/
correlation_context_propagator.go
112 lines (99 loc) · 3.56 KB
/
correlation_context_propagator.go
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// 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 correlation
import (
"context"
"net/url"
"strings"
"go.opentelemetry.io/otel/api/kv"
"go.opentelemetry.io/otel/api/propagation"
)
// Temporary header name until W3C finalizes format.
// https://github.com/open-telemetry/opentelemetry-specification/blob/18b2752ebe6c7f0cdd8c7b2bcbdceb0ae3f5ad95/specification/correlationcontext/api.md#header-name
const correlationContextHeader = "otcorrelations"
// CorrelationContext propagates Key:Values in W3C CorrelationContext
// format.
// nolint:golint
type CorrelationContext struct{}
var _ propagation.HTTPPropagator = CorrelationContext{}
// DefaultHTTPPropagator returns the default context correlation HTTP
// propagator.
func DefaultHTTPPropagator() propagation.HTTPPropagator {
return CorrelationContext{}
}
// Inject implements HTTPInjector.
func (CorrelationContext) Inject(ctx context.Context, supplier propagation.HTTPSupplier) {
correlationCtx := MapFromContext(ctx)
firstIter := true
var headerValueBuilder strings.Builder
correlationCtx.Foreach(func(kv kv.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(correlationContextHeader, headerString)
}
}
// Extract implements HTTPExtractor.
func (CorrelationContext) Extract(ctx context.Context, supplier propagation.HTTPSupplier) context.Context {
correlationContext := supplier.Get(correlationContextHeader)
if correlationContext == "" {
return ContextWithMap(ctx, NewEmptyMap())
}
contextValues := strings.Split(correlationContext, ",")
keyValues := make([]kv.KeyValue, 0, len(contextValues))
for _, contextValue := range contextValues {
valueAndProps := strings.Split(contextValue, ";")
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, kv.Key(trimmedName).String(trimmedValueWithProps.String()))
}
return ContextWithMap(ctx, NewMap(MapUpdate{
MultiKV: keyValues,
}))
}
// GetAllKeys implements HTTPPropagator.
func (CorrelationContext) GetAllKeys() []string {
return []string{correlationContextHeader}
}