Add support to configure views with config.NewSdk (open-telemetry#5654)

CHANGELOG.md

@@ -11,6 +11,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Added
 
 - The `go.opentelemetry.io/contrib/config` add support to configure periodic reader interval and timeout. (#5661)
+- Add support to configure views when creating MeterProvider using the config package. (#5654)
 
 ### Fixed
 

config/metric.go

@@ -18,16 +18,22 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
 	otelprom "go.opentelemetry.io/otel/exporters/prometheus"
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/noop"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
 	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/resource"
 )
 
+var zeroScope instrumentation.Scope
+
+const instrumentKindUndefined = sdkmetric.InstrumentKind(0)
+
 func meterProvider(cfg configOptions, res *resource.Resource) (metric.MeterProvider, shutdownFunc, error) {
 	if cfg.opentelemetryConfig.MeterProvider == nil {
 		return noop.NewMeterProvider(), noopShutdown, nil
@@ -45,6 +51,15 @@ func meterProvider(cfg configOptions, res *resource.Resource) (metric.MeterProvi
 			errs = append(errs, err)
 		}
 	}
+	for _, vw := range cfg.opentelemetryConfig.MeterProvider.Views {
+		v, err := view(vw)
+		if err == nil {
+			opts = append(opts, sdkmetric.WithView(v))
+		} else {
+			errs = append(errs, err)
+		}
+	}
+
 	if len(errs) > 0 {
 		return noop.NewMeterProvider(), noopShutdown, errors.Join(errs...)
 	}
@@ -156,7 +171,7 @@ func otlpHTTPMetricExporter(ctx context.Context, otlpConfig *OTLPMetric) (sdkmet
 }
 
 func otlpGRPCMetricExporter(ctx context.Context, otlpConfig *OTLPMetric) (sdkmetric.Exporter, error) {
-	opts := []otlpmetricgrpc.Option{}
+	var opts []otlpmetricgrpc.Option
 
 	if len(otlpConfig.Endpoint) > 0 {
 		u, err := url.ParseRequestURI(otlpConfig.Endpoint)
@@ -266,3 +281,148 @@ func (rws readerWithServer) Shutdown(ctx context.Context) error {
 		rws.server.Shutdown(ctx),
 	)
 }
+
+func view(v View) (sdkmetric.View, error) {
+	if v.Selector == nil {
+		return nil, errors.New("view: no selector provided")
+	}
+
+	inst, err := instrument(*v.Selector)
+	if err != nil {
+		return nil, err
+	}
+
+	return sdkmetric.NewView(inst, stream(v.Stream)), nil
+}
+
+func instrument(vs ViewSelector) (sdkmetric.Instrument, error) {
+	kind, err := instrumentKind(vs.InstrumentType)
+	if err != nil {
+		return sdkmetric.Instrument{}, fmt.Errorf("view_selector: %w", err)
+	}
+	inst := sdkmetric.Instrument{
+		Name: strOrEmpty(vs.InstrumentName),
+		Unit: strOrEmpty(vs.Unit),
+		Kind: kind,
+		Scope: instrumentation.Scope{
+			Name:      strOrEmpty(vs.MeterName),
+			Version:   strOrEmpty(vs.MeterVersion),
+			SchemaURL: strOrEmpty(vs.MeterSchemaUrl),
+		},
+	}
+
+	if instrumentIsEmpty(inst) {
+		return sdkmetric.Instrument{}, errors.New("view_selector: empty selector not supporter")
+	}
+	return inst, nil
+}
+
+func stream(vs *ViewStream) sdkmetric.Stream {
+	if vs == nil {
+		return sdkmetric.Stream{}
+	}
+
+	return sdkmetric.Stream{
+		Name:            strOrEmpty(vs.Name),
+		Description:     strOrEmpty(vs.Description),
+		Aggregation:     aggregation(vs.Aggregation),
+		AttributeFilter: attributeFilter(vs.AttributeKeys),
+	}
+}
+
+func attributeFilter(attributeKeys []string) attribute.Filter {
+	var attrKeys []attribute.Key
+	for _, attrStr := range attributeKeys {
+		attrKeys = append(attrKeys, attribute.Key(attrStr))
+	}
+	return attribute.NewAllowKeysFilter(attrKeys...)
+}
+
+func aggregation(aggr *ViewStreamAggregation) sdkmetric.Aggregation {
+	if aggr == nil {
+		return nil
+	}
+
+	if aggr.Base2ExponentialBucketHistogram != nil {
+		return sdkmetric.AggregationBase2ExponentialHistogram{
+			MaxSize:  int32(intOrZero(aggr.Base2ExponentialBucketHistogram.MaxSize)),
+			MaxScale: int32(intOrZero(aggr.Base2ExponentialBucketHistogram.MaxScale)),
+			// Need to negate because config has the positive action RecordMinMax.
+			NoMinMax: !boolOrFalse(aggr.Base2ExponentialBucketHistogram.RecordMinMax),
+		}
+	}
+	if aggr.Default != nil {
+		// TODO: Understand what to set here.
+		return nil
+	}
+	if aggr.Drop != nil {
+		return sdkmetric.AggregationDrop{}
+	}
+	if aggr.ExplicitBucketHistogram != nil {
+		return sdkmetric.AggregationExplicitBucketHistogram{
+			Boundaries: aggr.ExplicitBucketHistogram.Boundaries,
+			// Need to negate because config has the positive action RecordMinMax.
+			NoMinMax: !boolOrFalse(aggr.ExplicitBucketHistogram.RecordMinMax),
+		}
+	}
+	if aggr.LastValue != nil {
+		return sdkmetric.AggregationLastValue{}
+	}
+	if aggr.Sum != nil {
+		return sdkmetric.AggregationSum{}
+	}
+	return nil
+}
+
+func instrumentKind(vsit *ViewSelectorInstrumentType) (sdkmetric.InstrumentKind, error) {
+	if vsit == nil {
+		// Equivalent to instrumentKindUndefined.
+		return instrumentKindUndefined, nil
+	}
+
+	switch *vsit {
+	case ViewSelectorInstrumentTypeCounter:
+		return sdkmetric.InstrumentKindCounter, nil
+	case ViewSelectorInstrumentTypeUpDownCounter:
+		return sdkmetric.InstrumentKindUpDownCounter, nil
+	case ViewSelectorInstrumentTypeHistogram:
+		return sdkmetric.InstrumentKindHistogram, nil
+	case ViewSelectorInstrumentTypeObservableCounter:
+		return sdkmetric.InstrumentKindObservableCounter, nil
+	case ViewSelectorInstrumentTypeObservableUpDownCounter:
+		return sdkmetric.InstrumentKindObservableUpDownCounter, nil
+	case ViewSelectorInstrumentTypeObservableGauge:
+		return sdkmetric.InstrumentKindObservableGauge, nil
+	}
+
+	return instrumentKindUndefined, errors.New("instrument_type: invalid value")
+}
+
+func instrumentIsEmpty(i sdkmetric.Instrument) bool {
+	return i.Name == "" &&
+		i.Description == "" &&
+		i.Kind == instrumentKindUndefined &&
+		i.Unit == "" &&
+		i.Scope == zeroScope
+}
+
+func boolOrFalse(pBool *bool) bool {
+	if pBool == nil {
+		return false
+	}
+	return *pBool
+}
+
+func intOrZero(pInt *int) int {
+	if pInt == nil {
+		return 0
+	}
+	return *pInt
+}
+
+func strOrEmpty(pStr *string) string {
+	if pStr == nil {
+		return ""
+	}
+	return *pStr
+}