Add logback appender

bom-alpha/build.gradle.kts

@@ -13,10 +13,11 @@ javaPlatform {
 }
 
 val otelVersion: String by project
+val otelAlphaVersion: String by project
 
 dependencies {
   api(platform("io.opentelemetry:opentelemetry-bom:${otelVersion}"))
-  api(platform("io.opentelemetry:opentelemetry-bom-alpha:${otelVersion}-alpha"))
+  api(platform("io.opentelemetry:opentelemetry-bom-alpha:${otelAlphaVersion}"))
 }
 
 dependencies {

dependencyManagement/build.gradle.kts

@@ -14,6 +14,7 @@ rootProject.extra["versions"] = dependencyVersions
 val otelVersion = "1.10.0-rc.1"
 val otelAlphaVersion = "1.10.0-alpha-rc.1"
 rootProject.extra["otelVersion"] = otelVersion
+rootProject.extra["otelAlphaVersion"] = otelAlphaVersion
 
 // Need both BOM and -all
 val groovyVersion = "3.0.9"

instrumentation/logback/logback-appender-1.0/library/README.md

@@ -0,0 +1,80 @@
+# Logback Appender
+
+This module provides a Logback [appender](https://logback.qos.ch/manual/appenders.html) which
+forwards Logback log events to
+the [OpenTelemetry Log SDK](https://github.com/open-telemetry/opentelemetry-java/tree/main/sdk/logs)
+
+To use it, add the following modules to your application's classpath.
+
+Replace `OPENTELEMETRY_VERSION` with the latest
+stable [release](https://search.maven.org/search?q=g:io.opentelemetry.instrumentation).
+
+**Maven**
+
+```xml
+<dependencies>
+  <dependency>
+    <groupId>io.opentelemetry.instrumentation</groupId>
+    <artifactId>opentelemetry-logback-appender-1.0</artifactId>
+    <version>OPENTELEMETRY_VERSION</version>
+    <scope>runtime</scope>
+  </dependency>
+  <dependency>
+    <!-- The SDK appender is required to configure the appender with the OpenTelemetry Log SDK -->
+    <groupId>io.opentelemetry.instrumentation</groupId>
+    <artifactId>opentelemetry-instrumentation-sdk-appender</artifactId>
+    <version>OPENTELEMETRY_VERSION</version>
+  </dependency>
+</dependencies>
+```
+
+**Gradle**
+
+```kotlin
+dependencies {
+  runtimeOnly("io.opentelemetry.instrumentation:opentelemetry-logback-appender-1.0:OPENTELEMETRY_VERSION")
+  // The SDK appender is required to configure the appender with the OpenTelemetry Log SDK
+  implementation("io.opentelemetry.instrumentation:opentelemetry-instrumentation-sdk-appender:OPENTELEMETRY_VERSION")
+}
+```
+
+The following demonstrates how you might configure the appender in your `logback.xml` configuration:
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+
+  <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+    <encoder>
+      <pattern>
+        %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+      </pattern>
+    </encoder>
+  </appender>
+  <appender name="OpenTelemetry" class="io.opentelemetry.instrumentation.logback.appender.v1_0.OpenTelemetryAppender">
+  </appender>
+
+  <root level="INFO">
+    <appender-ref ref="console"/>
+    <appender-ref ref="OpenTelemetry" />
+  </root>
+
+</configuration>
+```
+
+Next, associate the `OpenTelemetry` configured via `logback.xml` with a `SdkLogEmitterProvider` in
+your application:
+
+```
+SdkLogEmitterProvider logEmitterProvider =
+  SdkLogEmitterProvider.builder()
+    .setResource(Resource.create(...))
+    .addLogProcessor(...)
+    .build();
+GlobalLogEmitterProvider.set(DelegatingLogEmitterProvider.from(logEmitterProvider));
+```
+
+In this example Logback log events will be sent to both the console appender and
+the `OpenTelemetryAppender`, which will drop the logs until `GlobalLogEmitterProvider.set(..)` is
+called. Once initialized, logs will be emitted to a `LogEmitter` obtained from
+the `SdkLogEmitterProvider`.

