cloudflared-mirror/tracing/tracing.go

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package tracing
import (
"context"
"errors"
"fmt"
"math"
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"net/http"
"os"
"runtime"
"strings"
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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"
traceID128bitsWidth = 128 / 4
separator = ":"
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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 TracedHTTPRequest struct {
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*http.Request
*cfdTracer
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}
// NewTracedHTTPRequest creates a new tracer for the current HTTP request context.
func NewTracedHTTPRequest(req *http.Request, log *zerolog.Logger) *TracedHTTPRequest {
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ctx, exists := extractTrace(req)
if !exists {
return &TracedHTTPRequest{req, &cfdTracer{trace.NewNoopTracerProvider(), &NoopOtlpClient{}, log}}
}
return &TracedHTTPRequest{req.WithContext(ctx), newCfdTracer(ctx, log)}
}
func (tr *TracedHTTPRequest) ToTracedContext() *TracedContext {
return &TracedContext{tr.Context(), tr.cfdTracer}
}
type TracedContext struct {
context.Context
*cfdTracer
}
// NewTracedContext creates a new tracer for the current context.
func NewTracedContext(ctx context.Context, traceContext string, log *zerolog.Logger) *TracedContext {
ctx, exists := extractTraceFromString(ctx, traceContext)
if !exists {
return &TracedContext{ctx, &cfdTracer{trace.NewNoopTracerProvider(), &NoopOtlpClient{}, log}}
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}
return &TracedContext{ctx, newCfdTracer(ctx, log)}
}
type cfdTracer struct {
trace.TracerProvider
exporter InMemoryClient
log *zerolog.Logger
}
// NewCfdTracer creates a new tracer for the current request context.
func newCfdTracer(ctx context.Context, log *zerolog.Logger) *cfdTracer {
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mc := new(InMemoryOtlpClient)
exp, err := otlptrace.New(ctx, mc)
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if err != nil {
return &cfdTracer{trace.NewNoopTracerProvider(), &NoopOtlpClient{}, log}
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}
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 &cfdTracer{tp, mc, log}
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}
func (cft *cfdTracer) Tracer() trace.Tracer {
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return cft.TracerProvider.Tracer(tracerInstrumentName)
}
// GetSpans returns the spans as base64 encoded string of protobuf otlp traces.
func (cft *cfdTracer) GetSpans() (enc string) {
enc, err := cft.exporter.Spans()
switch err {
case nil:
break
case errNoTraces:
cft.log.Trace().Err(err).Msgf("expected traces to be available")
return
case errNoopTracer:
return // noop tracer has no traces
default:
cft.log.Debug().Err(err)
return
}
return
}
// GetProtoSpans returns the spans as the otlp traces in protobuf byte array.
func (cft *cfdTracer) GetProtoSpans() (proto []byte) {
proto, err := cft.exporter.ExportProtoSpans()
switch err {
case nil:
break
case errNoTraces:
cft.log.Trace().Err(err).Msgf("expected traces to be available")
return
case errNoopTracer:
return // noop tracer has no traces
default:
cft.log.Debug().Err(err)
return
}
return
}
// AddSpans assigns spans as base64 encoded protobuf otlp traces to provided
// HTTP headers.
func (cft *cfdTracer) AddSpans(headers http.Header) {
if headers == nil {
return
}
enc := cft.GetSpans()
// No need to add header if no traces
if enc == "" {
return
}
headers[CanonicalCloudflaredTracingHeader] = []string{enc}
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}
// End will set the OK status for the span and then end it.
func End(span trace.Span) {
endSpan(span, -1, codes.Ok, nil)
}
// 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()
}
// extractTraceFromString will extract the trace information from the provided
// propagated trace string context.
func extractTraceFromString(ctx context.Context, trace string) (context.Context, bool) {
if trace == "" {
return ctx, false
}
// Jaeger specific separator
parts := strings.Split(trace, separator)
if len(parts) != 4 {
return ctx, false
}
if parts[0] == "" {
return ctx, false
}
// Correctly left pad the trace to a length of 32
if len(parts[0]) < traceID128bitsWidth {
left := traceID128bitsWidth - len(parts[0])
parts[0] = strings.Repeat("0", left) + parts[0]
trace = strings.Join(parts, separator)
}
// Override the 'cf-trace-id' as 'uber-trace-id' so the jaeger propagator can extract it.
traceHeader := map[string]string{TracerContextNameOverride: trace}
remoteCtx := otel.GetTextMapPropagator().Extract(ctx, propagation.MapCarrier(traceHeader))
return remoteCtx, true
}
// 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
}
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remoteCtx := otel.GetTextMapPropagator().Extract(req.Context(), propagation.MapCarrier(traceHeader))
return remoteCtx, true
}
func NewNoopSpan() trace.Span {
return trace.SpanFromContext(nil)
}