@opentelemetry/propagator-b3
Version:
OpenTelemetry B3 propagator provides context propagation for systems that are using the B3 header format
75 lines • 3.03 kB
JavaScript
/*
* 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 { isSpanContextValid, isValidSpanId, isValidTraceId, trace, TraceFlags, } from '@opentelemetry/api';
import { isTracingSuppressed } from '@opentelemetry/core';
import { B3_DEBUG_FLAG_KEY } from './common';
import { B3_CONTEXT_HEADER } from './constants';
const B3_CONTEXT_REGEX = /((?:[0-9a-f]{16}){1,2})-([0-9a-f]{16})(?:-([01d](?![0-9a-f])))?(?:-([0-9a-f]{16}))?/;
const PADDING = '0'.repeat(16);
const SAMPLED_VALUES = new Set(['d', '1']);
const DEBUG_STATE = 'd';
function convertToTraceId128(traceId) {
return traceId.length === 32 ? traceId : `${PADDING}${traceId}`;
}
function convertToTraceFlags(samplingState) {
if (samplingState && SAMPLED_VALUES.has(samplingState)) {
return TraceFlags.SAMPLED;
}
return TraceFlags.NONE;
}
/**
* Propagator for the B3 single-header HTTP format.
* Based on: https://github.com/openzipkin/b3-propagation
*/
export class B3SinglePropagator {
inject(context, carrier, setter) {
const spanContext = trace.getSpanContext(context);
if (!spanContext ||
!isSpanContextValid(spanContext) ||
isTracingSuppressed(context))
return;
const samplingState = context.getValue(B3_DEBUG_FLAG_KEY) || spanContext.traceFlags & 0x1;
const value = `${spanContext.traceId}-${spanContext.spanId}-${samplingState}`;
setter.set(carrier, B3_CONTEXT_HEADER, value);
}
extract(context, carrier, getter) {
const header = getter.get(carrier, B3_CONTEXT_HEADER);
const b3Context = Array.isArray(header) ? header[0] : header;
if (typeof b3Context !== 'string')
return context;
const match = b3Context.match(B3_CONTEXT_REGEX);
if (!match)
return context;
const [, extractedTraceId, spanId, samplingState] = match;
const traceId = convertToTraceId128(extractedTraceId);
if (!isValidTraceId(traceId) || !isValidSpanId(spanId))
return context;
const traceFlags = convertToTraceFlags(samplingState);
if (samplingState === DEBUG_STATE) {
context = context.setValue(B3_DEBUG_FLAG_KEY, samplingState);
}
return trace.setSpanContext(context, {
traceId,
spanId,
isRemote: true,
traceFlags,
});
}
fields() {
return [B3_CONTEXT_HEADER];
}
}
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