Add support for W3C traceparent header (#834)

src/Sentry/Laravel/Features/HttpClientIntegration.php

@@ -18,6 +18,7 @@
 use Sentry\Tracing\SpanStatus;
 use function Sentry\getBaggage;
 use function Sentry\getTraceparent;
+use function Sentry\getW3CTraceparent;
 
 class HttpClientIntegration extends Feature
 {
@@ -55,7 +56,8 @@ public function attachTracingHeadersToRequest(RequestInterface $request)
         if ($this->shouldAttachTracingHeaders($request)) {
             return $request
                 ->withHeader('baggage', getBaggage())
-                ->withHeader('sentry-trace', getTraceparent());
+                ->withHeader('sentry-trace', getTraceparent())
+                ->withHeader('traceparent', getW3CTraceparent());
         }
 
         return $request;

src/Sentry/Laravel/Integration.php

@@ -22,6 +22,7 @@
 use function Sentry\configureScope;
 use function Sentry\getBaggage;
 use function Sentry\getTraceparent;
+use function Sentry\getW3CTraceparent;
 
 class Integration implements IntegrationInterface
 {
@@ -168,7 +169,7 @@ static function ($carry, $key) use ($routeData) {
      */
     public static function sentryMeta(): string
     {
-        return self::sentryTracingMeta() . self::sentryBaggageMeta();
+        return self::sentryTracingMeta() . self::sentryW3CTracingMeta() . self::sentryBaggageMeta();
     }
 
     /**
@@ -181,6 +182,16 @@ public static function sentryTracingMeta(): string
         return sprintf('<meta name="sentry-trace" content="%s"/>', getTraceparent());
     }
 
+    /**
+     * Retrieve the `traceparent` meta tag with tracing information to link this request to front-end requests.
+     *
+     * @return string
+     */
+    public static function sentryW3CTracingMeta(): string
+    {
+        return sprintf('<meta name="traceparent" content="%s"/>', getW3CTraceparent());
+    }
+
     /**
      * Retrieve the `baggage` meta tag with information to link this request to front-end requests.
      * This propagates the Dynamic Sampling Context.

src/Sentry/Laravel/Tracing/Middleware.php

@@ -175,7 +175,7 @@ private function startTransaction(Request $request, HubInterface $sentry): void
         );
 
         $context = continueTrace(
-            $request->header('sentry-trace', ''),
+            $request->header('sentry-trace') ?? $request->header('traceparent', ''),
             $request->header('baggage', '')
         );