.")
}