Add tracing to tlsconmon

otel/otel.go

@@ -0,0 +1,75 @@
+package otel
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.32.0"
+)
+
+func SetupOTEL(ctx context.Context, traceEndpoint string) (shutdown func(context.Context) error, err error) {
+	var shutdownFuncs []func(context.Context) error
+
+	shutdown = func(ctx context.Context) error {
+		var err error
+		for _, fn := range shutdownFuncs {
+			err = errors.Join(err, fn(ctx))
+		}
+		shutdownFuncs = nil
+		return err
+	}
+
+	handlerErr := func(inErr error) {
+		err = errors.Join(inErr, shutdown(ctx))
+	}
+
+	prop := newPropagator()
+	otel.SetTextMapPropagator(prop)
+
+	tracerProvider, err := newTracerProvider(ctx, traceEndpoint)
+	if err != nil {
+		handlerErr(err)
+		return
+	}
+	shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
+	otel.SetTracerProvider(tracerProvider)
+
+	return
+}
+
+func newPropagator() propagation.TextMapPropagator {
+	return propagation.NewCompositeTextMapPropagator(
+		propagation.TraceContext{},
+		propagation.Baggage{},
+	)
+}
+
+func newTracerProvider(ctx context.Context, traceEndpoint string) (*trace.TracerProvider, error) {
+	traceExporter, err := otlptracehttp.New(ctx,
+		otlptracehttp.WithEndpoint(traceEndpoint),
+		otlptracehttp.WithInsecure(),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	traceResource, err := resource.New(ctx, resource.WithAttributes(
+		semconv.ServiceNamespaceKey.String("t-juice.club"),
+		semconv.ServiceName("labmon"),
+	))
+	if err != nil {
+		return nil, err
+	}
+	tracerProvider := trace.NewTracerProvider(
+		trace.WithBatcher(traceExporter, trace.WithBatchTimeout(time.Second)),
+		trace.WithResource(traceResource),
+	)
+
+	return tracerProvider, nil
+}