chore: set useElasticTraceparentHeader's default value to false

CHANGELOG4.asciidoc

@@ -39,6 +39,8 @@
 * Add a warning message when a duration config option is provided
   without units. ({issues}2121[#2121])
 
+* Change default value of `useElasticTraceparentHeader` config option to `false`.
+
 [[release-notes-3.x]]
 === Node.js Agent version 3.x
 

docs/configuration.asciidoc

@@ -1423,7 +1423,7 @@ The captured request body (if any) is stored on the `span.db.statement` field. C
 ==== `useElasticTraceparentHeader`
 
 * *Type:* Boolean
-* *Default:* `true`
+* *Default:* `false`
 * *Env:* `ELASTIC_APM_USE_ELASTIC_TRACEPARENT_HEADER`
 
 To enable {apm-guide-ref}/apm-distributed-tracing.html[distributed tracing], the agent

docs/upgrade-to-v4.asciidoc

@@ -34,6 +34,12 @@ Support for `filterHttpHeaders` config option has been removed. Redaction of
 HTTP headers and also request cookies is controlled by the existing config
 option <<sanitize-field-names, `sanitizeFieldNames`>>.
 
+===== `useElasticTraceparentHeader`
+
+The default value of `useElasticTraceparentHeader` config option has changed
+to `false` since the standard `traceparent` header is added in outgoing
+HTTP requests. If you want the agent to continue sending `elastic-apm-traceparent`
+HTTP header you can set to `true` via env var or start options.
 
 [[v4-api-changes]]
 ==== API changes

lib/config/schema.js

@@ -118,7 +118,7 @@ const DEFAULTS = {
   transactionIgnoreUrls: [],
   transactionMaxSpans: 500,
   transactionSampleRate: 1.0,
-  useElasticTraceparentHeader: true,
+  useElasticTraceparentHeader: false,
   usePathAsTransactionName: false,
   verifyServerCert: true,
 };

test/instrumentation/modules/http/outgoing.test.js

@@ -57,7 +57,7 @@ test(
 
 test(
   'http: consider useElasticTraceparentHeader config option',
-  echoTest('http', { useElasticTraceparentHeader: false }, (port, cb) => {
+  echoTest('http', { useElasticTraceparentHeader: true }, (port, cb) => {
     var options = { port };
     return http.request(options, cb);
   }),
@@ -364,13 +364,13 @@ function echoTest(type, opts, handler) {
 
       var traceparent = req.getHeader('traceparent');
       t.ok(traceparent, 'should have traceparent header');
-      if (opts && opts.useElasticTraceparentHeader === false) {
-        t.strictEqual(req.getHeader('elastic-apm-traceparent'), undefined);
-      } else {
+      if (opts && opts.useElasticTraceparentHeader) {
         t.ok(
           req.getHeader('elastic-apm-traceparent'),
           'should have elastic-apm-traceparent header',
         );
+      } else {
+        t.strictEqual(req.getHeader('elastic-apm-traceparent'), undefined);
       }
 
       var expected = TraceParent.fromString(trans._context.toString());

test/instrumentation/modules/http2.test.js

@@ -602,8 +602,6 @@ function assertPath(t, trans, secure, port, path, httpVersion) {
   if (trans.context.request.headers.traceparent) {
     expectedReqHeaders.traceparent = trans.context.request.headers.traceparent;
     expectedReqHeaders.tracestate = trans.context.request.headers.tracestate;
-    expectedReqHeaders['elastic-apm-traceparent'] =
-      trans.context.request.headers['elastic-apm-traceparent'];
   }
 
   // What is "expected" for transaction.context.request.socket.remote_address