Fix elastic#1770 support for proxies in destination context (elastic#…

…2126)

* Fix elastic#1770 support for proxies in destination context

Fix for elastic#1770, ensures only a single url is set

CHANGELOG.asciidoc

@@ -51,6 +51,8 @@ Notes:
 * Fixed error where SQS messages sent without an active transactions could
   crash the agent. ({issues}2113[#2113])
 
+* Fixed support for proxies in destination context ({issues}1770[#1770])
+
 [[release-notes-x.x.x]]
 ==== 3.16.0 - 2021/06/14
 

lib/instrumentation/http-shared.js

@@ -285,6 +285,9 @@ function getUrlFromRequestAndOptions (req, options, fallbackProtocol) {
   options = options || {}
   req = req || {}
   req.agent = req.agent || {}
+  if (isProxiedRequest(req)) {
+    return req.path
+  }
 
   const port = options.port ? `:${options.port}` : ''
   // req.host and req.protocol are node versions v14.5.0/v12.19.0 and later
@@ -294,4 +297,8 @@ function getUrlFromRequestAndOptions (req, options, fallbackProtocol) {
   return `${protocol}//${host}${port}${req.path}`
 }
 
+function isProxiedRequest (req) {
+  return req.path.indexOf('https:') === 0 || req.path.indexOf('http:') === 0
+}
+
 exports.getUrlFromRequestAndOptions = getUrlFromRequestAndOptions

test/instrumentation/github-issue-1770.js

@@ -0,0 +1,45 @@
+const agent = require('../..').start({
+  serviceName: 'test',
+  secretToken: 'test',
+  centralConfig: false,
+  metricsInterval: 0
+})
+
+const tape = require('tape')
+const http = require('http')
+const mockClient = require('../_mock_http_client')
+
+function resetAgent (cb) {
+  agent._transport = mockClient(3, cb)
+}
+
+tape.test('span url contains single url', function (t) {
+  resetAgent(function (results) {
+    t.equals(results.spans.length, 1, 'one span')
+
+    const span = results.spans.pop()
+    const url = span.context.http.url
+
+    // ensure url is not in the form
+    // http://127.0.0.1:59281http://127.0.0.1/foo
+    t.equals(url, 'http://127.0.0.1/foo', 'records single url only')
+    t.end()
+  })
+  const server = http.createServer(function (req, res) {
+    res.end('hello')
+  })
+  server.unref()
+  server.listen(0, '0.0.0.0', () => {
+    const port = server.address().port
+    agent.startTransaction()
+    const opts = {
+      host: '127.0.0.1',
+      port,
+      method: 'GET',
+      path: 'http://127.0.0.1/foo'
+    }
+    const client = http.request(opts)
+    client.end()
+    agent.endTransaction()
+  })
+})