opcotech/elemo

package tracing

import (
    "context"
    "errors"
    "fmt"

    "go.opentelemetry.io/otel"
    otlptrace "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
    "go.opentelemetry.io/otel/propagation"
    "go.opentelemetry.io/otel/sdk/resource"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
    semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
    "go.opentelemetry.io/otel/trace"
    "go.opentelemetry.io/otel/trace/embedded"
    nooptrace "go.opentelemetry.io/otel/trace/noop"

    "github.com/opcotech/elemo/internal/config"
    "github.com/opcotech/elemo/internal/model"
)

var (
    ErrNoTracer        = errors.New("no tracer") // the tracer is missing
    noopTracerProvider = nooptrace.NewTracerProvider()
    noopTracer         = noopTracerProvider.Tracer("github.com/opcotech/elemo")
)

// Tracer re-defines the tracing.Tracer interface as the
type Tracer interface {
    embedded.Tracer
    Start(ctx context.Context, spanName string, opts ...trace.SpanStartOption) (context.Context, trace.Span)
}

// NewTracerProvider creates a new tracer provider.
func NewTracerProvider(ctx context.Context, version *model.VersionInfo, service string, cfg *config.TracingConfig) (trace.TracerProvider, error) {
    exporter, err := otlptrace.New(
        ctx,
        otlptrace.WithEndpoint(cfg.CollectorEndpoint),
        otlptrace.WithInsecure(),
    )
    if err != nil {
        return nil, err
    }

    tracerProvider := sdktrace.NewTracerProvider(
        sdktrace.WithResource(resource.NewWithAttributes(
            semconv.SchemaURL,
            semconv.ServiceNameKey.String(fmt.Sprintf("%s-%s", cfg.ServiceName, service)),
            semconv.ServiceVersionKey.String(version.Version),
        )),
        sdktrace.WithSampler(sdktrace.ParentBased(sdktrace.TraceIDRatioBased(cfg.TraceRatio))),
        sdktrace.WithBatcher(exporter),
    )
    otel.SetTracerProvider(tracerProvider)
    otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))

    return tracerProvider, err
}

// NoopTracer returns a noop tracer.
func NoopTracer() Tracer {
    return noopTracer
}