112 lines
3.4 KiB
Go
112 lines
3.4 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 propagation // import "go.opentelemetry.io/otel/propagation"
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import (
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"context"
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"net/url"
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"strings"
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"go.opentelemetry.io/otel/internal/baggage"
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"go.opentelemetry.io/otel/label"
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)
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const baggageHeader = "baggage"
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// Baggage is a propagator that supports the W3C Baggage format.
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//
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// This propagates user-defined baggage associated with a trace. The complete
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// specification is defined at https://w3c.github.io/baggage/.
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type Baggage struct{}
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var _ TextMapPropagator = Baggage{}
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// Inject sets baggage key-values from ctx into the carrier.
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func (b Baggage) Inject(ctx context.Context, carrier TextMapCarrier) {
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baggageMap := baggage.MapFromContext(ctx)
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firstIter := true
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var headerValueBuilder strings.Builder
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baggageMap.Foreach(func(kv label.KeyValue) bool {
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if !firstIter {
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headerValueBuilder.WriteRune(',')
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}
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firstIter = false
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headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace((string)(kv.Key))))
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headerValueBuilder.WriteRune('=')
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headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace(kv.Value.Emit())))
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return true
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})
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if headerValueBuilder.Len() > 0 {
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headerString := headerValueBuilder.String()
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carrier.Set(baggageHeader, headerString)
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}
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}
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// Extract returns a copy of parent with the baggage from the carrier added.
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func (b Baggage) Extract(parent context.Context, carrier TextMapCarrier) context.Context {
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bVal := carrier.Get(baggageHeader)
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if bVal == "" {
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return parent
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}
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baggageValues := strings.Split(bVal, ",")
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keyValues := make([]label.KeyValue, 0, len(baggageValues))
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for _, baggageValue := range baggageValues {
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valueAndProps := strings.Split(baggageValue, ";")
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if len(valueAndProps) < 1 {
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continue
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}
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nameValue := strings.Split(valueAndProps[0], "=")
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if len(nameValue) < 2 {
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continue
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}
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name, err := url.QueryUnescape(nameValue[0])
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if err != nil {
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continue
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}
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trimmedName := strings.TrimSpace(name)
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value, err := url.QueryUnescape(nameValue[1])
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if err != nil {
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continue
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}
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trimmedValue := strings.TrimSpace(value)
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// TODO (skaris): properties defiend https://w3c.github.io/correlation-context/, are currently
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// just put as part of the value.
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var trimmedValueWithProps strings.Builder
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trimmedValueWithProps.WriteString(trimmedValue)
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for _, prop := range valueAndProps[1:] {
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trimmedValueWithProps.WriteRune(';')
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trimmedValueWithProps.WriteString(prop)
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}
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keyValues = append(keyValues, label.String(trimmedName, trimmedValueWithProps.String()))
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}
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if len(keyValues) > 0 {
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// Only update the context if valid values were found
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return baggage.ContextWithMap(parent, baggage.NewMap(baggage.MapUpdate{
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MultiKV: keyValues,
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}))
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}
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return parent
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}
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// Fields returns the keys who's values are set with Inject.
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func (b Baggage) Fields() []string {
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return []string{baggageHeader}
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}
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