162 lines
4.7 KiB
Go
162 lines
4.7 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 jaeger
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import (
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"context"
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"errors"
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"fmt"
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"strconv"
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"strings"
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"go.opentelemetry.io/otel/propagation"
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"go.opentelemetry.io/otel/trace"
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)
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const (
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jaegerHeader = "uber-trace-id"
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separator = ":"
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traceID64bitsWidth = 64 / 4
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traceID128bitsWidth = 128 / 4
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spanIDWidth = 64 / 4
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traceIDPadding = "0000000000000000"
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flagsDebug = 0x02
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flagsSampled = 0x01
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flagsNotSampled = 0x00
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deprecatedParentSpanID = "0"
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)
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var (
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empty = trace.SpanContext{}
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errMalformedTraceContextVal = errors.New("header value of uber-trace-id should contain four different part separated by : ")
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errInvalidTraceIDLength = errors.New("invalid trace id length, must be either 16 or 32")
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errMalformedTraceID = errors.New("cannot decode trace id from header, should be a string of hex, lowercase trace id can't be all zero")
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errInvalidSpanIDLength = errors.New("invalid span id length, must be 16")
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errMalformedSpanID = errors.New("cannot decode span id from header, should be a string of hex, lowercase span id can't be all zero")
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errMalformedFlag = errors.New("cannot decode flag")
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)
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// Jaeger propagator serializes SpanContext to/from Jaeger Headers
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//
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// Jaeger format:
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//
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// uber-trace-id: {trace-id}:{span-id}:{parent-span-id}:{flags}
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type Jaeger struct{}
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var _ propagation.TextMapPropagator = &Jaeger{}
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// Inject injects a context to the carrier following jaeger format.
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// The parent span ID is set to an dummy parent span id as the most implementations do.
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func (jaeger Jaeger) Inject(ctx context.Context, carrier propagation.TextMapCarrier) {
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sc := trace.SpanFromContext(ctx).SpanContext()
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headers := []string{}
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if !sc.TraceID().IsValid() || !sc.SpanID().IsValid() {
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return
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}
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headers = append(headers, sc.TraceID().String(), sc.SpanID().String(), deprecatedParentSpanID)
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if debugFromContext(ctx) {
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headers = append(headers, fmt.Sprintf("%x", flagsDebug|flagsSampled))
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} else if sc.IsSampled() {
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headers = append(headers, fmt.Sprintf("%x", flagsSampled))
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} else {
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headers = append(headers, fmt.Sprintf("%x", flagsNotSampled))
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}
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carrier.Set(jaegerHeader, strings.Join(headers, separator))
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}
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// Extract extracts a context from the carrier if it contains Jaeger headers.
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func (jaeger Jaeger) Extract(ctx context.Context, carrier propagation.TextMapCarrier) context.Context {
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// extract tracing information
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if h := carrier.Get(jaegerHeader); h != "" {
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ctx, sc, err := extract(ctx, h)
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if err == nil && sc.IsValid() {
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return trace.ContextWithRemoteSpanContext(ctx, sc)
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}
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}
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return ctx
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}
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func extract(ctx context.Context, headerVal string) (context.Context, trace.SpanContext, error) {
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var (
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scc = trace.SpanContextConfig{}
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err error
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)
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parts := strings.Split(headerVal, separator)
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if len(parts) != 4 {
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return ctx, empty, errMalformedTraceContextVal
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}
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// extract trace ID
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if parts[0] != "" {
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id := parts[0]
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if len(id) != traceID128bitsWidth && len(id) != traceID64bitsWidth {
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return ctx, empty, errInvalidTraceIDLength
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}
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// padding when length is 16
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if len(id) == traceID64bitsWidth {
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id = traceIDPadding + id
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}
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scc.TraceID, err = trace.TraceIDFromHex(id)
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if err != nil {
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return ctx, empty, errMalformedTraceID
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}
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}
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// extract span ID
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if parts[1] != "" {
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id := parts[1]
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if len(id) != spanIDWidth {
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return ctx, empty, errInvalidSpanIDLength
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}
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scc.SpanID, err = trace.SpanIDFromHex(id)
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if err != nil {
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return ctx, empty, errMalformedSpanID
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}
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}
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// skip third part as it is deprecated
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// extract flag
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if parts[3] != "" {
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flagStr := parts[3]
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flag, err := strconv.ParseInt(flagStr, 16, 64)
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if err != nil {
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return ctx, empty, errMalformedFlag
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}
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if flag&flagsSampled == flagsSampled {
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// if sample bit is set, we check if debug bit is also set
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if flag&flagsDebug == flagsDebug {
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scc.TraceFlags |= trace.FlagsSampled
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ctx = withDebug(ctx, true)
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} else {
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scc.TraceFlags |= trace.FlagsSampled
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}
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}
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// ignore other bit, including firehose since we don't have corresponding flag in trace context.
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}
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return ctx, trace.NewSpanContext(scc), nil
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}
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func (jaeger Jaeger) Fields() []string {
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return []string{jaegerHeader}
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}
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