* sse: support client side "x-trace-id" header

Signed-off-by: neo <[email protected]>

Author: neowu

CHANGELOG.md

@@ -5,6 +5,7 @@
 * sse: send ErrorResponse to client via "event: error" on exception
 * sse: log clientIP on sse:close action
 * log-exporter: export action and event in parquet format
+* sse: support client side "x-trace-id" header
 
 ### 9.1.6 (2/10/2025 - 2/25/2025)
 

core-ng/src/main/java/core/framework/internal/web/sse/ServerSentEventCloseHandler.java

@@ -9,19 +9,20 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.List;
+import java.util.Map;
 
 class ServerSentEventCloseHandler<T> implements ExchangeCompletionListener {
     private static final Logger LOGGER = LoggerFactory.getLogger(ServerSentEventCloseHandler.class);
     final ServerSentEventContextImpl<T> context;
     private final LogManager logManager;
     private final ChannelImpl<T> channel;
-    private final String clientIP;
+    private final Map<String, String> logContext;
 
-    ServerSentEventCloseHandler(LogManager logManager, ChannelImpl<T> channel, ServerSentEventContextImpl<T> context, String clientIP) {
+    ServerSentEventCloseHandler(LogManager logManager, ChannelImpl<T> channel, ServerSentEventContextImpl<T> context, Map<String, String> logContext) {
         this.logManager = logManager;
         this.channel = channel;
         this.context = context;
-        this.clientIP = clientIP;
+        this.logContext = logContext;
     }
 
     @Override
@@ -36,7 +37,11 @@ public void exchangeEvent(HttpServerExchange exchange, NextListener next) {
                 List<String> refIds = List.of(channel.refId);
                 actionLog.refIds = refIds;
                 actionLog.correlationIds = refIds;
-                actionLog.context.put("client_ip", List.of(clientIP));
+
+                for (Map.Entry<String, String> entry : logContext.entrySet()) {
+                    actionLog.context(entry.getKey(), entry.getValue());
+                }
+
                 if (!channel.groups.isEmpty()) actionLog.context("group", channel.groups.toArray());
                 context.remove(channel);
                 channel.shutdown();

core-ng/src/main/java/core/framework/internal/web/sse/ServerSentEventHandler.java

@@ -27,12 +27,14 @@
 import java.nio.ByteBuffer;
 import java.time.Duration;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 public class ServerSentEventHandler implements HttpHandler {
     // persistent connection, use longer max process time
     // though LB backend timeout is to 600s, for long time sse, it should be processed via message queue
     static final long MAX_PROCESS_TIME_IN_NANO = Duration.ofSeconds(300).toNanos();
+    static final HttpString HEADER_TRACE_ID = new HttpString("x-trace-id");
 
     private static final HttpString LAST_EVENT_ID = new HttpString("Last-Event-ID");
     private final Logger logger = LoggerFactory.getLogger(ServerSentEventHandler.class);
@@ -97,9 +99,18 @@ void handle(HttpServerExchange exchange, StreamSinkChannel sink) {
 
             channel = new ChannelImpl<>(exchange, sink, support.context, support.builder, actionLog.id);
             actionLog.context("channel", channel.id);
+
+            Map<String, String> logContext = new HashMap<>();
+            logContext.put("client_id", request.clientIP());
+            String traceId = exchange.getRequestHeaders().getFirst(HEADER_TRACE_ID);    // used by frontend to trace request
+            if (traceId != null) {
+                actionLog.context.put("trace_id", List.of(traceId));
+                logContext.put("trace_id", traceId);
+            }
+
             sink.getWriteSetter().set(channel.writeListener);
             support.context.add(channel);
-            exchange.addExchangeCompleteListener(new ServerSentEventCloseHandler<>(logManager, channel, support.context, request.clientIP()));
+            exchange.addExchangeCompleteListener(new ServerSentEventCloseHandler<>(logManager, channel, support.context, logContext));
 
             channel.sendBytes(Strings.bytes("retry: 5000\n\n"));    // set browser retry to 5s