@opentelemetry/propagator-b3
Version:
OpenTelemetry B3 propagator provides context propagation for systems that are using the B3 header format
106 lines • 3.93 kB
JavaScript
/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/
import { isSpanContextValid, isValidSpanId, isValidTraceId, trace, TraceFlags, } from '@opentelemetry/api';
import { isTracingSuppressed } from '@opentelemetry/core';
import { B3_DEBUG_FLAG_KEY } from './common';
import { X_B3_FLAGS, X_B3_PARENT_SPAN_ID, X_B3_SAMPLED, X_B3_SPAN_ID, X_B3_TRACE_ID, } from './constants';
const VALID_SAMPLED_VALUES = new Set([true, 'true', 'True', '1', 1]);
const VALID_UNSAMPLED_VALUES = new Set([false, 'false', 'False', '0', 0]);
function isValidSampledValue(sampled) {
return sampled === TraceFlags.SAMPLED || sampled === TraceFlags.NONE;
}
function parseHeader(header) {
return Array.isArray(header) ? header[0] : header;
}
function getHeaderValue(carrier, getter, key) {
const header = getter.get(carrier, key);
return parseHeader(header);
}
function getTraceId(carrier, getter) {
const traceId = getHeaderValue(carrier, getter, X_B3_TRACE_ID);
if (typeof traceId === 'string') {
return traceId.padStart(32, '0');
}
return '';
}
function getSpanId(carrier, getter) {
const spanId = getHeaderValue(carrier, getter, X_B3_SPAN_ID);
if (typeof spanId === 'string') {
return spanId;
}
return '';
}
function getDebug(carrier, getter) {
const debug = getHeaderValue(carrier, getter, X_B3_FLAGS);
return debug === '1' ? '1' : undefined;
}
function getTraceFlags(carrier, getter) {
const traceFlags = getHeaderValue(carrier, getter, X_B3_SAMPLED);
const debug = getDebug(carrier, getter);
if (debug === '1' || VALID_SAMPLED_VALUES.has(traceFlags)) {
return TraceFlags.SAMPLED;
}
if (traceFlags === undefined || VALID_UNSAMPLED_VALUES.has(traceFlags)) {
return TraceFlags.NONE;
}
// This indicates to isValidSampledValue that this is not valid
return;
}
/**
* Propagator for the B3 multiple-header HTTP format.
* Based on: https://github.com/openzipkin/b3-propagation
*/
export class B3MultiPropagator {
inject(context, carrier, setter) {
const spanContext = trace.getSpanContext(context);
if (!spanContext ||
!isSpanContextValid(spanContext) ||
isTracingSuppressed(context))
return;
const debug = context.getValue(B3_DEBUG_FLAG_KEY);
setter.set(carrier, X_B3_TRACE_ID, spanContext.traceId);
setter.set(carrier, X_B3_SPAN_ID, spanContext.spanId);
// According to the B3 spec, if the debug flag is set,
// the sampled flag shouldn't be propagated as well.
if (debug === '1') {
setter.set(carrier, X_B3_FLAGS, debug);
}
else if (spanContext.traceFlags !== undefined) {
// We set the header only if there is an existing sampling decision.
// Otherwise we will omit it => Absent.
setter.set(carrier, X_B3_SAMPLED, (TraceFlags.SAMPLED & spanContext.traceFlags) === TraceFlags.SAMPLED
? '1'
: '0');
}
}
extract(context, carrier, getter) {
const traceId = getTraceId(carrier, getter);
const spanId = getSpanId(carrier, getter);
const traceFlags = getTraceFlags(carrier, getter);
const debug = getDebug(carrier, getter);
if (isValidTraceId(traceId) &&
isValidSpanId(spanId) &&
isValidSampledValue(traceFlags)) {
context = context.setValue(B3_DEBUG_FLAG_KEY, debug);
return trace.setSpanContext(context, {
traceId,
spanId,
isRemote: true,
traceFlags,
});
}
return context;
}
fields() {
return [
X_B3_TRACE_ID,
X_B3_SPAN_ID,
X_B3_FLAGS,
X_B3_SAMPLED,
X_B3_PARENT_SPAN_ID,
];
}
}
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