Add ServerTiming response propagator (#213)

* Add ServerTiming response propagator
* Add ServerTimingPropagator
* Amend Symfony tests to include server-timing tests
* Amend composer.json
* Reference correct class
* Add package to .gitsplit.yml
* Add ServerTiming to tested packages

Author: cedricziel

composer.json

@@ -16,7 +16,8 @@
     "symfony/http-client-contracts": "*"
   },
   "suggest": {
-    "open-telemetry/opentelemetry-propagation-traceresponse": "Automatically propagate the context to the client."
+    "open-telemetry/opentelemetry-propagation-server-timing": "Automatically propagate the context to the client through server-timing headers.",
+    "open-telemetry/opentelemetry-propagation-traceresponse": "Automatically propagate the context to the client through trace-response headers."
   },
   "require-dev": {
     "friendsofphp/php-cs-fixer": "^3",
@@ -29,7 +30,8 @@
     "phpunit/phpunit": "^9.5",
     "vimeo/psalm": "^4.0",
     "symfony/http-client": "^5.4||^6.0",
-    "open-telemetry/opentelemetry-propagation-traceresponse": "*"
+    "open-telemetry/opentelemetry-propagation-traceresponse": "*",
+    "open-telemetry/opentelemetry-propagation-server-timing": "*"
   },
   "autoload": {
     "psr-4": {

src/SymfonyInstrumentation.php

@@ -120,6 +120,12 @@ public static function register(): void
 
                 $span->setAttribute(TraceAttributes::HTTP_RESPONSE_BODY_SIZE, $contentLength);
 
+                // Propagate server-timing header to response, if ServerTimingPropagator is present
+                if (class_exists('OpenTelemetry\Contrib\Propagation\ServerTiming\ServerTimingPropagator')) {
+                    $prop = new \OpenTelemetry\Contrib\Propagation\ServerTiming\ServerTimingPropagator();
+                    $prop->inject($response, ResponsePropagationSetter::instance(), $scope->context());
+                }
+
                 // Propagate traceresponse header to response, if TraceResponsePropagator is present
                 if (class_exists('OpenTelemetry\Contrib\Propagation\TraceResponse\TraceResponsePropagator')) {
                     $prop = new \OpenTelemetry\Contrib\Propagation\TraceResponse\TraceResponsePropagator();

tests/Integration/SymfonyInstrumentationTest.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\Tests\Instrumentation\Symfony\tests\Integration;
 
+use OpenTelemetry\Contrib\Propagation\ServerTiming\ServerTimingPropagator;
 use OpenTelemetry\Contrib\Propagation\TraceResponse\TraceResponsePropagator;
 use OpenTelemetry\SemConv\TraceAttributes;
 use Symfony\Component\EventDispatcher\EventDispatcher;
@@ -62,6 +63,12 @@ public function test_http_kernel_handle_attributes(): void
             $response->headers->all(),
             'traceresponse header is present if TraceResponsePropagator is present'
         );
+
+        $this->assertArrayHasKey(
+            ServerTimingPropagator::SERVER_TIMING,
+            $response->headers->all(),
+            'server-timings header is present if ServerTimingPropagator is present'
+        );
     }
 
     public function test_http_kernel_handle_stream_response(): void
@@ -81,6 +88,12 @@ public function test_http_kernel_handle_stream_response(): void
             $response->headers->all(),
             'traceresponse header is present if TraceResponsePropagator is present'
         );
+
+        $this->assertArrayHasKey(
+            ServerTimingPropagator::SERVER_TIMING,
+            $response->headers->all(),
+            'server-timings header is present if ServerTimingPropagator is present'
+        );
     }
 
     public function test_http_kernel_handle_binary_file_response(): void
@@ -97,6 +110,12 @@ public function test_http_kernel_handle_binary_file_response(): void
             $response->headers->all(),
             'traceresponse header is present if TraceResponsePropagator is present'
         );
+
+        $this->assertArrayHasKey(
+            ServerTimingPropagator::SERVER_TIMING,
+            $response->headers->all(),
+            'server-timings header is present if ServerTimingPropagator is present'
+        );
     }
 
     public function test_http_kernel_handle_with_empty_route(): void
@@ -115,6 +134,12 @@ public function test_http_kernel_handle_with_empty_route(): void
             $response->headers->all(),
             'traceresponse header is present if TraceResponsePropagator is present'
         );
+
+        $this->assertArrayHasKey(
+            ServerTimingPropagator::SERVER_TIMING,
+            $response->headers->all(),
+            'server-timings header is present if ServerTimingPropagator is present'
+        );
     }
 
     public function test_http_kernel_handle_without_route(): void
@@ -131,6 +156,12 @@ public function test_http_kernel_handle_without_route(): void
             $response->headers->all(),
             'traceresponse header is present if TraceResponsePropagator is present'
         );
+
+        $this->assertArrayHasKey(
+            ServerTimingPropagator::SERVER_TIMING,
+            $response->headers->all(),
+            'server-timings header is present if ServerTimingPropagator is present'
+        );
     }
 
     private function getHttpKernel(EventDispatcherInterface $eventDispatcher, $controller = null, RequestStack $requestStack = null, array $arguments = []): HttpKernel