go.opentelemetry.io/otel/metric v1.35.0: MeterProvider, Meter, Int64Counter

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 pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - runtime: node@22.23.2

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.

package sample

import (
	"context"
	"testing"

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

func TestContractMetrics(t *testing.T) {
	ctx := context.Background()

	// 1. MeterProvider initialization with noop provider
	mp := noop.NewMeterProvider()
	appMetrics, err := NewAppMetrics(mp, "demo-service")
	if err != nil {
		t.Fatalf("expected successful metric creation, got %v", err)
	}

	if appMetrics == nil {
		t.Fatal("expected non-nil AppMetrics")
	}

	// 2. Int64Counter records measurements
	appMetrics.RecordRequest(ctx, 1)
	appMetrics.RecordRequest(ctx, 5)

	// 3. Int64UpDownCounter records positive and negative increments
	appMetrics.UserLoggedIn(ctx)
	appMetrics.UserLoggedOut(ctx)

	// 4. Float64Histogram records duration measurements
	appMetrics.RecordLatency(ctx, 123.45)
	appMetrics.RecordLatency(ctx, 45.67)

	// 5. Verify direct Meter creation with options
	meter := mp.Meter(
		"custom-meter",
		metric.WithInstrumentationVersion("v1.35.0"),
		metric.WithSchemaURL("https://opentelemetry.io/schemas/1.24.0"),
	)
	if meter == nil {
		t.Fatal("expected non-nil Meter")
	}

	gauge, err := meter.Int64ObservableGauge(
		"system.memory.usage",
		metric.WithDescription("Observable memory usage in bytes"),
		metric.WithUnit("By"),
	)
	if err != nil {
		t.Fatalf("failed to create observable gauge: %v", err)
	}
	if gauge == nil {
		t.Fatal("expected non-nil observable gauge")
	}
}

{"case":{"caseId":"case:sha256:322ed406939453baa950961e2b008957dcf7139ab7becdcd74d50fa69614e4dc","contract":["MeterProvider creates Meter instances with instrumentation configuration","Meter creates Int64Counter, Int64UpDownCounter, and Float64Histogram instruments","Int64Counter records non-negative metric measurements","Int64UpDownCounter records bi-directional gauge adjustments","Float64Histogram records duration measurements with explicit units"],"goal":"verify pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0"],"schemaVersion":1,"symbols":["MeterProvider","Meter","Int64Counter","Int64UpDownCounter","Float64Histogram"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"alpine","ecosystem":"golang","language":"go","libc":"musl","moduleSystem":"go-modules","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","runtimeVersion":"1.26","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0","symbols":["MeterProvider","Meter","Int64Counter","Int64UpDownCounter","Float64Histogram"],"verifierAdapter":"golang@1"}

module sample

go 1.24

require go.opentelemetry.io/otel/metric v1.35.0

require go.opentelemetry.io/otel v1.35.0 // indirect

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 v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
github.com/go-logr/logr v1.4.2/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 v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.35.0 h1:xKWKPxrxB6OtMCbmMY021CqC45J+3Onta9MqjhnusiQ=
go.opentelemetry.io/otel v1.35.0/go.mod h1:UEqy8Zp11hpkUrL73gSlELM0DupHoiq72dR+Zqel/+Y=
go.opentelemetry.io/otel/metric v1.35.0 h1:0znxYu2SNyuMSQT4Y9WDWej0VpcsxkuklLa4/siN90M=
go.opentelemetry.io/otel/metric v1.35.0/go.mod h1:nKVFgxBZ2fReX6IlyW28MgZojkoAkJGaE8CpgeAU3oE=
go.opentelemetry.io/otel/trace v1.35.0 h1:dPpEfJu1sDIqruz7BHFG3c7528f6ddfSWfFDVt/xgMs=
go.opentelemetry.io/otel/trace v1.35.0/go.mod h1:WUk7DtFp1Aw2MkvqGdwiXYDZZNvA/1J8o6xRXLrIkyc=
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/metric"
	"go.opentelemetry.io/otel/metric/noop"
)

// AppMetrics holds instruments for application monitoring.
type AppMetrics struct {
	meter         metric.Meter
	requestCount  metric.Int64Counter
	activeUsers   metric.Int64UpDownCounter
	latencyMillis metric.Float64Histogram
}

// NewAppMetrics initializes metric instruments using the provided MeterProvider.
// If provider is nil, a no-op MeterProvider is used.
func NewAppMetrics(provider metric.MeterProvider, meterName string) (*AppMetrics, error) {
	if provider == nil {
		provider = noop.NewMeterProvider()
	}

	meter := provider.Meter(
		meterName,
		metric.WithInstrumentationVersion("v1.35.0"),
	)

	reqCounter, err := meter.Int64Counter(
		"http.server.request_count",
		metric.WithDescription("Total count of processed HTTP requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil {
		return nil, fmt.Errorf("create request_count counter: %w", err)
	}

	usersUpDown, err := meter.Int64UpDownCounter(
		"http.server.active_users",
		metric.WithDescription("Current number of active users"),
		metric.WithUnit("{user}"),
	)
	if err != nil {
		return nil, fmt.Errorf("create active_users upDownCounter: %w", err)
	}

	latencyHist, err := meter.Float64Histogram(
		"http.server.duration",
		metric.WithDescription("HTTP request duration in milliseconds"),
		metric.WithUnit("ms"),
	)
	if err != nil {
		return nil, fmt.Errorf("create duration histogram: %w", err)
	}

	return &AppMetrics{
		meter:         meter,
		requestCount:  reqCounter,
		activeUsers:   usersUpDown,
		latencyMillis: latencyHist,
	}, nil
}

// RecordRequest increments the request count.
func (m *AppMetrics) RecordRequest(ctx context.Context, count int64) {
	m.requestCount.Add(ctx, count)
}

// UserLoggedIn tracks a newly active user.
func (m *AppMetrics) UserLoggedIn(ctx context.Context) {
	m.activeUsers.Add(ctx, 1)
}

// UserLoggedOut tracks a disconnected user.
func (m *AppMetrics) UserLoggedOut(ctx context.Context) {
	m.activeUsers.Add(ctx, -1)
}

// RecordLatency records a latency observation.
func (m *AppMetrics) RecordLatency(ctx context.Context, durationMs float64) {
	m.latencyMillis.Record(ctx, durationMs)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/metric@v1.35.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "runtime": "node@22.23.2"
  }
}