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W3CBaggagePropagator.ts
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W3CBaggagePropagator.ts
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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
*
* https://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.
*/
import {
BaggageEntry,
Context,
propagation,
TextMapGetter,
TextMapPropagator,
TextMapSetter,
} from '@opentelemetry/api';
import { isTracingSuppressed } from '../../trace/suppress-tracing';
import {
BAGGAGE_HEADER,
BAGGAGE_ITEMS_SEPARATOR,
BAGGAGE_MAX_NAME_VALUE_PAIRS,
BAGGAGE_MAX_PER_NAME_VALUE_PAIRS
} from '../constants';
import {
getKeyPairs,
parsePairKeyValue,
serializeKeyPairs
} from '../utils';
/**
* Propagates {@link Baggage} through Context format propagation.
*
* Based on the Baggage specification:
* https://w3c.github.io/baggage/
*/
export class W3CBaggagePropagator implements TextMapPropagator {
inject(context: Context, carrier: unknown, setter: TextMapSetter): void {
const baggage = propagation.getBaggage(context);
if (!baggage || isTracingSuppressed(context)) return;
const keyPairs = getKeyPairs(baggage)
.filter((pair: string) => {
return pair.length <= BAGGAGE_MAX_PER_NAME_VALUE_PAIRS;
})
.slice(0, BAGGAGE_MAX_NAME_VALUE_PAIRS);
const headerValue = serializeKeyPairs(keyPairs);
if (headerValue.length > 0) {
setter.set(carrier, BAGGAGE_HEADER, headerValue);
}
}
extract(context: Context, carrier: unknown, getter: TextMapGetter): Context {
const headerValue: string = getter.get(carrier, BAGGAGE_HEADER) as string;
if (!headerValue) return context;
const baggage: Record<string, BaggageEntry> = {};
if (headerValue.length === 0) {
return context;
}
const pairs = headerValue.split(BAGGAGE_ITEMS_SEPARATOR);
pairs.forEach(entry => {
const keyPair = parsePairKeyValue(entry);
if (keyPair) {
const baggageEntry: BaggageEntry = { value: keyPair.value };
if (keyPair.metadata) {
baggageEntry.metadata = keyPair.metadata;
}
baggage[keyPair.key] = baggageEntry;
}
});
if (Object.entries(baggage).length === 0) {
return context;
}
return propagation.setBaggage(context, propagation.createBaggage(baggage));
}
fields(): string[] {
return [BAGGAGE_HEADER];
}
}