feat: support W3C TraceContext traceparent header (#1587)

* feat: support W3C TraceContext traceparent header

* test: add tests for useElasticTraceparentHeader config

lib/config.js

@@ -72,6 +72,7 @@ var DEFAULTS = {
   stackTraceLimit: 50,
   transactionMaxSpans: 500,
   transactionSampleRate: 1.0,
+  useElasticTraceparentHeader: true,
   usePathAsTransactionName: false,
   verifyServerCert: true
 }
@@ -125,6 +126,7 @@ var ENV_TABLE = {
   stackTraceLimit: 'ELASTIC_APM_STACK_TRACE_LIMIT',
   transactionMaxSpans: 'ELASTIC_APM_TRANSACTION_MAX_SPANS',
   transactionSampleRate: 'ELASTIC_APM_TRANSACTION_SAMPLE_RATE',
+  useElasticTraceparentHeader: 'ELASTIC_APM_USE_ELASTIC_TRACEPARENT_HEADER',
   usePathAsTransactionName: 'ELASTIC_APM_USE_PATH_AS_TRANSACTION_NAME',
   verifyServerCert: 'ELASTIC_APM_VERIFY_SERVER_CERT'
 }

lib/instrumentation/http-shared.js

@@ -22,7 +22,7 @@ exports.instrumentRequest = function (agent, moduleName) {
           // don't leak previous transaction
           agent._instrumentation.currentTransaction = null
         } else {
-          var traceparent = req.headers['elastic-apm-traceparent']
+          var traceparent = req.headers['elastic-apm-traceparent'] || req.headers.traceparent
           var trans = agent.startTransaction(null, null, {
             childOf: traceparent
           })
@@ -150,7 +150,11 @@ exports.traceOutgoingRequest = function (agent, moduleName, method) {
       // Use the transaction context as the parent, in this case.
       var parent = span || agent.currentTransaction
       if (parent && parent._context && shouldPropagateTraceContext(options)) {
-        options.headers['elastic-apm-traceparent'] = parent._context.toString()
+        const headerValue = parent._context.toString()
+        options.headers.traceparent = headerValue
+        if (agent._conf.useElasticTraceparentHeader) {
+          options.headers['elastic-apm-traceparent'] = headerValue
+        }
       }
 
       var req = orig.apply(this, newArgs)

lib/lambda.js

@@ -76,9 +76,16 @@ module.exports = function elasticApmAwsLambda (agent) {
       let parentId
       if (payload.headers !== undefined) {
         for (const [key, value] of Object.entries(payload.headers)) {
-          if (key.toLowerCase() === 'elastic-apm-traceparent') {
+          const lowerCaseKey = key.toLowerCase()
+          if (lowerCaseKey === 'elastic-apm-traceparent') {
             parentId = value
             break
+          } else if (lowerCaseKey === 'traceparent') {
+            /**
+             * We do not break here because we want to make sure to use
+             * elastic-apm-traceparent if available.
+             */
+            parentId = value
           }
         }
       }

test/instrumentation/_agent.js

@@ -13,12 +13,16 @@ var sharedInstrumentation
 
 module.exports = function mockAgent (expected, cb) {
   var agent = {
-    _conf: config({
-      abortedErrorThreshold: '250ms',
-      centralConfig: false,
-      errorOnAbortedRequests: false,
-      metricsInterval: 0
-    }),
+    _config: function (opts) {
+      this._conf = config(
+        Object.assign({
+          abortedErrorThreshold: '250ms',
+          centralConfig: false,
+          errorOnAbortedRequests: false,
+          metricsInterval: 0
+        }, opts)
+      )
+    },
     _errorFilters: new Filters(),
     _transactionFilters: new Filters(),
     _spanFilters: new Filters(),
@@ -28,6 +32,7 @@ module.exports = function mockAgent (expected, cb) {
     }),
     setFramework: function () {}
   }
+  agent._config()
 
   agent._metrics = new Metrics(agent)
   agent._metrics.start()

test/instrumentation/modules/http/aws.js

@@ -19,6 +19,7 @@ AWS.config.update({
 test('non aws-sdk request', function (t) {
   const server = http.createServer(function (req, res) {
     t.equal(req.headers.authorization, undefined, 'no authorization header')
+    t.ok(req.headers.traceparent.length > 0, 'traceparent header')
     t.ok(req.headers['elastic-apm-traceparent'].length > 0, 'elastic-apm-traceparent header')
     res.end()
     server.close()
@@ -40,6 +41,7 @@ test('non aws-sdk request', function (t) {
 test('aws-sdk request', function (t) {
   const server = http.createServer(function (req, res) {
     t.equal(req.headers.authorization.substr(0, 5), 'AWS4-', 'AWS authorization header')
+    t.equal(req.headers.traceparent, undefined, 'no traceparent header')
     t.equal(req.headers['elastic-apm-traceparent'], undefined, 'no elastic-apm-traceparent header')
     res.end()
     server.close()

test/instrumentation/modules/http/basic.js

@@ -82,23 +82,41 @@ test('new http.Server', function (t) {
     server.on('request', onRequest(t))
     sendRequest(server)
   })
+
+  t.test('support elastic-apm-traceparent header', function (t) {
+    resetAgent(function (data) {
+      assert(t, data)
+      server.close()
+      t.end()
+    })
+
+    var server = new http.Server()
+    server.on('request', onRequest(t, true))
+    sendRequest(server, undefined, true)
+  })
 })
 