instrumentation/logback/logback-appender-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/appender/v1_0/OpenTelemetryAppender.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.logback.appender.v1_0;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.AppenderBase;
+import io.opentelemetry.instrumentation.logback.appender.v1_0.internal.LoggingEventMapper;
+
+public class OpenTelemetryAppender extends AppenderBase<ILoggingEvent> {
+
+  public OpenTelemetryAppender() {}
+
+  @Override
+  protected void append(ILoggingEvent event) {
+    LoggingEventMapper.INSTANCE.capture(event);
+  }
+}

instrumentation/logback/logback-appender-1.0/library/src/test/java/io/opentelemetry/instrumentation/logback/appender/v1_0/OpenTelemetryAppenderConfigTest.java

@@ -0,0 +1,153 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.logback.appender.v1_0;
+
+import static org.assertj.core.api.AssertionsForInterfaceTypes.assertThat;
+
+import io.opentelemetry.api.common.AttributeKey;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanContext;
+import io.opentelemetry.context.Scope;
+import io.opentelemetry.instrumentation.api.appender.GlobalLogEmitterProvider;
+import io.opentelemetry.instrumentation.sdk.appender.DelegatingLogEmitterProvider;
+import io.opentelemetry.sdk.common.InstrumentationLibraryInfo;
+import io.opentelemetry.sdk.logs.SdkLogEmitterProvider;
+import io.opentelemetry.sdk.logs.data.LogData;
+import io.opentelemetry.sdk.logs.data.Severity;
+import io.opentelemetry.sdk.logs.export.InMemoryLogExporter;
+import io.opentelemetry.sdk.logs.export.SimpleLogProcessor;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import io.opentelemetry.semconv.trace.attributes.SemanticAttributes;
+import java.time.Instant;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import org.assertj.core.api.AssertionsForClassTypes;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.MDC;
+
+class OpenTelemetryAppenderConfigTest {
+
+  private static final Logger logger = LoggerFactory.getLogger("TestLogger");
+
+  private static InMemoryLogExporter logExporter;
+  private static Resource resource;
+  private static InstrumentationLibraryInfo instrumentationLibraryInfo;
+
+  @BeforeAll
+  static void setupAll() {
+    logExporter = InMemoryLogExporter.create();
+    resource = Resource.getDefault();
+    instrumentationLibraryInfo = InstrumentationLibraryInfo.create("TestLogger", null);
+
+    SdkLogEmitterProvider logEmitterProvider =
+        SdkLogEmitterProvider.builder()
+            .setResource(resource)
+            .addLogProcessor(SimpleLogProcessor.create(logExporter))
+            .build();
+
+    GlobalLogEmitterProvider.resetForTest();
+    GlobalLogEmitterProvider.set(DelegatingLogEmitterProvider.from(logEmitterProvider));
+  }
+
+  @BeforeEach
+  void setup() {
+    logExporter.reset();
+  }
+
+  @Test
+  void logNoSpan() {
+    logger.info("log message 1");
+
+    List<LogData> logDataList = logExporter.getFinishedLogItems();
+    assertThat(logDataList).hasSize(1);
+    LogData logData = logDataList.get(0);
+    assertThat(logData.getResource()).isEqualTo(resource);
+    assertThat(logData.getInstrumentationLibraryInfo()).isEqualTo(instrumentationLibraryInfo);
+    assertThat(logData.getBody().asString()).isEqualTo("log message 1");
+    assertThat(logData.getAttributes()).isEqualTo(Attributes.empty());
+  }
+
+  @Test
+  void logWithSpan() {
+    Span span1 = runWithSpan("span1", () -> logger.info("log message 1"));
+
+    logger.info("log message 2");
+
+    Span span2 = runWithSpan("span2", () -> logger.info("log message 3"));
