go.opentelemetry.io/otel/metric v1.24.0: Meter

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.Meter in pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/metric.Meter

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:cc9fa9b64562e68b090ff92b7d07e6ef075e3f34734a23e8fd3872d7a63b3242","contract":["Meter creates synchronous Int64Counter instruments and records measurements with attributes","Meter creates synchronous Int64UpDownCounter instruments and adjusts values","Meter creates synchronous Float64Histogram instruments with explicit bucket boundaries","Meter creates asynchronous Int64ObservableGauge instruments with description and unit","Meter registers and unregisters asynchronous callbacks observing instruments with RegisterCallback"],"goal":"verify go.opentelemetry.io/otel/metric.Meter in pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/metric.Meter"]},"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@v1.24.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0","symbols":["go.opentelemetry.io/otel/metric.Meter"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22

require go.opentelemetry.io/otel/metric v1.24.0

require go.opentelemetry.io/otel v1.24.0

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 v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
github.com/go-logr/logr v1.4.1/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 v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
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 v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
go.opentelemetry.io/otel v1.24.0 h1:0LAOdjNmQeSTzGBzduGe/rU4tZhMwL5rWgtp9Ku5Jfo=
go.opentelemetry.io/otel v1.24.0/go.mod h1:W7b9Ozg4nkF5tWI5zsXkaKKDjdVjpD4oAt9Qi/MArHo=
go.opentelemetry.io/otel/metric v1.24.0 h1:6EhoGWWK28x1fbpA4tYTOWBkPefTDQnb8WSGXlc88kI=
go.opentelemetry.io/otel/metric v1.24.0/go.mod h1:VYhLe1rFfxuTXLgj4CBiyz+9WYBA8pNGJgDcSFRKBco=
go.opentelemetry.io/otel/trace v1.24.0 h1:CsKnnL4dUAr/0llH9FKuc698G04IrpWV0MQA/Y1YELI=
go.opentelemetry.io/otel/trace v1.24.0/go.mod h1:HPc3Xr/cOApsBI154IU0OI0HJexz+aw5uPdbs3UCjNU=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"context"
	"fmt"

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

func main() {
	provider := noop.NewMeterProvider()
	meter := provider.Meter("example.com/meter-sample")

	ctx := context.Background()

	counter, err := meter.Int64Counter(
		"http.requests",
		metric.WithDescription("Total number of HTTP requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil {
		panic(err)
	}
	counter.Add(ctx, 1, metric.WithAttributes(attribute.String("path", "/api/v1/status")))

	fmt.Println("Metric Meter sample initialized and recorded measurement successfully.")
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/metric.Meter in pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/metric@v1.24.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/metric.Meter"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

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

func main() {
	ctx := context.Background()
	provider := noop.NewMeterProvider()
	meter := provider.Meter("sample-test-meter")
	if meter == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Meter\n")
		os.Exit(1)
	}

	// 1. Meter creates synchronous Int64Counter instruments and records measurements with attributes
	counter, err := meter.Int64Counter(
		"app.requests.total",
		metric.WithDescription("Total HTTP requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create Int64Counter: %v\n", err)
		os.Exit(1)
	}
	if counter == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Int64Counter\n")
		os.Exit(1)
	}
	counter.Add(ctx, 10, metric.WithAttributes(attribute.String("route", "/users")))

	// 2. Meter creates synchronous Int64UpDownCounter instruments and adjusts values
	upDownCounter, err := meter.Int64UpDownCounter(
		"app.connections.active",
		metric.WithDescription("Active connections"),
		metric.WithUnit("{connection}"),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create Int64UpDownCounter: %v\n", err)
		os.Exit(1)
	}
	if upDownCounter == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Int64UpDownCounter\n")
		os.Exit(1)
	}
	upDownCounter.Add(ctx, 5)
	upDownCounter.Add(ctx, -2)

	// 3. Meter creates synchronous Float64Histogram instruments with explicit bucket boundaries
	histogram, err := meter.Float64Histogram(
		"app.request.duration",
		metric.WithDescription("Request latency in seconds"),
		metric.WithUnit("s"),
		metric.WithExplicitBucketBoundaries(0.01, 0.05, 0.1, 0.5, 1.0),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create Float64Histogram: %v\n", err)
		os.Exit(1)
	}
	if histogram == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Float64Histogram\n")
		os.Exit(1)
	}
	histogram.Record(ctx, 0.042, metric.WithAttributes(attribute.Int("status_code", 200)))

	// 4. Meter creates asynchronous Int64ObservableGauge instruments with description and unit
	gauge, err := meter.Int64ObservableGauge(
		"app.memory.usage",
		metric.WithDescription("Memory usage in bytes"),
		metric.WithUnit("By"),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create Int64ObservableGauge: %v\n", err)
		os.Exit(1)
	}
	if gauge == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Int64ObservableGauge\n")
		os.Exit(1)
	}

	// 5. Meter registers and unregisters asynchronous callbacks observing instruments with RegisterCallback
	reg, err := meter.RegisterCallback(
		func(cbCtx context.Context, obs metric.Observer) error {
			obs.ObserveInt64(gauge, 1024*1024*64, metric.WithAttributes(attribute.String("pool", "heap")))
			return nil
		},
		gauge,
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to register callback: %v\n", err)
		os.Exit(1)
	}
	if reg == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Registration\n")
		os.Exit(1)
	}

	if err := reg.Unregister(); err != nil {
		fmt.Fprintf(os.Stderr, "failed to unregister callback: %v\n", err)
		os.Exit(1)
	}

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