cloudflared-mirror/tracing/tracing.go

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2022-04-06 23:20:29 +00:00
package tracing
import (
"context"
"errors"
"net/http"
otelContrib "go.opentelemetry.io/contrib/propagators/Jaeger"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/sdk/resource"
tracesdk "go.opentelemetry.io/otel/sdk/trace"
semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
"go.opentelemetry.io/otel/trace"
)
const (
service = "cloudflared"
tracerInstrumentName = "origin"
tracerContextName = "cf-trace-id"
tracerContextNameOverride = "uber-trace-id"
)
var (
Http2TransportAttribute = trace.WithAttributes(TransportAttributeKey.String("http2"))
QuicTransportAttribute = trace.WithAttributes(TransportAttributeKey.String("quic"))
TransportAttributeKey = attribute.Key("transport")
TrafficAttributeKey = attribute.Key("traffic")
errNoopTracerProvider = errors.New("noop tracer provider records no spans")
)
func init() {
// Register the jaeger propagator globally.
otel.SetTextMapPropagator(otelContrib.Jaeger{})
}
type TracedRequest struct {
*http.Request
trace.TracerProvider
exporter InMemoryClient
}
// NewTracedRequest creates a new tracer for the current request context.
func NewTracedRequest(req *http.Request) *TracedRequest {
ctx, exists := extractTrace(req)
if !exists {
return &TracedRequest{req, trace.NewNoopTracerProvider(), &NoopOtlpClient{}}
}
mc := new(InMemoryOtlpClient)
exp, err := otlptrace.New(req.Context(), mc)
if err != nil {
return &TracedRequest{req, trace.NewNoopTracerProvider(), &NoopOtlpClient{}}
}
tp := tracesdk.NewTracerProvider(
// We want to dump to in-memory exporter immediately
tracesdk.WithSyncer(exp),
// Record information about this application in a Resource.
tracesdk.WithResource(resource.NewWithAttributes(
semconv.SchemaURL,
semconv.ServiceNameKey.String(service),
)),
)
return &TracedRequest{req.WithContext(ctx), tp, mc}
}
func (cft *TracedRequest) Tracer() trace.Tracer {
return cft.TracerProvider.Tracer(tracerInstrumentName)
}
// Spans returns the spans as base64 encoded protobuf otlp traces.
func (cft *TracedRequest) Spans() (string, error) {
return cft.exporter.Spans()
}
// EndWithStatus will set a status for the span and then end it.
func EndWithStatus(span trace.Span, code codes.Code, status string) {
if span == nil {
return
}
span.SetStatus(code, status)
span.End()
}
// extractTrace attempts to check for a cf-trace-id from a request header.
func extractTrace(req *http.Request) (context.Context, bool) {
// Only add tracing for requests with appropriately tagged headers
remoteTraces := req.Header.Values(tracerContextName)
if len(remoteTraces) <= 0 {
// Strip the cf-trace-id header
req.Header.Del(tracerContextName)
return nil, false
}
traceHeader := make(map[string]string, 1)
for _, t := range remoteTraces {
// Override the 'cf-trace-id' as 'uber-trace-id' so the jaeger propagator can extract it.
// Last entry wins if multiple provided
traceHeader[tracerContextNameOverride] = t
}
// Strip the cf-trace-id header
req.Header.Del(tracerContextName)
if traceHeader[tracerContextNameOverride] == "" {
return nil, false
}
remoteCtx := otel.GetTextMapPropagator().Extract(req.Context(), propagation.MapCarrier(traceHeader))
return remoteCtx, true
}