80 lines
2.5 KiB
JavaScript
80 lines
2.5 KiB
JavaScript
'use strict';
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const opentelemetryApi = require('@opentelemetry/api');
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const asyncHandler = require('../lib/express-async-handler');
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const { captureSpanProcessor } = require('./tracing');
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const serializeSpan = require('./serialize-span');
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// From the current active context, grab the `traceId`. The `traceId` will be
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// shared for the whole request because all spans live under the root span.
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function getActiveTraceId() {
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//const rootCtx = opentelemetryApi.ROOT_CONTEXT;
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const activeCtx = opentelemetryApi.context.active();
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if (activeCtx) {
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const span = opentelemetryApi.trace.getSpan(activeCtx);
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if (span) {
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const traceId = span.spanContext().traceId;
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return traceId;
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}
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}
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}
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// Handles keeping track of tracing spans for each request.
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// Also adds the traceId to the to the `X-Trace-Id` response header.
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async function handleTracingMiddleware(req, res, next) {
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const traceId = getActiveTraceId();
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if (traceId) {
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// Add the OpenTelemetry trace ID to the `X-Trace-Id` response header so
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// we can cross-reference. We can use this to lookup the request in
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// Jaeger.
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res.set('X-Trace-Id', traceId);
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// Start keeping track of all of spans that happen during the request
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captureSpanProcessor.trackSpansInTrace(traceId);
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// Cleanup after the request is done
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res.on('finish', function () {
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captureSpanProcessor.dropSpansInTrace(traceId);
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});
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}
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next();
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}
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// Get all of spans we're willing to show to the user.
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//
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// We only care about showing the external API HTTP requests to the user so they
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// can tell what part of the Matrix API is being so slow.
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function getSerializableSpans() {
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const traceId = getActiveTraceId();
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if (traceId) {
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const spans = captureSpanProcessor.getSpansInTrace(traceId) ?? [];
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// We only care about showing the external API HTTP requests to the user
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const filteredSpans = spans.filter((span) => {
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return [
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// `http`/`https` requests
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'@opentelemetry/instrumentation-http',
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// Native `fetch`
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'opentelemetry-instrumentation-node-18-fetch',
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// This will get `tcp.connect` calls which `fetch` does but not the full request lifecycle
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//'@opentelemetry/instrumentation-net',
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].includes(span.instrumentationLibrary.name);
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});
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const serializableSpans = filteredSpans.map((span) => serializeSpan(span));
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return serializableSpans;
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}
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return [];
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}
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module.exports = {
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handleTracingMiddleware: asyncHandler(handleTracingMiddleware),
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getSerializableSpans,
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getActiveTraceId,
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};
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