-function sendRequest (server, timeout) {
+function sendRequest (server, timeout, useElasticHeader) {
   server.listen(function () {
     var port = server.address().port
     var context = TraceParent.startOrResume(null, {
       transactionSampleRate: 1.0
     })
 
+    const headers = {}
+    const contextValue = context.toString()
+    if (useElasticHeader) {
+      headers['elastic-apm-traceparent'] = contextValue
+    } else {
+      headers.traceparent = contextValue
+    }
+
     var req = http.request({
       hostname: 'localhost',
       port: port,
       path: '/',
       method: 'GET',
-      headers: {
-        'elastic-apm-traceparent': context.toString()
-      }
+      headers: headers
     }, function (res) {
       if (timeout) throw new Error('should not get to here')
       res.resume()
@@ -113,9 +131,9 @@ function sendRequest (server, timeout) {
   })
 }
 
-function onRequest (t) {
+function onRequest (t, useElasticHeader) {
   return function onRequestHandler (req, res) {
-    var traceparent = req.headers['elastic-apm-traceparent']
+    var traceparent = useElasticHeader ? req.headers['elastic-apm-traceparent'] : req.headers.traceparent
     var parent = TraceParent.fromString(traceparent)
     var context = agent.currentTransaction._context
     t.equal(parent.traceId, context.traceId, 'context trace id matches parent trace id')

test/instrumentation/modules/http/outgoing.js

@@ -30,6 +30,11 @@ test('http.request(options, callback)', echoTest('http', (port, cb) => {
   return http.request(options, cb)
 }))
 
+test('http: consider useElasticTraceparentHeader config option', echoTest('http', { useElasticTraceparentHeader: false }, (port, cb) => {
+  var options = { port }
+  return http.request(options, cb)
+}))
+
 methods.forEach(function (name) {
   test(`http.${name}(urlString)`, echoTest('http', (port, cb) => {
     var urlString = `http://localhost:${port}`
@@ -75,6 +80,11 @@ test('https.request(options, callback)', echoTest('https', (port, cb) => {
   return https.request(options, cb)
 }))
 
+test('https: consider useElasticTraceparentHeader config option', echoTest('https', { useElasticTraceparentHeader: false }, (port, cb) => {
+  var options = { port, rejectUnauthorized: false }
+  return https.request(options, cb)
+}))
+
 methods.forEach(function (name) {
   test(`https.${name}(urlString, options)`, echoTest('https', (port, cb) => {
     var urlString = `https://localhost:${port}`
@@ -111,10 +121,15 @@ methods.forEach(function (name) {
   }
 })
 
-function echoTest (type, handler) {
+function echoTest (type, opts, handler) {
+  if (arguments.length === 2) {
+    handler = opts
+    opts = undefined
+  }
+
   return function (t) {
     echoServer(type, (cp, port) => {
-      resetAgent(data => {
+      resetAgent(opts, data => {
         t.equal(data.transactions.length, 1, 'has one transaction')
         t.equal(data.spans.length, 1, 'has one span')
         t.equal(data.spans[0].name, 'GET localhost:' + port + '/', 'has expected span name')
@@ -135,8 +150,13 @@ function echoTest (type, handler) {
         res.resume()
       })
 
-      var traceparent = req.getHeader('elastic-apm-traceparent')
-      t.ok(traceparent, 'should have elastic-apm-traceparent header')
+      var traceparent = req.getHeader('traceparent')
+      t.ok(traceparent, 'should have traceparent header')
+      if (opts && opts.useElasticTraceparentHeader === false) {
+        t.equal(req.getHeader('elastic-apm-traceparent'), undefined)
+      } else {
+        t.ok(req.getHeader('elastic-apm-traceparent'), 'should have elastic-apm-traceparent header')
+      }
 
       var expected = TraceParent.fromString(trans._context.toString())
       var received = TraceParent.fromString(traceparent)
@@ -153,7 +173,8 @@ function echoTest (type, handler) {
   }
 }
 
-function resetAgent (cb) {
+function resetAgent (opts, cb) {
   agent._instrumentation.currentTransaction = null
+  agent._config(opts)
   agent._transport = mockClient(2, cb)
 }

test/lambda/promises.js

@@ -53,7 +53,7 @@ test('resolve with parent id header present', function (t) {
   const input = {
     name: 'world',
     headers: {
-      'Elastic-Apm-Traceparent': 'test'
+      traceparent: 'test'
     }
   }
   const output = 'Hello, world!'
@@ -84,7 +84,7 @@ test('resolve with parent id header present', function (t) {
       t.equal(agent.transactions.length, 1)
       assertTransaction(t, agent.transactions[0], name, context, input, output)
 
-      t.equal(input.headers['Elastic-Apm-Traceparent'], agent.transactions[0].opts.childOf, 'context trace id matches parent trace id')
+      t.equal(input.headers.traceparent, agent.transactions[0].opts.childOf, 'context trace id matches parent trace id')
 
       t.end()
     }