DataDog · rachelyangdog · Jul 23, 2025 · Jul 14, 2025 · Jul 14, 2025 · Jul 14, 2025
diff --git a/.../src/main/java/datadog/trace/bootstrap/instrumentation/decorator/HttpServerDecorator.java b/.../src/main/java/datadog/trace/bootstrap/instrumentation/decorator/HttpServerDecorator.java
@@ -26,6 +26,7 @@
 import datadog.trace.bootstrap.instrumentation.api.AgentSpan;
 import datadog.trace.bootstrap.instrumentation.api.AgentSpanContext;
 import datadog.trace.bootstrap.instrumentation.api.AgentTracer;
+import datadog.trace.bootstrap.instrumentation.api.Baggage;
 import datadog.trace.bootstrap.instrumentation.api.ErrorPriorities;
 import datadog.trace.bootstrap.instrumentation.api.InternalSpanTypes;
 import datadog.trace.bootstrap.instrumentation.api.ResourceNamePriorities;
@@ -37,6 +38,7 @@
 import datadog.trace.bootstrap.instrumentation.decorator.http.ClientIpAddressResolver;
 import java.net.InetAddress;
 import java.util.BitSet;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ExecutionException;
@@ -149,7 +151,17 @@ public AgentSpan startSpan(REQUEST_CARRIER carrier, Context context) {
 
   public AgentSpanContext.Extracted getExtractedSpanContext(Context context) {
     AgentSpan extractedSpan = AgentSpan.fromContext(context);
-    return extractedSpan == null ? null : (AgentSpanContext.Extracted) extractedSpan.context();
+    AgentSpanContext.Extracted extractedContext = null;
+    if (extractedSpan != null) {
+      extractedContext = (AgentSpanContext.Extracted) extractedSpan.context();
+      if (extractedContext instanceof TagContext) {
+        Baggage baggage = Baggage.fromContext(context);
+        if (baggage != null) {
+          setBaggageTags((TagContext) extractedContext, baggage.asMap());
+        }
+      }
+    }
+    return extractedContext;
   }
 
   public AgentSpan onRequest(
@@ -644,4 +656,24 @@ public boolean accept(String key, String value) {
       return true;
     }
   }
+
+  static void setBaggageTags(TagContext tagContext, Map<String, String> baggage) {
+    List<String> baggageTagKeys = Config.get().getTraceBaggageTagKeys();
+    if (baggageTagKeys.isEmpty()) {
+      return;
+    }
+    for (String key : baggageTagKeys) {
+      if ("*".equals(key)) {
+        // If the key is "*", we add all baggage items
+        for (Map.Entry<String, String> entry : baggage.entrySet()) {
+          tagContext.putTagIfAbsent("baggage." + entry.getKey(), entry.getValue());
+        }
+        break;
+      }
+      String value = baggage.get(key);
+      if (value != null) {
+        tagContext.putTagIfAbsent("baggage." + key, value);
+      }
+    }
+  }
 }
diff --git a/...t/groovy/datadog/trace/bootstrap/instrumentation/decorator/HttpServerDecoratorTest.groovy b/...t/groovy/datadog/trace/bootstrap/instrumentation/decorator/HttpServerDecoratorTest.groovy
@@ -17,6 +17,7 @@ import datadog.trace.bootstrap.instrumentation.api.AgentTracer.TracerAPI
 import datadog.trace.bootstrap.instrumentation.api.ContextVisitors
 import datadog.trace.bootstrap.instrumentation.api.ErrorPriorities
 import datadog.trace.bootstrap.instrumentation.api.ResourceNamePriorities
+import datadog.trace.bootstrap.instrumentation.api.TagContext
 import datadog.trace.bootstrap.instrumentation.api.Tags
 import datadog.trace.bootstrap.instrumentation.api.URIDataAdapter
 import datadog.trace.bootstrap.instrumentation.api.URIDefaultDataAdapter
@@ -29,6 +30,7 @@ import static datadog.trace.api.config.TraceInstrumentationConfig.HTTP_SERVER_DE
 import static datadog.trace.api.config.TraceInstrumentationConfig.HTTP_SERVER_RAW_QUERY_STRING
 import static datadog.trace.api.config.TraceInstrumentationConfig.HTTP_SERVER_RAW_RESOURCE
 import static datadog.trace.api.config.TraceInstrumentationConfig.HTTP_SERVER_TAG_QUERY_STRING
+import static datadog.trace.api.config.TracerConfig.TRACE_BAGGAGE_TAG_KEYS
 import static datadog.trace.api.gateway.Events.EVENTS
 
