mirror of
https://github.com/open-telemetry/opentelemetry-go.git
synced 2024-12-16 10:19:23 +02:00
217 lines
4.8 KiB
Go
217 lines
4.8 KiB
Go
// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package trace
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import (
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"context"
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"fmt"
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"strings"
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"go.opentelemetry.io/otel/api/propagation"
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)
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const (
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B3SingleHeader = "X-B3"
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B3DebugFlagHeader = "X-B3-Flags"
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B3TraceIDHeader = "X-B3-TraceId"
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B3SpanIDHeader = "X-B3-SpanId"
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B3SampledHeader = "X-B3-Sampled"
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B3ParentSpanIDHeader = "X-B3-ParentSpanId"
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b3TraceIDPadding = "0000000000000000"
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)
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// B3 propagator serializes SpanContext to/from B3 Headers.
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// This propagator supports both version of B3 headers,
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// 1. Single Header :
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// X-B3: {TraceId}-{SpanId}-{SamplingState}-{ParentSpanId}
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// 2. Multiple Headers:
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// X-B3-TraceId: {TraceId}
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// X-B3-ParentSpanId: {ParentSpanId}
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// X-B3-SpanId: {SpanId}
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// X-B3-Sampled: {SamplingState}
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// X-B3-Flags: {DebugFlag}
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//
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// If SingleHeader is set to true then X-B3 header is used to inject and extract. Otherwise,
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// separate headers are used to inject and extract.
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type B3 struct {
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SingleHeader bool
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}
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var _ propagation.HTTPPropagator = B3{}
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func (b3 B3) Inject(ctx context.Context, supplier propagation.HTTPSupplier) {
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sc := SpanFromContext(ctx).SpanContext()
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if !sc.IsValid() {
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return
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}
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if b3.SingleHeader {
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sampled := sc.TraceFlags & FlagsSampled
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supplier.Set(B3SingleHeader,
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fmt.Sprintf("%s-%s-%.1d", sc.TraceID, sc.SpanID, sampled))
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} else {
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supplier.Set(B3TraceIDHeader, sc.TraceID.String())
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supplier.Set(B3SpanIDHeader, sc.SpanID.String())
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var sampled string
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if sc.IsSampled() {
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sampled = "1"
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} else {
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sampled = "0"
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}
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supplier.Set(B3SampledHeader, sampled)
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}
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}
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// Extract retrieves B3 Headers from the supplier
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func (b3 B3) Extract(ctx context.Context, supplier propagation.HTTPSupplier) context.Context {
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var sc SpanContext
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if b3.SingleHeader {
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sc = b3.extractSingleHeader(supplier)
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} else {
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sc = b3.extract(supplier)
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}
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if !sc.IsValid() {
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return ctx
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}
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return ContextWithRemoteSpanContext(ctx, sc)
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}
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func fixB3TID(in string) string {
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if len(in) == 16 {
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in = b3TraceIDPadding + in
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}
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return in
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}
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func (b3 B3) extract(supplier propagation.HTTPSupplier) SpanContext {
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tid, err := IDFromHex(fixB3TID(supplier.Get(B3TraceIDHeader)))
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if err != nil {
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return EmptySpanContext()
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}
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sid, err := SpanIDFromHex(supplier.Get(B3SpanIDHeader))
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if err != nil {
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return EmptySpanContext()
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}
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sampled, ok := b3.extractSampledState(supplier.Get(B3SampledHeader))
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if !ok {
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return EmptySpanContext()
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}
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debug, ok := b3.extracDebugFlag(supplier.Get(B3DebugFlagHeader))
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if !ok {
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return EmptySpanContext()
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}
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if debug == FlagsSampled {
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sampled = FlagsSampled
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}
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sc := SpanContext{
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TraceID: tid,
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SpanID: sid,
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TraceFlags: sampled,
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}
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if !sc.IsValid() {
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return EmptySpanContext()
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}
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return sc
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}
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func (b3 B3) extractSingleHeader(supplier propagation.HTTPSupplier) SpanContext {
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h := supplier.Get(B3SingleHeader)
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if h == "" || h == "0" {
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return EmptySpanContext()
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}
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sc := SpanContext{}
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parts := strings.Split(h, "-")
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l := len(parts)
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if l > 4 {
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return EmptySpanContext()
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}
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if l < 2 {
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return EmptySpanContext()
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}
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var err error
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sc.TraceID, err = IDFromHex(fixB3TID(parts[0]))
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if err != nil {
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return EmptySpanContext()
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}
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sc.SpanID, err = SpanIDFromHex(parts[1])
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if err != nil {
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return EmptySpanContext()
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}
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if l > 2 {
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var ok bool
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sc.TraceFlags, ok = b3.extractSampledState(parts[2])
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if !ok {
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return EmptySpanContext()
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}
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}
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if l == 4 {
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_, err = SpanIDFromHex(parts[3])
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if err != nil {
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return EmptySpanContext()
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}
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}
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if !sc.IsValid() {
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return EmptySpanContext()
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}
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return sc
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}
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// extractSampledState parses the value of the X-B3-Sampled b3Header.
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func (b3 B3) extractSampledState(sampled string) (flag byte, ok bool) {
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switch sampled {
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case "", "0":
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return 0, true
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case "1":
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return FlagsSampled, true
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case "true":
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if !b3.SingleHeader {
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return FlagsSampled, true
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}
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case "d":
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if b3.SingleHeader {
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return FlagsSampled, true
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}
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}
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return 0, false
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}
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// extracDebugFlag parses the value of the X-B3-Sampled b3Header.
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func (b3 B3) extracDebugFlag(debug string) (flag byte, ok bool) {
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switch debug {
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case "", "0":
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return 0, true
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case "1":
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return FlagsSampled, true
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}
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return 0, false
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}
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func (b3 B3) GetAllKeys() []string {
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if b3.SingleHeader {
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return []string{B3SingleHeader}
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}
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return []string{B3TraceIDHeader, B3SpanIDHeader, B3SampledHeader}
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}
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