Add draft of tracing package.

trace/tracing.go

@@ -0,0 +1,89 @@
+package libpack_trace
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	libpack_config "github.com/lukaszraczylo/graphql-monitoring-proxy/config"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/sdk/trace"
+	oteltrace "go.opentelemetry.io/otel/trace"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+func NewClient(otelGRPCCollector string, attr ...attribute.KeyValue) (func(), error) {
+	attr = append(attr, semconv.ServiceNameKey.String(libpack_config.PKG_NAME))
+	fmt.Printf("Starting OpenTelemetry tracer: otlp, configured with endpoint: %s\n", otelGRPCCollector)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	client := otlptracegrpc.NewClient(
+		otlptracegrpc.WithInsecure(),
+		otlptracegrpc.WithEndpoint(otelGRPCCollector),
+	)
+
+	exporter, err := otlptrace.New(ctx, client)
+	if err != nil {
+		fmt.Printf("ERROR: failed to create exporter: %v\n", err)
+		return nil, err
+	}
+
+	tp := trace.NewTracerProvider(
+		trace.WithSampler(trace.AlwaysSample()),
+		trace.WithBatcher(exporter, trace.WithMaxExportBatchSize(1), trace.WithBatchTimeout(30*time.Second)),
+		trace.WithResource(resource.NewWithAttributes(semconv.SchemaURL, attr...)),
+	)
+
+	otel.SetTracerProvider(tp)
+	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
+
+	shutdownFunc := func() {
+		shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer shutdownCancel()
+		fmt.Println("Shutting down otlp tracer")
+		if err := tp.Shutdown(shutdownCtx); err != nil {
+			fmt.Printf("ERROR: failed to shutdown tracer provider: %v\n", err)
+		}
+	}
+
+	return shutdownFunc, nil
+}
+
+func TraceContextInject(ctx context.Context) map[string]string {
+	carrier := propagation.MapCarrier{}
+	propagator := otel.GetTextMapPropagator()
+	propagator.Inject(ctx, carrier)
+	return map[string]string(carrier)
+}
+
+func TraceContextExtract(ctx context.Context, traceContext map[string]string) context.Context {
+	carrier := propagation.MapCarrier(traceContext)
+	propagator := otel.GetTextMapPropagator()
+	return propagator.Extract(ctx, carrier)
+}
+
+func StartSpanFromContext(ctx context.Context, operationName string) (context.Context, oteltrace.Span) {
+	tr := otel.GetTracerProvider().Tracer("")
+	return tr.Start(ctx, operationName, oteltrace.WithSpanKind(oteltrace.SpanKindInternal))
+}
+
+func ContinueSpanFromContext(ctx context.Context, operationName string) (context.Context, oteltrace.Span) {
+	tr := otel.GetTracerProvider().Tracer("")
+	options := []oteltrace.SpanStartOption{
+		oteltrace.WithSpanKind(oteltrace.SpanKindInternal),
+		oteltrace.WithAttributes(attribute.String("cont", "true")),
+	}
+	return tr.Start(ctx, operationName, options...)
+}
+
+func AddAttributesToSpan(span oteltrace.Span, attributes ...attribute.KeyValue) {
+	span.SetAttributes(attributes...)
+}