+
+    List<LogData> logDataList = logExporter.getFinishedLogItems();
+    assertThat(logDataList).hasSize(3);
+    assertThat(logDataList.get(0).getSpanContext()).isEqualTo(span1.getSpanContext());
+    assertThat(logDataList.get(1).getSpanContext()).isEqualTo(SpanContext.getInvalid());
+    assertThat(logDataList.get(2).getSpanContext()).isEqualTo(span2.getSpanContext());
+  }
+
+  private static Span runWithSpan(String spanName, Runnable runnable) {
+    Span span = SdkTracerProvider.builder().build().get("tracer").spanBuilder(spanName).startSpan();
+    try (Scope ignored = span.makeCurrent()) {
+      runnable.run();
+    } finally {
+      span.end();
+    }
+    return span;
+  }
+
+  @Test
+  void logWithExtras() {
+    Instant start = Instant.now();
+    logger.info("log message 1", new IllegalStateException("Error!"));
+
+    List<LogData> logDataList = logExporter.getFinishedLogItems();
+    assertThat(logDataList).hasSize(1);
+    LogData logData = logDataList.get(0);
+    assertThat(logData.getResource()).isEqualTo(resource);
+    assertThat(logData.getInstrumentationLibraryInfo()).isEqualTo(instrumentationLibraryInfo);
+    assertThat(logData.getBody().asString()).isEqualTo("log message 1");
+    assertThat(logData.getEpochNanos())
+        .isGreaterThan(TimeUnit.MILLISECONDS.toNanos(start.toEpochMilli()))
+        .isLessThan(TimeUnit.MILLISECONDS.toNanos(Instant.now().toEpochMilli()));
+    assertThat(logData.getSeverity()).isEqualTo(Severity.INFO);
+    assertThat(logData.getSeverityText()).isEqualTo("INFO");
+    assertThat(logData.getAttributes().size()).isEqualTo(3);
+    assertThat(logData.getAttributes().get(SemanticAttributes.EXCEPTION_TYPE))
+        .isEqualTo(IllegalStateException.class.getName());
+    assertThat(logData.getAttributes().get(SemanticAttributes.EXCEPTION_MESSAGE))
+        .isEqualTo("Error!");
+    assertThat(logData.getAttributes().get(SemanticAttributes.EXCEPTION_STACKTRACE))
+        .contains("logWithExtras");
+  }
+
+  @Test
+  void logContextData() {
+    MDC.put("key1", "val1");
+    MDC.put("key2", "val2");
+    try {
+      logger.info("log message 1");
+    } finally {
+      MDC.clear();
+    }
+
+    List<LogData> logDataList = logExporter.getFinishedLogItems();
+    assertThat(logDataList).hasSize(1);
+    LogData logData = logDataList.get(0);
+    assertThat(logData.getResource()).isEqualTo(resource);
+    assertThat(logData.getInstrumentationLibraryInfo()).isEqualTo(instrumentationLibraryInfo);
+    assertThat(logData.getBody().asString()).isEqualTo("log message 1");
+    assertThat(logData.getAttributes().size()).isEqualTo(2);
+    AssertionsForClassTypes.assertThat(
+            logData.getAttributes().get(AttributeKey.stringKey("logback.mdc.key1")))
+        .isEqualTo("val1");
+    AssertionsForClassTypes.assertThat(
+            logData.getAttributes().get(AttributeKey.stringKey("logback.mdc.key2")))
+        .isEqualTo("val2");
+  }
+}

instrumentation/logback/logback-appender-1.0/library/src/test/resources/logback-test.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+
+  <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+    <encoder>
+      <pattern>
+        %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+      </pattern>
+    </encoder>
+  </appender>
+  <appender name="OpenTelemetry" class="io.opentelemetry.instrumentation.logback.appender.v1_0.OpenTelemetryAppender">
+  </appender>
+
+  <root level="INFO">
+    <appender-ref ref="console"/>
+    <appender-ref ref="OpenTelemetry" />
+  </root>
+
+</configuration>