wasilak/otelgo

package metrics

import (
    "context"
    "os"

    "dario.cat/mergo"
    "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"
    sdk "go.opentelemetry.io/otel/sdk/metric"
    "go.opentelemetry.io/otel/sdk/resource"
    semconv "go.opentelemetry.io/otel/semconv/v1.25.0"
)

type OtelGoMetricsConfig struct {
    Attributes []attribute.KeyValue `json:"attributes"` // Attributes specifies the attributes to be added to the metric resource. Default is an empty slice.
}

var defaultConfig = OtelGoMetricsConfig{
    Attributes: []attribute.KeyValue{
        semconv.ServiceNameKey.String(os.Getenv("OTEL_SERVICE_NAME")),
        semconv.ServiceVersionKey.String("v0.0.0"),
    },
}

func Init(ctx context.Context, config OtelGoMetricsConfig) (context.Context, *sdk.MeterProvider, error) {
    err := mergo.Merge(&defaultConfig, config, mergo.WithOverride)
    if err != nil {
        return ctx, nil, err
    }

    res, err := resource.New(ctx,
        resource.WithHost(),
        resource.WithContainer(),
        resource.WithProcess(),
        resource.WithTelemetrySDK(),
        resource.WithOS(),
        resource.WithFromEnv(),
        resource.WithAttributes(defaultConfig.Attributes...),
    )
    if err != nil {
        return ctx, nil, err
    }

    var exporter sdk.Exporter

    if os.Getenv("OTEL_EXPORTER_OTLP_PROTOCOL") == "grpc" {
        exporter, err = otlpmetricgrpc.New(ctx)
        if err != nil {
            return ctx, nil, err
        }
    } else {
        exporter, err = otlpmetrichttp.New(ctx)
        if err != nil {
            return ctx, nil, err
        }
    }

    meterProvider := sdk.NewMeterProvider(
        sdk.WithResource(res),
        sdk.WithReader(sdk.NewPeriodicReader(exporter)),
    )

    // defer func() {
    //     err := meterProvider.Shutdown(context.Background())
    //     if err != nil {
    //         log.Fatalln(err)
    //     }
    // }()

    otel.SetMeterProvider(meterProvider)

    return ctx, meterProvider, nil
}