Support propagating OTel API created baggage via outgoing W3C headers (#9987)

Author: mcculls

dd-java-agent/agent-otel/otel-shim/src/main/java/datadog/opentelemetry/shim/baggage/OtelBaggageBuilder.java

@@ -35,6 +35,6 @@ public BaggageBuilder remove(@Nullable String key) {
 
   @Override
   public Baggage build() {
-    return new OtelBaggage(items);
+    return new OtelBaggage(new HashMap<>(items));
   }
 }

dd-java-agent/agent-otel/otel-shim/src/main/java/datadog/opentelemetry/shim/context/OtelContext.java

@@ -80,6 +80,12 @@ public <V> Context with(ContextKey<V> key, V value) {
       if (value instanceof OtelBaggage) {
         Baggage baggage = ((OtelBaggage) value).asAgentBaggage();
         return new OtelContext(delegate.with(baggage));
+      } else if (value instanceof io.opentelemetry.api.baggage.Baggage) {
+        Baggage baggage = Baggage.empty();
+        // transfer baggage to our internal container for propagation purposes
+        ((io.opentelemetry.api.baggage.Baggage) value)
+            .forEach((k, b) -> baggage.addItem(k, b.getValue()));
+        return new OtelContext(delegate.with(baggage));
       }
       // fall-through and store as non-datadog baggage
     }

dd-java-agent/instrumentation/opentelemetry/opentelemetry-1.4/src/test/groovy/opentelemetry14/context/ContextTest.groovy

@@ -338,43 +338,90 @@ class ContextTest extends InstrumentationSpecification {
     otelBaggageFromContext.isEmpty()
     otelBaggageFromContextOrNull == null
 
+    when:
+    def otelScope = Baggage.builder()
+      .put("foo", "otel_value_to_be_replaced")
+      .put("FOO","OTEL_UNTOUCHED")
+      .put("remove_me_key", "otel_remove_me_value")
+      .build()
+      .makeCurrent()
+    otelBaggage = Baggage.current()
+    otelBaggageFromContext = Baggage.fromContext(Context.current())
+    otelBaggageFromContextOrNull = Baggage.fromContextOrNull(Context.current())
+
+    then: "OTel baggage must be current"
+    otelBaggage != null
+    otelBaggage.size() == 3
+    otelBaggage.getEntryValue("foo") == "otel_value_to_be_replaced"
+    otelBaggage.getEntryValue("FOO") == "OTEL_UNTOUCHED"
+    otelBaggage.getEntryValue("remove_me_key") == "otel_remove_me_value"
+    otelBaggage.asMap() == otelBaggageFromContext.asMap()
+    otelBaggage.asMap() == otelBaggageFromContextOrNull.asMap()
+
     when:
     def ddContext = datadog.context.Context.current()
-    def ddBaggage = datadog.trace.bootstrap.instrumentation.api.Baggage.create([
-      "foo"           : "value_to_be_replaced",
-      "FOO"           : "UNTOUCHED",
-      "remove_me_key" : "remove_me_value"
-    ])
+    def ddBaggage = datadog.trace.bootstrap.instrumentation.api.Baggage.fromContext(ddContext)
+    ddBaggage.addItem("new_foo", "dd_new_value")
+    ddBaggage.addItem("foo", "dd_overwrite_value")
+    ddBaggage.removeItem("remove_me_key")
     def ddScope = ddContext.with(ddBaggage).attach()
     otelBaggage = Baggage.current()
     otelBaggageFromContext = Baggage.fromContext(Context.current())
     otelBaggageFromContextOrNull = Baggage.fromContextOrNull(Context.current())
 
+    then: "baggage must contain Datadog changes"
+    otelBaggage != null
+    otelBaggage.size() == 3
+    otelBaggage.getEntryValue("foo") == "dd_overwrite_value"
+    otelBaggage.getEntryValue("FOO") == "OTEL_UNTOUCHED"
+    otelBaggage.getEntryValue("new_foo") == "dd_new_value"
+    otelBaggage.asMap() == otelBaggageFromContext.asMap()
+    otelBaggage.asMap() == otelBaggageFromContextOrNull.asMap()
+
+    when:
+    ddScope.close()
+    otelScope.close()
+
+    then: "current baggage must be empty or null"
+    Baggage.current().isEmpty()
+
+    when:
+    ddContext = datadog.context.Context.current()
+    ddBaggage = datadog.trace.bootstrap.instrumentation.api.Baggage.create([
+      "foo"           : "dd_value_to_be_replaced",
+      "FOO"           : "DD_UNTOUCHED",
+      "remove_me_key" : "dd_remove_me_value"
+    ])
+    ddScope = ddContext.with(ddBaggage).attach()
+    otelBaggage = Baggage.current()
+    otelBaggageFromContext = Baggage.fromContext(Context.current())
+    otelBaggageFromContextOrNull = Baggage.fromContextOrNull(Context.current())
+
     then: "Datadog baggage must be current"
     otelBaggage != null
     otelBaggage.size() == 3
-    otelBaggage.getEntryValue("foo") == "value_to_be_replaced"
-    otelBaggage.getEntryValue("FOO") == "UNTOUCHED"
-    otelBaggage.getEntryValue("remove_me_key") == "remove_me_value"
+    otelBaggage.getEntryValue("foo") == "dd_value_to_be_replaced"
+    otelBaggage.getEntryValue("FOO") == "DD_UNTOUCHED"
+    otelBaggage.getEntryValue("remove_me_key") == "dd_remove_me_value"
     otelBaggage.asMap() == otelBaggageFromContext.asMap()
     otelBaggage.asMap() == otelBaggageFromContextOrNull.asMap()
 
     when:
     def builder = otelBaggage.toBuilder()
-    builder.put("new_foo", "new_value")
-    builder.put("foo", "overwrite_value")
+    builder.put("new_foo", "otel_new_value")
+    builder.put("foo", "otel_overwrite_value")
     builder.remove("remove_me_key")
-    def otelScope = builder.build().makeCurrent()
+    otelScope = builder.build().makeCurrent()
     otelBaggage = Baggage.current()
     otelBaggageFromContext = Baggage.fromContext(Context.current())
     otelBaggageFromContextOrNull = Baggage.fromContextOrNull(Context.current())
 
     then: "baggage must contain OTel changes"
     otelBaggage != null
     otelBaggage.size() == 3
-    otelBaggage.getEntryValue("foo") == "overwrite_value"
-    otelBaggage.getEntryValue("FOO") == "UNTOUCHED"
-    otelBaggage.getEntryValue("new_foo") == "new_value"
+    otelBaggage.getEntryValue("foo") == "otel_overwrite_value"
+    otelBaggage.getEntryValue("FOO") == "DD_UNTOUCHED"
+    otelBaggage.getEntryValue("new_foo") == "otel_new_value"
     otelBaggage.asMap() == otelBaggageFromContext.asMap()
     otelBaggage.asMap() == otelBaggageFromContextOrNull.asMap()