go.opentelemetry.io/otel/metric v1.38.0: 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 metric.Meter in 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
Demonstrate these symbols/APIs:
  - 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:sha256:5851765799e8e29ee7df48c5edb631070b9a20ecd1c7410b00063da147f3f144","contract":["noop.NewMeterProvider().Meter returns a non-nil metric.Meter configured with WithInstrumentationVersion and WithSchemaURL","metric.Meter creates synchronous instruments Int64Counter, Float64Counter, Int64UpDownCounter, Float64Histogram, and Int64Gauge without error and records measurements","metric.Meter.Int64ObservableGauge and metric.Meter.RegisterCallback register an asynchronous observation callback that unregisters cleanly via Registration.Unregister"],"goal":"verify metric.Meter in 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.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@v1.38.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0","symbols":["metric.Meter"],"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 metric.Meter in pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/metric@v1.38.0"
  ],
  "symbols": [
    "metric.Meter"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

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

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

	ctx := context.Background()

	intCounter, err := meter.Int64Counter(
		"requests.count",
		metric.WithDescription("Total requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil || intCounter == nil {
		fmt.Fprintf(os.Stderr, "Meter.Int64Counter failed: %v\n", err)
		os.Exit(1)
	}
	intCounter.Add(ctx, 1)

	floatCounter, err := meter.Float64Counter("bytes.sent")
	if err != nil || floatCounter == nil {
		fmt.Fprintf(os.Stderr, "Meter.Float64Counter failed: %v\n", err)
		os.Exit(1)
	}
	floatCounter.Add(ctx, 128.5)

	upDown, err := meter.Int64UpDownCounter("connections.open")
	if err != nil || upDown == nil {
		fmt.Fprintf(os.Stderr, "Meter.Int64UpDownCounter failed: %v\n", err)
		os.Exit(1)
	}
	upDown.Add(ctx, 2)
	upDown.Add(ctx, -1)

	hist, err := meter.Float64Histogram(
		"request.latency",
		metric.WithExplicitBucketBoundaries(0.05, 0.1, 0.5, 1.0),
	)
	if err != nil || hist == nil {
		fmt.Fprintf(os.Stderr, "Meter.Float64Histogram failed: %v\n", err)
		os.Exit(1)
	}
	hist.Record(ctx, 0.12)

	gauge, err := meter.Int64Gauge("workers.busy")
	if err != nil || gauge == nil {
		fmt.Fprintf(os.Stderr, "Meter.Int64Gauge failed: %v\n", err)
		os.Exit(1)
	}
	gauge.Record(ctx, 4)

	obsGauge, err := meter.Int64ObservableGauge(
		"heap.bytes",
		metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
			o.Observe(4096)
			return nil
		}),
	)
	if err != nil || obsGauge == nil {
		fmt.Fprintf(os.Stderr, "Meter.Int64ObservableGauge failed: %v\n", err)
		os.Exit(1)
	}

	reg, err := meter.RegisterCallback(
		func(_ context.Context, o metric.Observer) error {
			o.ObserveInt64(obsGauge, 8192)
			return nil
		},
		obsGauge,
	)
	if err != nil || reg == nil {
		fmt.Fprintf(os.Stderr, "Meter.RegisterCallback failed: %v\n", err)
		os.Exit(1)
	}
	if err := reg.Unregister(); err != nil {
		fmt.Fprintf(os.Stderr, "Registration.Unregister failed: %v\n", err)
		os.Exit(1)
	}
}