Copy trace.id in threadcontext stash (elastic#83218)

because of incorrect change in elastic#81381 trace.id value (set in RestController basted on
traceparent) was not copied when stashing a context.
This commit do not allow to copy traceparent but allows to copy trace.id when stashing
ThreadContext

docs/changelog/83218.yaml

@@ -0,0 +1,5 @@
+pr: 83218
+summary: Copy `trace.id` in threadcontext stash
+area: Infra/Core
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/node/Node.java

@@ -728,7 +728,7 @@ protected Node(
             final Transport transport = networkModule.getTransportSupplier().get();
             Set<String> taskHeaders = Stream.concat(
                 pluginsService.filterPlugins(ActionPlugin.class).stream().flatMap(p -> p.getTaskHeaders().stream()),
-                Stream.of(Task.X_OPAQUE_ID_HTTP_HEADER, Task.TRACE_ID, Task.X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER)
+                Task.HEADERS_TO_COPY.stream()
             ).collect(Collectors.toSet());
             final TransportService transportService = newTransportService(
                 settings,

server/src/main/java/org/elasticsearch/tasks/Task.java

@@ -41,17 +41,14 @@ public class Task {
      */
     public static final String X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER = "X-elastic-product-origin";
 
-    public static final Set<String> HEADERS_TO_COPY = Set.of(
-        X_OPAQUE_ID_HTTP_HEADER,
-        TRACE_PARENT_HTTP_HEADER,
-        X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER
-    );
     /**
      * Parsed part of traceparent. It is stored in thread context and emitted in logs.
      * Has to be declared as a header copied over for tasks.
      */
     public static final String TRACE_ID = "trace.id";
 
+    public static final Set<String> HEADERS_TO_COPY = Set.of(X_OPAQUE_ID_HTTP_HEADER, TRACE_ID, X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER);
+
     private final long id;
 
     private final String type;

server/src/main/java/org/elasticsearch/tasks/TaskManager.java

@@ -730,4 +730,8 @@ public void cancelTaskAndDescendants(CancellableTask task, String reason, boolea
             throw new IllegalStateException("TaskCancellationService is not initialized");
         }
     }
+
+    public List<String> getTaskHeaders() {
+        return taskHeaders;
+    }
 }

server/src/test/java/org/elasticsearch/common/util/concurrent/ThreadContextTests.java

@@ -10,6 +10,7 @@
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.logging.HeaderWarning;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.tasks.Task;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -690,6 +691,26 @@ public void testPutHeaders() {
         assertEquals("value for key [foo] already present", e.getMessage());
     }
 
+    public void testHeadersCopiedOnStash() {
+        ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
+
+        try (ThreadContext.StoredContext ignored = threadContext.stashContext()) {
+            threadContext.putHeader(Task.X_OPAQUE_ID_HTTP_HEADER, "x-opaque-id");
+            threadContext.putHeader(Task.TRACE_ID, "0af7651916cd43dd8448eb211c80319c");
+            threadContext.putHeader(Task.X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER, "kibana");
+
+            try (ThreadContext.StoredContext ignored2 = threadContext.stashContext()) {
+                assertEquals("x-opaque-id", threadContext.getHeader(Task.X_OPAQUE_ID_HTTP_HEADER));
+                assertEquals("0af7651916cd43dd8448eb211c80319c", threadContext.getHeader(Task.TRACE_ID));
+                assertEquals("kibana", threadContext.getHeader(Task.X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER));
+            }
+
+            assertEquals("x-opaque-id", threadContext.getHeader(Task.X_OPAQUE_ID_HTTP_HEADER));
+            assertEquals("0af7651916cd43dd8448eb211c80319c", threadContext.getHeader(Task.TRACE_ID));
+            assertEquals("kibana", threadContext.getHeader(Task.X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER));
+        }
+    }
+
     /**
      * Sometimes wraps a Runnable in an AbstractRunnable.
      */

server/src/test/java/org/elasticsearch/node/NodeTests.java

@@ -31,11 +31,13 @@
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.plugins.RecoveryPlannerPlugin;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.tasks.Task;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.InternalTestCluster;
 import org.elasticsearch.test.MockHttpTransport;
 import org.elasticsearch.test.rest.FakeRestRequest;
 import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.transport.TransportService;
 import org.elasticsearch.xcontent.ContextParser;
 import org.elasticsearch.xcontent.MediaType;
 import org.elasticsearch.xcontent.NamedObjectNotFoundException;
@@ -60,6 +62,7 @@
 import static org.elasticsearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_SHARDS;
 import static org.elasticsearch.test.NodeRoles.dataNode;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
+import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
@@ -347,6 +350,15 @@ public void testNodeFailsToStartWhenThereAreMultipleRecoveryPlannerPluginsLoaded
         assertThat(exception.getMessage(), containsString("A single RecoveryPlannerPlugin was expected but got:"));
     }
 
+    public void testHeadersToCopyInTaskManagerAreTheSameAsDeclaredInTask() throws IOException {
+        Settings.Builder settings = baseSettings();
+        try (Node node = new MockNode(settings.build(), basePlugins())) {
+            final TransportService transportService = node.injector().getInstance(TransportService.class);
+            final List<String> taskHeaders = transportService.getTaskManager().getTaskHeaders();
+            assertThat(taskHeaders, containsInAnyOrder(Task.HEADERS_TO_COPY.toArray(new String[] {})));
+        }
+    }
+
     public static class MockRecoveryPlannerPlugin extends Plugin implements RecoveryPlannerPlugin {
         public MockRecoveryPlannerPlugin() {}