/
baggage.go
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/
baggage.go
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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package propagation // import "go.opentelemetry.io/otel/propagation"
import (
"context"
"go.opentelemetry.io/otel/baggage"
)
const baggageHeader = "baggage"
// Baggage is a propagator that supports the W3C Baggage format.
//
// This propagates user-defined baggage associated with a trace. The complete
// specification is defined at https://www.w3.org/TR/baggage/.
type Baggage struct{}
var _ TextMapPropagator = Baggage{}
// Inject sets baggage key-values from ctx into the carrier.
func (b Baggage) Inject(ctx context.Context, carrier TextMapCarrier) {
bStr := baggage.FromContext(ctx).String()
if bStr != "" {
carrier.Set(baggageHeader, bStr)
}
}
// Extract returns a copy of parent with the baggage from the carrier added.
func (b Baggage) Extract(parent context.Context, carrier TextMapCarrier) context.Context {
bStr := carrier.Get(baggageHeader)
if bStr == "" {
return parent
}
bag, err := baggage.Parse(bStr)
if err != nil {
return parent
}
return baggage.ContextWithBaggage(parent, bag)
}
// Fields returns the keys who's values are set with Inject.
func (b Baggage) Fields() []string {
return []string{baggageHeader}
}