go.opentelemetry.io/otel/metric v1.38.0

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@v1.38.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0

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:sha256:15f02649b2e10cb0a77dc102852ae375d898544b2359670c20c8ad4b4b03b1e8","contract":["noop.NewMeterProvider returns a metric.MeterProvider whose Meter method creates a non-nil metric.Meter with WithInstrumentationVersion and WithSchemaURL options","Meter creates Int64Counter, Int64UpDownCounter, Float64Histogram, and Int64Gauge synchronous instruments and records measurements without error","Meter.Int64ObservableGauge and Meter.RegisterCallback register an asynchronous callback that can be cleanly unregistered via Registration.Unregister"],"goal":"verify pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0"],"schemaVersion":1,"symbols":["metric.MeterProvider","metric.Meter","metric.Int64Counter","metric.Int64UpDownCounter","metric.Float64Histogram","metric.Int64Gauge","metric.Int64ObservableGauge"]},"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@v1.38.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0","verifierAdapter":"golang@1"}

module example.com/sample

go 1.24.0

require go.opentelemetry.io/otel/metric v1.38.0

require go.opentelemetry.io/otel v1.38.0 // 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 v1.4.3 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 v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.38.0 h1:RkfdswUDRimDg0m2Az18RKOsnI8UDzppJAtj01/Ymk8=
go.opentelemetry.io/otel v1.38.0/go.mod h1:zcmtmQ1+YmQM9wrNsTGV/q/uyusom3P8RxwExxkZhjM=
go.opentelemetry.io/otel/metric v1.38.0 h1:Kl6lzIYGAh5M159u9NgiRkmoMKjvbsKtYRwgfrA6WpA=
go.opentelemetry.io/otel/metric v1.38.0/go.mod h1:kB5n/QoRM8YwmUahxvI3bO34eVtQf2i4utNVLr9gEmI=
go.opentelemetry.io/otel/trace v1.38.0 h1:Fxk5bKrDZJUH+AMyyIXGcFAPah0oRcT+LuNtJrmcNLE=
go.opentelemetry.io/otel/trace v1.38.0/go.mod h1:j1P9ivuFsTceSWe1oY+EeW3sc+Pp42sO++GHkg4wwhs=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

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

func main() {
	var provider metric.MeterProvider = noop.NewMeterProvider()
	meter := provider.Meter(
		"example.com/instruments",
		metric.WithInstrumentationVersion("1.0.0"),
		metric.WithSchemaURL("https://example.com/schema/1.0.0"),
	)
	if meter == nil {
		fmt.Fprintln(os.Stderr, "expected non-nil Meter")
		os.Exit(1)
	}

	counter, err := meter.Int64Counter(
		"requests.total",
		metric.WithDescription("Total requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil || counter == nil {
		fmt.Fprintf(os.Stderr, "Int64Counter failed: %v\n", err)
		os.Exit(1)
	}
	counter.Add(context.Background(), 5)

	upDown, err := meter.Int64UpDownCounter("connections.active")
	if err != nil || upDown == nil {
		fmt.Fprintf(os.Stderr, "Int64UpDownCounter failed: %v\n", err)
		os.Exit(1)
	}
	upDown.Add(context.Background(), 1)
	upDown.Add(context.Background(), -1)

	hist, err := meter.Float64Histogram(
		"request.duration",
		metric.WithExplicitBucketBoundaries(0.1, 0.5, 1.0),
	)
	if err != nil || hist == nil {
		fmt.Fprintf(os.Stderr, "Float64Histogram failed: %v\n", err)
		os.Exit(1)
	}
	hist.Record(context.Background(), 0.25)

	gauge, err := meter.Int64Gauge("queue.depth")
	if err != nil || gauge == nil {
		fmt.Fprintf(os.Stderr, "Int64Gauge failed: %v\n", err)
		os.Exit(1)
	}
	gauge.Record(context.Background(), 42)

	obsGauge, err := meter.Int64ObservableGauge(
		"memory.bytes",
		metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
			o.Observe(1024)
			return nil
		}),
	)
	if err != nil || obsGauge == nil {
		fmt.Fprintf(os.Stderr, "Int64ObservableGauge failed: %v\n", err)
		os.Exit(1)
	}

	reg, err := meter.RegisterCallback(
		func(_ context.Context, o metric.Observer) error {
			o.ObserveInt64(obsGauge, 2048)
			return nil
		},
		obsGauge,
	)
	if err != nil || reg == nil {
		fmt.Fprintf(os.Stderr, "RegisterCallback failed: %v\n", err)
		os.Exit(1)
	}
	if err := reg.Unregister(); err != nil {
		fmt.Fprintf(os.Stderr, "Unregister failed: %v\n", err)
		os.Exit(1)
	}
}