stdoutmetric should output some bucket information

[david-gang]

Problem Statement

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I configured the globalmetricsprovider with stdoutmetric and histogram with 101 buckets

exporter, err := stdoutmetric.New(stdoutmetric.WithPrettyPrint())
	if err != nil {
		log.Fatalln("failed to initialize metric stdout exporter:", err)
	}
	var boundaries []float64
	for i := 0.0; i <= 1000.0; i += 10 {
		boundaries = append(boundaries, i)
	}
	cont := controller.New(
		processor.NewFactory(
			simple.NewWithHistogramDistribution(histogram.WithExplicitBoundaries(boundaries)),
			exporter,
		),
		controller.WithExporter(exporter),
		controller.WithResource(newResource()),
	)
	if err := cont.Start(context.Background()); err != nil {
		log.Fatalln("failed to start the metric controller:", err)
	}
	global.SetMeterProvider(cont)

then i added afterwards a middleware of gin which measures latency:

func Logger() gin.HandlerFunc {
	provider := global.GetMeterProvider()
	meter := provider.Meter("gin-middleware")
	requestTimeStat, err := meter.NewInt64Histogram("request-latency")
	if err != nil {
		log.Fatalln("failed to create histogram", err)
	}

	ctx := context.Background()
	return func(c *gin.Context) {
		t := time.Now()
		c.Next()
		latency := time.Since(t).Milliseconds()
		requestTimeStat.Record(ctx, latency)
	}
}

The output was lacking all the bucket data and has just

	{
		"Name": "request-latency{environment=demo,service.name=coolResource,service.version=v0.1.0,telemetry.sdk.language=go,telemetry.sdk.name=opentelemetry,telemetry.sdk.version=1.1.0,instrumentation.name=gin-middleware}",
		"Sum": 2737
	}

I debugged the issue and found out https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/stdout/stdoutmetric/metric.go#L38

type line struct {
	Name      string      `json:"Name"`
	Min       interface{} `json:"Min,omitempty"`
	Max       interface{} `json:"Max,omitempty"`
	Sum       interface{} `json:"Sum,omitempty"`
	Count     interface{} `json:"Count,omitempty"`
	LastValue interface{} `json:"Last,omitempty"`

	// Note: this is a pointer because omitempty doesn't work when time.IsZero()
	Timestamp *time.Time `json:"Timestamp,omitempty"`
}

the output was missing all bucket info

Proposed Solution

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Could the bucket info be added so all non empty buckets would be printed or if we fear that it would be too much than maybe the first 10 with dots ?

Alternatives

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Maybe it should be warned somewhere in a log that bucket info is missing

Prior Art

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Additional Context

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[MrAlias]

Likely duplicate of #954

[MrAlias]

Duplicate of #954