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AWSXRayPropagator.ts
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AWSXRayPropagator.ts
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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* or in the "license" file accompanying this file. This file 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 {
Context,
HttpTextPropagator,
SpanContext,
TraceFlags,
SetterFunction,
GetterFunction,
INVALID_TRACE_ID,
INVALID_SPAN_ID,
} from '@opentelemetry/api';
import {
getParentSpanContext,
setExtractedSpanContext,
INVALID_SPAN_CONTEXT,
isValid,
} from '@opentelemetry/core';
export const AWSXRAY_TRACE_ID_HEADER = 'X-Amzn-Trace-Id';
const TRACE_HEADER_DELIMITER = ';';
const KV_DELIMITER = '=';
const TRACE_ID_KEY = 'Root';
const TRACE_ID_LENGTH = 35;
const TRACE_ID_VERSION = '1';
const TRACE_ID_DELIMITER = '-';
const TRACE_ID_DELIMITER_INDEX_1 = 1;
const TRACE_ID_DELIMITER_INDEX_2 = 10;
const TRACE_ID_FIRST_PART_LENGTH = 8;
const PARENT_ID_KEY = 'Parent';
const SAMPLED_FLAG_KEY = 'Sampled';
const SAMPLED_FLAG_LENGTH = 1;
const IS_SAMPLED = '1';
const NOT_SAMPLED = '0';
const VALID_TRACEID_REGEX = /^([0-9a-f]{32})$/i;
const VALID_SPANID_REGEX = /^[0-9a-f]{16}$/i;
/**
* Implementation of the AWS X-Ray Trace Header propagation protocol. See <a href=
* https://https://docs.aws.amazon.com/xray/latest/devguide/xray-concepts.html#xray-concepts-tracingheader>AWS
* Tracing header spec</a>
*
* An example AWS Xray Tracing Header is shown below:
* X-Amzn-Trace-Id: Root=1-5759e988-bd862e3fe1be46a994272793;Parent=53995c3f42cd8ad8;Sampled=1
*/
export class AWSXRayPropagator implements HttpTextPropagator {
inject(context: Context, carrier: unknown, setter: SetterFunction) {
const spanContext = getParentSpanContext(context);
if (!spanContext || !isValid(spanContext)) return;
const otTraceId = spanContext.traceId;
const xrayTraceId =
TRACE_ID_VERSION +
TRACE_ID_DELIMITER +
otTraceId.substring(0, TRACE_ID_FIRST_PART_LENGTH) +
TRACE_ID_DELIMITER +
otTraceId.substring(TRACE_ID_FIRST_PART_LENGTH);
const parentId = spanContext.spanId;
const samplingFlag = spanContext.traceFlags ? IS_SAMPLED : NOT_SAMPLED;
// TODO: Add OT trace state to the X-Ray trace header
const traceHeader =
TRACE_ID_KEY +
KV_DELIMITER +
xrayTraceId +
TRACE_HEADER_DELIMITER +
PARENT_ID_KEY +
KV_DELIMITER +
parentId +
TRACE_HEADER_DELIMITER +
SAMPLED_FLAG_KEY +
KV_DELIMITER +
samplingFlag;
setter(carrier, AWSXRAY_TRACE_ID_HEADER, traceHeader);
}
extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
const spanContext = this.getSpanContextFromHeader(carrier, getter);
if (!isValid(spanContext)) return context;
return setExtractedSpanContext(context, spanContext);
}
private getSpanContextFromHeader(
carrier: unknown,
getter: GetterFunction
): SpanContext {
const traceHeader = getter(carrier, AWSXRAY_TRACE_ID_HEADER)
? getter(carrier, AWSXRAY_TRACE_ID_HEADER)
: getter(carrier, AWSXRAY_TRACE_ID_HEADER.toLowerCase());
// Only if the returned traceHeader is no empty string can be extracted
if (!traceHeader || typeof traceHeader !== 'string')
return INVALID_SPAN_CONTEXT;
let pos = 0;
let trimmedPart: string;
let parsedTraceId = INVALID_TRACE_ID;
let parsedSpanId = INVALID_SPAN_ID;
let parsedTraceFlags = null;
while (pos < traceHeader.length) {
const delimiterIndex = traceHeader.indexOf(TRACE_HEADER_DELIMITER, pos);
if (delimiterIndex >= 0) {
trimmedPart = traceHeader.substring(pos, delimiterIndex).trim();
pos = delimiterIndex + 1;
} else {
//last part
trimmedPart = traceHeader.substring(pos).trim();
pos = traceHeader.length;
}
const equalsIndex = trimmedPart.indexOf(KV_DELIMITER);
const value = trimmedPart.substring(equalsIndex + 1);
if (trimmedPart.startsWith(TRACE_ID_KEY)) {
parsedTraceId = this._parseTraceId(value);
}
if (trimmedPart.startsWith(PARENT_ID_KEY)) {
parsedSpanId = this._parseSpanId(value);
}
if (trimmedPart.startsWith(SAMPLED_FLAG_KEY)) {
parsedTraceFlags = this._parseTraceFlag(value);
}
}
if (parsedTraceFlags === null) {
return INVALID_SPAN_CONTEXT;
}
const resultSpanContext: SpanContext = {
traceId: parsedTraceId,
spanId: parsedSpanId,
traceFlags: parsedTraceFlags,
isRemote: true,
};
if (!isValid(resultSpanContext)) {
return INVALID_SPAN_CONTEXT;
}
return resultSpanContext;
}
private _parseTraceId(xrayTraceId: string): string {
// Check length of trace id
if (xrayTraceId.length !== TRACE_ID_LENGTH) {
return INVALID_TRACE_ID;
}
// Check version trace id version
if (!xrayTraceId.startsWith(TRACE_ID_VERSION)) {
return INVALID_TRACE_ID;
}
// Check delimiters
if (
xrayTraceId.charAt(TRACE_ID_DELIMITER_INDEX_1) !== TRACE_ID_DELIMITER ||
xrayTraceId.charAt(TRACE_ID_DELIMITER_INDEX_2) !== TRACE_ID_DELIMITER
) {
return INVALID_TRACE_ID;
}
const epochPart = xrayTraceId.substring(
TRACE_ID_DELIMITER_INDEX_1 + 1,
TRACE_ID_DELIMITER_INDEX_2
);
const uniquePart = xrayTraceId.substring(
TRACE_ID_DELIMITER_INDEX_2 + 1,
TRACE_ID_LENGTH
);
const resTraceId = epochPart + uniquePart;
// Check the content of trace id
if (!VALID_TRACEID_REGEX.test(resTraceId)) {
return INVALID_TRACE_ID;
}
return resTraceId;
}
private _parseSpanId(xrayParentId: string): string {
return VALID_SPANID_REGEX.test(xrayParentId)
? xrayParentId
: INVALID_SPAN_ID;
}
private _parseTraceFlag(xraySampledFlag: string): TraceFlags | null {
if (
xraySampledFlag.length === SAMPLED_FLAG_LENGTH &&
xraySampledFlag === NOT_SAMPLED
) {
return TraceFlags.NONE;
}
if (xraySampledFlag === IS_SAMPLED) {
return TraceFlags.SAMPLED;
}
return null;
}
}