go.opentelemetry.io/otel/sdk/metric v1.44.0: InstrumentKindObservableGauge

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/sdk/metric.InstrumentKindObservableGauge in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge

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:f2767492436858780c0ec9e51753fa2be63fa4d8f2f41fff90855dfde2a19535","contract":["InstrumentKindObservableGauge has kind value 6 and string representation ObservableGauge","DefaultAggregationSelector selects AggregationLastValue for InstrumentKindObservableGauge","DeltaTemporalitySelector returns CumulativeTemporality for InstrumentKindObservableGauge","NewView matches and customizes observable gauges using InstrumentKindObservableGauge criteria","NewView with InstrumentKindObservableGauge leaves other instrument kinds unchanged","ManualReader collects gauge observations through MeterProvider configured with InstrumentKindObservableGauge view"],"goal":"verify go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge"]},"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/sdk/metric@v1.44.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0","symbols":["go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require (
	go.opentelemetry.io/otel/metric v1.44.0
	go.opentelemetry.io/otel/sdk/metric v1.44.0
)

require (
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	github.com/go-logr/logr v1.4.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	github.com/google/uuid v1.6.0 // indirect
	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
	go.opentelemetry.io/otel v1.44.0 // indirect
	go.opentelemetry.io/otel/sdk v1.44.0 // indirect
	go.opentelemetry.io/otel/trace v1.44.0 // indirect
	golang.org/x/sys v0.45.0 // 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 v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
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/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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 v1.44.0 h1:JjwHmHpA4iZ3wBxluu2fbbE7j4kqlE8jXyAyPXH7HqU=
go.opentelemetry.io/otel v1.44.0/go.mod h1:BMgjTHL9WPRlRjL2oZCBTL4whCGtXch2H4BhOPIAyYc=
go.opentelemetry.io/otel/metric v1.44.0 h1:1w0gILTcHdr3YI+ixLyjemwrVnsMURbTZFrSYCdDdmc=
go.opentelemetry.io/otel/metric v1.44.0/go.mod h1:8O7hanEPBNgEMmybD3s2VBKcgWOCsA6tzHBPODAiquo=
go.opentelemetry.io/otel/metric/x v0.66.0 h1:YkCrx1zLOChi9ZcZ6euupOcsgzbVlec7D/xoEU1+cTA=
go.opentelemetry.io/otel/metric/x v0.66.0/go.mod h1:d1+BDj9t96do0/1LoU1ayfCv79ZgNE41qbhBvnMOBZk=
go.opentelemetry.io/otel/sdk v1.44.0 h1:nHYwb9lK+fJPU/dnT6s7W7Z8itMWyqrnVfbheVYrZ58=
go.opentelemetry.io/otel/sdk v1.44.0/go.mod h1:Osuydd3Se74nqjAKxid74N5eC+jfEqfTegHRnq58oK0=
go.opentelemetry.io/otel/sdk/metric v1.44.0 h1:3LlKgI+VjbVsjNRFZJZAJ30WjXC5VkNRks6si09iEfI=
go.opentelemetry.io/otel/sdk/metric v1.44.0/go.mod h1:5B5pMARnXxKhltooO4xUuCBorl65a4EpnTalObqOigA=
go.opentelemetry.io/otel/trace v1.44.0 h1:jxF5CsGYCe74MCRx2X4g7WsY/VBKRqqpNvXlX/6gtIk=
go.opentelemetry.io/otel/trace v1.44.0/go.mod h1:oLl1jrMQAVo6v3GAggN+1VH9VIz9iUSvW53sW1Q8PIE=
golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
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"
	"os"

	otelmetric "go.opentelemetry.io/otel/metric"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

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

	// Demonstrate InstrumentKindObservableGauge usage with View and MeterProvider.
	// We create a view that matches any instrument of kind InstrumentKindObservableGauge
	// and customizes its description and unit.
	gaugeView := sdkmetric.NewView(
		sdkmetric.Instrument{
			Kind: sdkmetric.InstrumentKindObservableGauge,
		},
		sdkmetric.Stream{
			Description: "Transformed gauge metric via InstrumentKindObservableGauge view",
			Unit:        "percent",
		},
	)

	reader := sdkmetric.NewManualReader()
	meterProvider := sdkmetric.NewMeterProvider(
		sdkmetric.WithReader(reader),
		sdkmetric.WithView(gaugeView),
	)
	defer func() {
		if err := meterProvider.Shutdown(ctx); err != nil {
			fmt.Fprintf(os.Stderr, "failed to shutdown meter provider: %v\n", err)
		}
	}()

	meter := meterProvider.Meter("example.com/system-monitor")

	// Register an asynchronous gauge (ObservableGauge) instrument.
	gaugeValue := 75.5
	_, err := meter.Float64ObservableGauge(
		"system.memory.usage",
		otelmetric.WithDescription("Original raw memory usage"),
		otelmetric.WithUnit("By"),
		otelmetric.WithFloat64Callback(func(_ context.Context, obs otelmetric.Float64Observer) error {
			obs.Observe(gaugeValue)
			return nil
		}),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to register observable gauge: %v\n", err)
		os.Exit(1)
	}

	var rm metricdata.ResourceMetrics
	if err := reader.Collect(ctx, &rm); err != nil {
		fmt.Fprintf(os.Stderr, "failed to collect metrics: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Instrument kind: %s (%d)\n", sdkmetric.InstrumentKindObservableGauge.String(), sdkmetric.InstrumentKindObservableGauge)
	for _, sm := range rm.ScopeMetrics {
		for _, m := range sm.Metrics {
			fmt.Printf("Metric: %s, Description: %s, Unit: %s\n", m.Name, m.Description, m.Unit)
		}
	}
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.44.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/sdk/metric.InstrumentKindObservableGauge"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

	otelmetric "go.opentelemetry.io/otel/metric"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

func main() {
	if err := runContract(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract verification failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All InstrumentKindObservableGauge contract assertions passed successfully.")
}

func runContract() error {
	ctx := context.Background()