 class HttpServerDecoratorTest extends ServerDecoratorTest {
@@ -566,4 +568,54 @@ class HttpServerDecoratorTest extends ServerDecoratorTest {
       return reqHeaderDoneCount
     }
   }
+
+  def "test setBaggageTags default"() {
+    setup:
+    def tags = [:]
+
+    when:
+    def tagContext = new TagContext()
+    HttpServerDecorator.setBaggageTags(tagContext, ["user.id": "doggo", "account.id": "test", "session.id": "1234", "region": "us -east - 1"])
+    tagContext.tags.fillMap(tags)
+
+    then:
+    tags == ["baggage.user.id": "doggo", "baggage.account.id": "test", "baggage.session.id": "1234"]
+  }
+
+  def "test setBaggageTags does not overwrite"() {
+    setup:
+    def tags = [:]
+
+    when:
+    def tagContext = new TagContext()
+    tagContext.putTag("baggage.account.id", "staging")
+    HttpServerDecorator.setBaggageTags(tagContext, ["user.id": "doggo", "account.id": "test", "session.id": "1234", "region": "us -east - 1"])
+    tagContext.tags.fillMap(tags)
+
+    then:
+    tags == ["baggage.user.id": "doggo", "baggage.account.id": "staging", "baggage.session.id": "1234"]
+  }
+
+  def "test setBaggageTags with different configurations"() {
+    setup:
+    injectSysConfig(TRACE_BAGGAGE_TAG_KEYS, baggageTagKeysConfig)
+    def tags = [:]
+
+    when:
+    def tagContext = new TagContext()
+    HttpServerDecorator.setBaggageTags(tagContext, ["user.id": "doggo", "foo": "bar", "language": "en"])
+    tagContext.tags.fillMap(tags)
+
+    then:
+    tags == expectedTags
+
+    where:
+    baggageTagKeysConfig | expectedTags
+    "*"                  | ["baggage.user.id": "doggo", "baggage.foo": "bar", "baggage.language": "en"]
+    " "                  | [:]
+    "system.id"          | [:]
+    "user.id"            | ["baggage.user.id": "doggo"]
+    "foo"                | ["baggage.foo": "bar"]
+    "user.id,foo"        | ["baggage.user.id": "doggo", "baggage.foo": "bar"]
+  }
 }
@@ -785,6 +785,53 @@ abstract class HttpServerTest<SERVER> extends WithHttpServer<SERVER> {
     'GET'  | null | 'x-datadog-test-request-header' | 'bar' | ['request_header_tag': 'bar']
   }
 
+  def "test baggage span tags are properly added"() {
+    setup:
+    // Use default configuration for TRACE_BAGGAGE_TAG_KEYS (user.id, session.id, account.id)
+    def baggageHeader = "user.id=test-user,session.id=test-session,account.id=test-account,language=en"
+    def request = request(SUCCESS, 'GET', null)
+    .header("baggage", baggageHeader)
+    .build()
+    def response = client.newCall(request).execute()
+    if (isDataStreamsEnabled()) {
+      TEST_DATA_STREAMS_WRITER.waitForGroups(1)
+    }
+
+    expect:
+    response.code() == SUCCESS.status
+    response.body().string() == SUCCESS.body
+
+    and:
+    assertTraces(1) {
+      trace(spanCount(SUCCESS)) {
+        sortSpansByStart()
+        // Verify baggage tags are added for default configured keys only
+        serverSpan(it, null, null, 'GET', SUCCESS, [
+          "baggage.user.id": "test-user",
+          "baggage.session.id": "test-session",
+          "baggage.account.id": "test-account"
+          // "baggage.language" should NOT be present since it's not in default config
+        ])
+        if (hasHandlerSpan()) {
+          handlerSpan(it)
+        }
+        controllerSpan(it)
+        if (hasResponseSpan(SUCCESS)) {
+          responseSpan(it, SUCCESS)
+        }
+      }
+    }
+
+    and:
+    if (isDataStreamsEnabled()) {
+      StatsGroup first = TEST_DATA_STREAMS_WRITER.groups.find { it.parentHash == 0 }
+      verifyAll(first) {
+        edgeTags.containsAll(DSM_EDGE_TAGS)
+        edgeTags.size() == DSM_EDGE_TAGS.size()
+      }
+    }
+  }
+
   @Flaky(value = "https://github.com/DataDog/dd-trace-java/issues/4690", suites = ["MuleHttpServerForkedTest"])
   def "test QUERY_ENCODED_BOTH with response header x-ig-response-header tag mapping"() {
     setup:

