Add default ExceptionEventExtractor

Author: trask

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/Instrumenter.java

@@ -16,6 +16,7 @@
 import io.opentelemetry.api.incubator.logs.ExtendedLogRecordBuilder;
 import io.opentelemetry.api.logs.LogRecordBuilder;
 import io.opentelemetry.api.logs.Logger;
+import io.opentelemetry.api.logs.Severity;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanBuilder;
 import io.opentelemetry.api.trace.SpanKind;
@@ -104,10 +105,6 @@ public static <REQUEST, RESPONSE> InstrumenterBuilder<REQUEST, RESPONSE> builder
   Instrumenter(InstrumenterBuilder<REQUEST, RESPONSE> builder) {
     this.instrumentationName = builder.instrumentationName;
     this.tracer = builder.buildTracer();
-    this.logger =
-        emitExceptionAsLogs() && builder.exceptionEventExtractor != null
-            ? builder.buildLogger()
-            : null;
     this.spanNameExtractor = builder.spanNameExtractor;
     this.spanKindExtractor = builder.spanKindExtractor;
     this.spanStatusExtractor = builder.spanStatusExtractor;
@@ -118,10 +115,20 @@ public static <REQUEST, RESPONSE> InstrumenterBuilder<REQUEST, RESPONSE> builder
     this.operationListenerAttributesExtractors =
         builder.operationListenerAttributesExtractors.toArray(new AttributesExtractor[0]);
     this.errorCauseExtractor = builder.errorCauseExtractor;
-    this.exceptionEventExtractor = builder.exceptionEventExtractor;
     this.propagateOperationListenersToOnEnd = builder.propagateOperationListenersToOnEnd;
     this.enabled = builder.enabled;
     this.spanSuppressor = builder.buildSpanSuppressor();
+
+    if (emitExceptionAsLogs()) {
+      this.logger = builder.buildLogger();
+      this.exceptionEventExtractor =
+          builder.exceptionEventExtractor != null
+              ? builder.exceptionEventExtractor
+              : defaultExceptionEventExtractor(builder.instrumentationName);
+    } else {
+      this.logger = null;
+      this.exceptionEventExtractor = builder.exceptionEventExtractor;
+    }
   }
 
   /**
@@ -350,6 +357,15 @@ private void emitExceptionLog(Context context, Throwable throwable, REQUEST requ
     logRecordBuilder.emit();
   }
 
+  private static <REQUEST> InternalExceptionEventExtractor<REQUEST> defaultExceptionEventExtractor(
+      String instrumentationName) {
+    String eventName = instrumentationName + ".exception";
+    return (logRecordBuilder, context, request) -> {
+      logRecordBuilder.setEventName(eventName);
+      logRecordBuilder.setSeverity(Severity.WARN);
+    };
+  }
+
   private static long getNanos(@Nullable Instant time) {
     if (time == null) {
       return System.nanoTime();

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/instrumenter/InstrumenterTest.java

@@ -449,6 +449,44 @@ void consumer_error_with_explicit_severity() {
     }
   }
 
+  @Test
+  void error_default_exception_event_extractor() {
+    // When no ExceptionEventExtractor is explicitly set, a default should be used
+    // that sets event name to instrumentationName + ".exception" and severity to WARN.
+    Instrumenter<Map<String, String>, Map<String, String>> instrumenter =
+        Instrumenter.<Map<String, String>, Map<String, String>>builder(
+                otelTesting.getOpenTelemetry(), "test", unused -> "span")
+            .buildInstrumenter();
+
+    Context context = instrumenter.start(Context.root(), REQUEST);
+    assertThat(Span.fromContext(context).getSpanContext().isValid()).isTrue();
+
+    IllegalStateException error = new IllegalStateException("test");
+    instrumenter.end(context, REQUEST, RESPONSE, error);
+
+    otelTesting
+        .assertTraces()
+        .hasTracesSatisfyingExactly(
+            trace ->
+                trace.hasSpansSatisfyingExactly(
+                    span ->
+                        span.hasName("span")
+                            .hasStatus(StatusData.error())
+                            .hasException(emitExceptionAsSpanEvents() ? error : null)));
+
+    if (emitExceptionAsLogs()) {
+      List<LogRecordData> logs = otelTesting.getLogRecords();
+      assertThat(logs).hasSize(1);
+      LogRecordData log = logs.get(0);
+      assertThat(log.getSeverity()).isEqualTo(Severity.WARN);
+      assertThat(log.getEventName()).isEqualTo("test.exception");
+      assertThat(log.getAttributes().get(EXCEPTION_TYPE))
+          .isEqualTo("java.lang.IllegalStateException");
+      assertThat(log.getAttributes().get(EXCEPTION_MESSAGE)).isEqualTo("test");
+      assertThat(log.getAttributes().get(EXCEPTION_STACKTRACE)).isNotNull();
+    }
+  }
+
   @Test
   void client_parent() {
     Instrumenter<Map<String, String>, Map<String, String>> instrumenter =