150 lines
3.6 KiB
Go
150 lines
3.6 KiB
Go
package logz
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import (
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"context"
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"fmt"
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"log"
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"net/http"
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"runtime"
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"strconv"
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"time"
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"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
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"go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
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"go.opentelemetry.io/otel/propagation"
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"go.opentelemetry.io/otel/sdk/resource"
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sdktrace "go.opentelemetry.io/otel/sdk/trace"
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semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
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"go.opentelemetry.io/otel/trace"
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)
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type contextKey struct {
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name string
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}
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var tracerKey = contextKey{"tracer"}
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func Tracer(ctx context.Context) trace.Tracer {
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if t := fromContext[contextKey, trace.Tracer](ctx, tracerKey); t != nil {
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return t
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}
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return otel.Tracer("")
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}
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func Span(ctx context.Context, opts ...trace.SpanStartOption) (context.Context, trace.Span) {
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var attrs []attribute.KeyValue
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var name string
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if pc, file, line, ok := runtime.Caller(1); ok {
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if fn := runtime.FuncForPC(pc); fn != nil {
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name = fn.Name()
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}
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attrs = append(attrs,
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attribute.String("pc", fmt.Sprintf("%v", pc)),
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attribute.String("file", file),
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attribute.Int("line", line),
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attribute.String("name", name),
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)
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}
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ctx, span := Tracer(ctx).Start(ctx, name, opts...)
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span.SetAttributes(attrs...)
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return ctx, span
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}
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type SampleRate string
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const (
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SampleAlways SampleRate = "always"
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SampleNever SampleRate = "never"
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)
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func initTracing(ctx context.Context, name string) (context.Context, func() error) {
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res, err := resource.New(ctx,
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resource.WithAttributes(
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semconv.ServiceNameKey.String(name),
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),
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)
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if err != nil {
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log.Println(wrap(err, "failed to create trace resource"))
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return ctx, nil
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}
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exporterAddr := env("EV_TRACE_ENDPOINT", "")
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if exporterAddr == "" {
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return ctx, nil
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}
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traceExporter, err := otlptracehttp.New(ctx,
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otlptracehttp.WithInsecure(),
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otlptracehttp.WithEndpoint(exporterAddr),
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)
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if err != nil {
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log.Println(wrap(err, "failed to create trace exporter"))
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return ctx, nil
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}
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bsp := sdktrace.NewBatchSpanProcessor(traceExporter)
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var sample sdktrace.TracerProviderOption
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sampleRate := SampleRate(env("EV_TRACE_SAMPLE", string(SampleNever)))
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switch sampleRate {
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case "always":
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sample = sdktrace.WithSampler(sdktrace.AlwaysSample())
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case "never":
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sample = sdktrace.WithSampler(sdktrace.NeverSample())
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default:
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if v, err := strconv.Atoi(string(sampleRate)); err != nil {
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sample = sdktrace.WithSampler(sdktrace.NeverSample())
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} else {
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sample = sdktrace.WithSampler(sdktrace.TraceIDRatioBased(float64(v) * 0.01))
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}
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}
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tracerProvider := sdktrace.NewTracerProvider(
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sample,
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sdktrace.WithResource(res),
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sdktrace.WithSpanProcessor(bsp),
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)
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otel.SetTracerProvider(tracerProvider)
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otel.SetTextMapPropagator(propagation.TraceContext{})
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ctx = toContext(ctx, tracerKey, otel.Tracer(name))
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return ctx, func() error {
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ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
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defer cancel()
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defer log.Println("tracer stopped")
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return wrap(tracerProvider.Shutdown(ctx), "failed to shutdown TracerProvider")
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}
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}
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func wrap(err error, s string) error {
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if err != nil {
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return fmt.Errorf(s, err)
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}
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return nil
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}
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func reverse[T any](s []T) {
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first, last := 0, len(s)-1
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for first < last {
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s[first], s[last] = s[last], s[first]
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first++
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last--
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}
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}
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func Htrace(h http.Handler, name string) http.Handler {
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return otelhttp.NewHandler(h, name)
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}
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func toContext[K comparable, V any](ctx context.Context, key K, value V) context.Context {
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return context.WithValue(ctx, key, value)
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}
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func fromContext[K comparable, V any](ctx context.Context, key K) V {
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var empty V
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if v, ok := ctx.Value(key).(V); ok {
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return v
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}
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return empty
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}
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