@@ -84,6 +84,8 @@ public final class ConfigDefaults {
       new LinkedHashSet<>(asList(PropagationStyle.DATADOG));
   static final int DEFAULT_TRACE_BAGGAGE_MAX_ITEMS = 64;
   static final int DEFAULT_TRACE_BAGGAGE_MAX_BYTES = 8192;
+  static final List<String> DEFAULT_TRACE_BAGGAGE_TAG_KEYS =
+      Arrays.asList("user.id", "session.id", "account.id");
   static final boolean DEFAULT_JMX_FETCH_ENABLED = true;
   static final boolean DEFAULT_TRACE_AGENT_V05_ENABLED = false;
 

@@ -98,6 +98,7 @@ public final class TracerConfig {
   public static final String TRACE_PROPAGATION_EXTRACT_FIRST = "trace.propagation.extract.first";
   public static final String TRACE_BAGGAGE_MAX_ITEMS = "trace.baggage.max.items";
   public static final String TRACE_BAGGAGE_MAX_BYTES = "trace.baggage.max.bytes";
+  public static final String TRACE_BAGGAGE_TAG_KEYS = "trace.baggage.tag.keys";
 
   public static final String ENABLE_TRACE_AGENT_V05 = "trace.agent.v0.5.enabled";
 

@@ -151,6 +151,7 @@
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_ANALYTICS_ENABLED;
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_BAGGAGE_MAX_BYTES;
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_BAGGAGE_MAX_ITEMS;
+import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_BAGGAGE_TAG_KEYS;
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_CLOUD_PAYLOAD_TAGGING_SERVICES;
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_EXPERIMENTAL_FEATURES_ENABLED;
 import static datadog.trace.api.ConfigDefaults.DEFAULT_TRACE_HTTP_RESOURCE_REMOVE_TRAILING_SLASH;
@@ -583,6 +584,7 @@
 import static datadog.trace.api.config.TracerConfig.TRACE_ANALYTICS_ENABLED;
 import static datadog.trace.api.config.TracerConfig.TRACE_BAGGAGE_MAX_BYTES;
 import static datadog.trace.api.config.TracerConfig.TRACE_BAGGAGE_MAX_ITEMS;
+import static datadog.trace.api.config.TracerConfig.TRACE_BAGGAGE_TAG_KEYS;
 import static datadog.trace.api.config.TracerConfig.TRACE_CLIENT_IP_HEADER;
 import static datadog.trace.api.config.TracerConfig.TRACE_CLIENT_IP_RESOLVER_ENABLED;
 import static datadog.trace.api.config.TracerConfig.TRACE_CLOUD_PAYLOAD_TAGGING_MAX_DEPTH;
@@ -823,6 +825,7 @@ public static String getHostName() {
   private final boolean tracePropagationExtractFirst;
   private final int traceBaggageMaxItems;
   private final int traceBaggageMaxBytes;
+  private final List<String> traceBaggageTagKeys;
   private final int clockSyncPeriod;
   private final boolean logsInjectionEnabled;
 
@@ -1695,6 +1698,11 @@ private Config(final ConfigProvider configProvider, final InstrumenterConfig ins
         // If we have a new setting, we log a warning
         logOverriddenDeprecatedSettingWarning(PROPAGATION_STYLE_INJECT, injectOrigin, inject);
       }
+
+      // Parse the baggage tag keys configuration
+      traceBaggageTagKeys =
+          configProvider.getList(TRACE_BAGGAGE_TAG_KEYS, DEFAULT_TRACE_BAGGAGE_TAG_KEYS);
+
       // Now we can check if we should pick the default injection/extraction
 
       tracePropagationStylesToExtract =
@@ -2966,6 +2974,10 @@ public Map<String, String> getBaggageMapping() {
     return baggageMapping;
   }
 
+  public List<String> getTraceBaggageTagKeys() {
+    return traceBaggageTagKeys;
+  }
+
   public Map<String, String> getHttpServerPathResourceNameMapping() {
     return httpServerPathResourceNameMapping;
   }
@@ -5374,6 +5386,8 @@ public String toString() {
         + traceKeepLatencyThreshold
         + ", traceStrictWritesEnabled="
         + traceStrictWritesEnabled
+        + ", traceBaggageTagKeys="
+        + traceBaggageTagKeys
         + ", tracePropagationStylesToExtract="
         + tracePropagationStylesToExtract
         + ", tracePropagationStylesToInject="

@@ -175,6 +175,15 @@ public void putTag(final String key, final String value) {
     this.tags.set(key, value);
   }
 
+  public void putTagIfAbsent(final String key, final String value) {
+    if (this.tags == null) {
+      this.tags = TagMap.create(4);
+    }
+    if (!this.tags.containsKey(key)) {
+      this.tags.set(key, value);
+    }
+  }
+
   @Override
   public final int getSamplingPriority() {
     return samplingPriority;