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opentelemetry-go/api/baggage/baggage_propagator.go
Anthony Mirabella 06689a01bd
Rename CorrelationContext to Baggage (#1142)
* Rename 'correlation' to 'baggage'

* Rename CorrelationContext progator to Baggage

* Update CHANGELOG
2020-09-09 14:13:37 -04:00

119 lines
3.5 KiB
Go

// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package baggage
import (
"context"
"net/url"
"strings"
"go.opentelemetry.io/otel/api/propagation"
"go.opentelemetry.io/otel/label"
)
// Temporary header name until W3C finalizes format.
// https://github.com/open-telemetry/opentelemetry-specification/blob/18b2752ebe6c7f0cdd8c7b2bcbdceb0ae3f5ad95/specification/correlationcontext/api.md#header-name
const baggageHeader = "otcorrelations"
// Baggage propagates Key:Values in W3C CorrelationContext
// format.
// nolint:golint
type Baggage struct{}
var _ propagation.HTTPPropagator = Baggage{}
// DefaultHTTPPropagator returns the default context correlation HTTP
// propagator.
func DefaultHTTPPropagator() propagation.HTTPPropagator {
return Baggage{}
}
// Inject implements HTTPInjector.
func (b Baggage) Inject(ctx context.Context, supplier propagation.HTTPSupplier) {
baggageMap := MapFromContext(ctx)
firstIter := true
var headerValueBuilder strings.Builder
baggageMap.Foreach(func(kv label.KeyValue) bool {
if !firstIter {
headerValueBuilder.WriteRune(',')
}
firstIter = false
headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace((string)(kv.Key))))
headerValueBuilder.WriteRune('=')
headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace(kv.Value.Emit())))
return true
})
if headerValueBuilder.Len() > 0 {
headerString := headerValueBuilder.String()
supplier.Set(baggageHeader, headerString)
}
}
// Extract implements HTTPExtractor.
func (b Baggage) Extract(ctx context.Context, supplier propagation.HTTPSupplier) context.Context {
baggage := supplier.Get(baggageHeader)
if baggage == "" {
return ctx
}
baggageValues := strings.Split(baggage, ",")
keyValues := make([]label.KeyValue, 0, len(baggageValues))
for _, baggageValue := range baggageValues {
valueAndProps := strings.Split(baggageValue, ";")
if len(valueAndProps) < 1 {
continue
}
nameValue := strings.Split(valueAndProps[0], "=")
if len(nameValue) < 2 {
continue
}
name, err := url.QueryUnescape(nameValue[0])
if err != nil {
continue
}
trimmedName := strings.TrimSpace(name)
value, err := url.QueryUnescape(nameValue[1])
if err != nil {
continue
}
trimmedValue := strings.TrimSpace(value)
// TODO (skaris): properties defiend https://w3c.github.io/correlation-context/, are currently
// just put as part of the value.
var trimmedValueWithProps strings.Builder
trimmedValueWithProps.WriteString(trimmedValue)
for _, prop := range valueAndProps[1:] {
trimmedValueWithProps.WriteRune(';')
trimmedValueWithProps.WriteString(prop)
}
keyValues = append(keyValues, label.String(trimmedName, trimmedValueWithProps.String()))
}
if len(keyValues) > 0 {
// Only update the context if valid values were found
return ContextWithMap(ctx, NewMap(MapUpdate{
MultiKV: keyValues,
}))
}
return ctx
}
// GetAllKeys implements HTTPPropagator.
func (b Baggage) GetAllKeys() []string {
return []string{baggageHeader}
}