add opentelemetry tracing

cmd/kuriweb/trace.go

@@ -0,0 +1,132 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"time"
+
+	"git.loyso.art/frx/kurious/internal/common/config"
+	"git.loyso.art/frx/kurious/pkg/xdefault"
+
+	"github.com/gorilla/mux"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+var webtracer = otel.Tracer("kuriweb")
+
+type shutdownFunc func(context.Context) error
+
+func setupOtelSDK(ctx context.Context, cfg config.Trace) (shutdown shutdownFunc, err error) {
+	var shutdownFuncs []shutdownFunc
+
+	shutdown = func(ctx context.Context) error {
+		var err error
+		for _, f := range shutdownFuncs {
+			err = errors.Join(err, f(ctx))
+		}
+		shutdownFuncs = nil
+		return err
+	}
+
+	handleError := func(inErr error) error {
+		err = errors.Join(inErr, shutdown(ctx))
+		return err
+	}
+
+	prop := newPropagator()
+	otel.SetTextMapPropagator(prop)
+
+	tracerProvider, err := newTraceProvider(ctx, cfg.Endpoint, cfg.LicenseKey)
+	if err != nil {
+		return nil, handleError(err)
+	}
+	shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
+	otel.SetTracerProvider(tracerProvider)
+
+	meterProvider, err := newMeterProvider()
+	if err != nil {
+		return nil, handleError(err)
+	}
+	shutdownFuncs = append(shutdownFuncs, meterProvider.Shutdown)
+	otel.SetMeterProvider(meterProvider)
+
+	return shutdown, nil
+}
+
+func newPropagator() propagation.TextMapPropagator {
+	return propagation.NewCompositeTextMapPropagator(
+		propagation.TraceContext{},
+		propagation.Baggage{},
+	)
+}
+
+const defaultNewRelicEndpoint = "otlp.eu01.nr-data.net:443"
+
+func newTraceProvider(ctx context.Context, endpoint, licensekey string) (traceProvider *trace.TracerProvider, err error) {
+	opts := make([]trace.TracerProviderOption, 0, 2)
+	opts = append(
+		opts,
+		trace.WithSampler(trace.AlwaysSample()),
+		trace.WithResource(resource.Default()),
+	)
+
+	if licensekey != "" {
+		endpoint = xdefault.WithFallback(endpoint, defaultNewRelicEndpoint)
+		client, err := otlptracegrpc.New(
+			ctx,
+			otlptracegrpc.WithEndpoint(endpoint),
+			otlptracegrpc.WithHeaders(map[string]string{
+				"api-key": licensekey,
+			}),
+		)
+		if err != nil {
+			return nil, fmt.Errorf("making grpc client: %w", err)
+		}
+
+		opts = append(opts, trace.WithBatcher(client, trace.WithBatchTimeout(time.Second*10)))
+	} else {
+		traceExporter, err := stdouttrace.New(
+			stdouttrace.WithPrettyPrint())
+		if err != nil {
+			return nil, err
+		}
+
+		opts = append(
+			opts,
+			trace.WithBatcher(traceExporter, trace.WithBatchTimeout(time.Second*5)),
+		)
+	}
+
+	traceProvider = trace.NewTracerProvider(opts...)
+
+	return traceProvider, nil
+}
+
+func newMeterProvider() (*metric.MeterProvider, error) {
+	metricExporter, err := stdoutmetric.New()
+	if err != nil {
+		return nil, err
+	}
+
+	meterProvider := metric.NewMeterProvider(
+		metric.WithReader(metric.NewPeriodicReader(metricExporter,
+			// Default is 1m. Set to 3s for demonstrative purposes.
+			metric.WithInterval(60*time.Second))),
+	)
+	return meterProvider, nil
+}
+
+func muxHandleFunc(router *mux.Router, path string, hf http.HandlerFunc) *mux.Route {
+	h := otelhttp.WithRouteTag(path, hf)
+	return router.Handle(path, h)
+}