pkg/tracing/tracing.go

package tracing

import (
	"context"
	"fmt"
	"net/http"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
	"go.opentelemetry.io/otel/sdk/resource"
	"go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"

	"git.ifooth.com/common/pkg/config"
	"git.ifooth.com/common/pkg/version"
)

// TracingHandler
func TracingHandler(operation string) func(next http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		fn := func(w http.ResponseWriter, r *http.Request) {
			next.ServeHTTP(w, r)
		}
		return otelhttp.NewHandler(http.HandlerFunc(fn), operation)
	}
}

// newResource
func NewResource(serviceName, runEnv string) (*resource.Resource, error) {
	r, err := resource.Merge(
		resource.Default(),
		resource.NewWithAttributes(
			semconv.SchemaURL,
			semconv.ServiceName(serviceName),
			semconv.ServiceVersion(version.Version),
			attribute.String("run_env", runEnv),
		),
	)

	if err != nil {
		return nil, fmt.Errorf("creating trace resource: %w", err)
	}

	return r, nil
}

// newExporter
func NewExporter(ctx context.Context, conf *config.Tracing) (trace.SpanExporter, error) {
	client := otlptracegrpc.NewClient(
		otlptracegrpc.WithEndpoint(conf.Endpoint),
		otlptracegrpc.WithInsecure(),
	)

	exporter, err := otlptrace.New(ctx, client)
	if err != nil {
		return nil, fmt.Errorf("creating OTLP trace exporter: %w", err)
	}

	return exporter, nil
}