	// 1. Verify constant value and String representation
	if sdkmetric.InstrumentKindObservableGauge != 6 {
		return fmt.Errorf("expected InstrumentKindObservableGauge to have value 6, got %d", sdkmetric.InstrumentKindObservableGauge)
	}
	if got := sdkmetric.InstrumentKindObservableGauge.String(); got != "ObservableGauge" {
		return fmt.Errorf("expected string 'ObservableGauge', got %q", got)
	}

	// 2. Verify DefaultAggregationSelector mapping
	agg := sdkmetric.DefaultAggregationSelector(sdkmetric.InstrumentKindObservableGauge)
	if _, ok := agg.(sdkmetric.AggregationLastValue); !ok {
		return fmt.Errorf("expected DefaultAggregationSelector to return AggregationLastValue, got %T", agg)
	}

	// 3. Verify DeltaTemporalitySelector preserves CumulativeTemporality for gauge
	temporality := sdkmetric.DeltaTemporalitySelector(sdkmetric.InstrumentKindObservableGauge)
	if temporality != metricdata.CumulativeTemporality {
		return fmt.Errorf("expected DeltaTemporalitySelector for InstrumentKindObservableGauge to be CumulativeTemporality, got %v", temporality)
	}

	// 4 & 5. Verify NewView targeting InstrumentKindObservableGauge
	const customizedGaugeDesc = "Customized Observable Gauge Description"
	const customizedGaugeUnit = "ratio"
	view := sdkmetric.NewView(
		sdkmetric.Instrument{
			Kind: sdkmetric.InstrumentKindObservableGauge,
		},
		sdkmetric.Stream{
			Description: customizedGaugeDesc,
			Unit:        customizedGaugeUnit,
		},
	)

	reader := sdkmetric.NewManualReader()
	mp := sdkmetric.NewMeterProvider(
		sdkmetric.WithReader(reader),
		sdkmetric.WithView(view),
	)
	defer func() {
		_ = mp.Shutdown(ctx)
	}()

	meter := mp.Meter("test/observable-gauge-meter")

	// Register observable gauge (should match view)
	expectedValue := 88.5
	_, err := meter.Float64ObservableGauge(
		"test.cpu.load",
		otelmetric.WithDescription("Original cpu load description"),
		otelmetric.WithUnit("1"),
		otelmetric.WithFloat64Callback(func(_ context.Context, obs otelmetric.Float64Observer) error {
			obs.Observe(expectedValue)
			return nil
		}),
	)
	if err != nil {
		return fmt.Errorf("failed to register Float64ObservableGauge: %w", err)
	}

	// Register counter (should NOT match view)
	const counterDesc = "Counter should remain untouched"
	const counterUnit = "requests"
	counter, err := meter.Int64Counter(
		"test.requests.count",
		otelmetric.WithDescription(counterDesc),
		otelmetric.WithUnit(counterUnit),
	)
	if err != nil {
		return fmt.Errorf("failed to register Int64Counter: %w", err)
	}
	counter.Add(ctx, 5)

	// Collect metrics
	var rm metricdata.ResourceMetrics
	if err := reader.Collect(ctx, &rm); err != nil {
		return fmt.Errorf("failed to collect metrics from reader: %w", err)
	}

	var foundGauge, foundCounter bool
	for _, sm := range rm.ScopeMetrics {
		for _, m := range sm.Metrics {
			switch m.Name {
			case "test.cpu.load":
				foundGauge = true
				if m.Description != customizedGaugeDesc {
					return fmt.Errorf("expected gauge description %q, got %q", customizedGaugeDesc, m.Description)
				}
				if m.Unit != customizedGaugeUnit {
					return fmt.Errorf("expected gauge unit %q, got %q", customizedGaugeUnit, m.Unit)
				}
				gaugeData, ok := m.Data.(metricdata.Gauge[float64])
				if !ok {
					return fmt.Errorf("expected gauge data to be metricdata.Gauge[float64], got %T", m.Data)
				}
				if len(gaugeData.DataPoints) != 1 {
					return fmt.Errorf("expected 1 data point, got %d", len(gaugeData.DataPoints))
				}
				if gaugeData.DataPoints[0].Value != expectedValue {
					return fmt.Errorf("expected gauge value %f, got %f", expectedValue, gaugeData.DataPoints[0].Value)
				}
			case "test.requests.count":
				foundCounter = true
				if m.Description != counterDesc {
					return fmt.Errorf("expected counter description %q to remain untouched, got %q", counterDesc, m.Description)
				}
				if m.Unit != counterUnit {
					return fmt.Errorf("expected counter unit %q to remain untouched, got %q", counterUnit, m.Unit)
				}
			}
		}
	}

	if !foundGauge {
		return fmt.Errorf("observable gauge metric was not collected")
	}
	if !foundCounter {
		return fmt.Errorf("counter metric was not collected")
	}

	return nil
}