cloudflared-mirror/tracing/tracing.go

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package tracing
import (
"context"
"errors"
"fmt"
"math"
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"net/http"
"os"
"runtime"
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"github.com/rs/zerolog"
otelContrib "go.opentelemetry.io/contrib/propagators/jaeger"
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"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"
IntCloudflaredTracingHeader = "cf-int-cloudflared-tracing"
MaxErrorDescriptionLen = 100
traceHttpStatusCodeKey = "upstreamStatusCode"
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)
var (
CanonicalCloudflaredTracingHeader = http.CanonicalHeaderKey(IntCloudflaredTracingHeader)
Http2TransportAttribute = trace.WithAttributes(transportAttributeKey.String("http2"))
QuicTransportAttribute = trace.WithAttributes(transportAttributeKey.String("quic"))
HostOSAttribute = semconv.HostTypeKey.String(runtime.GOOS)
HostArchAttribute = semconv.HostArchKey.String(runtime.GOARCH)
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otelVersionAttribute attribute.KeyValue
hostnameAttribute attribute.KeyValue
cloudflaredVersionAttribute attribute.KeyValue
serviceAttribute = semconv.ServiceNameKey.String(service)
transportAttributeKey = attribute.Key("transport")
otelVersionAttributeKey = attribute.Key("jaeger.version")
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errNoopTracerProvider = errors.New("noop tracer provider records no spans")
)
func init() {
// Register the jaeger propagator globally.
otel.SetTextMapPropagator(otelContrib.Jaeger{})
otelVersionAttribute = otelVersionAttributeKey.String(fmt.Sprintf("go-otel-%s", otel.Version()))
if hostname, err := os.Hostname(); err == nil {
hostnameAttribute = attribute.String("hostname", hostname)
}
}
func Init(version string) {
cloudflaredVersionAttribute = semconv.ProcessRuntimeVersionKey.String(version)
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}
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,
serviceAttribute,
otelVersionAttribute,
hostnameAttribute,
cloudflaredVersionAttribute,
HostOSAttribute,
HostArchAttribute,
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)),
)
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) AddSpans(headers http.Header, log *zerolog.Logger) {
if headers == nil {
log.Error().Msgf("provided headers map is nil")
return
}
enc, err := cft.exporter.Spans()
switch err {
case nil:
break
case errNoTraces:
log.Error().Err(err).Msgf("expected traces to be available")
return
case errNoopTracer:
return // noop tracer has no traces
default:
log.Error().Err(err)
return
}
// No need to add header if no traces
if enc == "" {
log.Error().Msgf("no traces provided and no error from exporter")
return
}
headers[CanonicalCloudflaredTracingHeader] = []string{enc}
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}
// EndWithErrorStatus will set a status for the span and then end it.
func EndWithErrorStatus(span trace.Span, err error) {
endSpan(span, -1, codes.Error, err)
}
// EndWithStatusCode will set a status for the span and then end it.
func EndWithStatusCode(span trace.Span, statusCode int) {
endSpan(span, statusCode, codes.Ok, nil)
}
// EndWithErrorStatus will set a status for the span and then end it.
func endSpan(span trace.Span, upstreamStatusCode int, spanStatusCode codes.Code, err error) {
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if span == nil {
return
}
if upstreamStatusCode > 0 {
span.SetAttributes(attribute.Int(traceHttpStatusCodeKey, upstreamStatusCode))
}
// add error to status buf cap description
errDescription := ""
if err != nil {
errDescription = err.Error()
l := int(math.Min(float64(len(errDescription)), MaxErrorDescriptionLen))
errDescription = errDescription[:l]
}
span.SetStatus(spanStatusCode, errDescription)
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span.End()
}
// extractTrace attempts to check for a cf-trace-id from a request and return the
// trace context with the provided http.Request.
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func extractTrace(req *http.Request) (context.Context, bool) {
// Only add tracing for requests with appropriately tagged headers
remoteTraces := req.Header.Values(TracerContextName)
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if len(remoteTraces) <= 0 {
// Strip the cf-trace-id header
req.Header.Del(TracerContextName)
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return nil, false
}
traceHeader := map[string]string{}
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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
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}
// Strip the cf-trace-id header
req.Header.Del(TracerContextName)
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if traceHeader[TracerContextNameOverride] == "" {
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return nil, false
}
remoteCtx := otel.GetTextMapPropagator().Extract(req.Context(), propagation.MapCarrier(traceHeader))
return remoteCtx, true
}