Inject span context into log4j2 2.13.2+ context.

instrumentation/log4j/log4j-2.13.2/library/log4j-2.13.2-library.gradle

@@ -0,0 +1,25 @@
+ext {
+  minJavaVersionForTests = JavaVersion.VERSION_1_8
+  javaSubPackage = 'log4j.v2_13_2'
+}
+
+apply from: "$rootDir/gradle/instrumentation-library.gradle"
+apply plugin: 'org.unbroken-dome.test-sets'
+
+testSets {
+  latestDepTest {
+    dirName = 'test'
+  }
+}
+
+dependencies {
+  compileOnly group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.13.2'
+
+  annotationProcessor deps.autoservice
+  compileOnly deps.autoservice
+
+  testImplementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.13.2'
+  testAnnotationProcessor group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.13.2'
+
+  latestDepTestImplementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: '+'
+}

instrumentation/log4j/log4j-2.13.2/library/src/main/java/io/opentelemetry/instrumentation/log4j/v2_13_2/OpenTelemetryContextDataProvider.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.instrumentation.log4j.v2_13_2;
+
+import com.google.auto.service.AutoService;
+import io.opentelemetry.trace.Span;
+import io.opentelemetry.trace.SpanContext;
+import io.opentelemetry.trace.TracingContextUtils;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.logging.log4j.core.util.ContextDataProvider;
+
+@AutoService(ContextDataProvider.class)
+public class OpenTelemetryContextDataProvider implements ContextDataProvider {
+  @Override
+  public Map<String, String> supplyContextData() {
+    Span currentSpan = TracingContextUtils.getCurrentSpan();
+    if (currentSpan == null || !currentSpan.getContext().isValid()) {
+      return Collections.emptyMap();
+    }
+
+    Map<String, String> contextData = new HashMap<>();
+    SpanContext spanContext = currentSpan.getContext();
+    contextData.put("traceId", spanContext.getTraceId().toLowerBase16());
+    contextData.put("spanId", spanContext.getSpanId().toLowerBase16());
+    return contextData;
+  }
+}

instrumentation/log4j/log4j-2.13.2/library/src/test/groovy/io/opentelemetry/instrumentation/log4j/v2_13_2/Log4j2Test.groovy

@@ -0,0 +1,84 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.instrumentation.log4j.v2_13_2
+
+import io.opentelemetry.auto.test.utils.TraceUtils
+import io.opentelemetry.trace.Span
+import io.opentelemetry.trace.TracingContextUtils
+import org.apache.logging.log4j.LogManager
+import org.apache.logging.log4j.Logger
+import spock.lang.Specification
+
+class Log4j2Test extends Specification {
+
+  private static final Logger logger = LogManager.getLogger("TestLogger")
+
+  def cleanup() {
+    ListAppender.get().clearEvents()
+  }
+
+  def "no ids when no span"() {
+    when:
+    logger.info("log message 1")
+    logger.info("log message 2")
+
+    def events = ListAppender.get().getEvents()
+
+    then:
+    events.size() == 2
+    events[0].message.formattedMessage == "log message 1"
+    events[0].getContextData().getValue("traceId") == null
+    events[0].getContextData().getValue("spanId") == null
+
+    events[1].message.formattedMessage == "log message 2"
+    events[1].getContextData().getValue("traceId") == null
+    events[1].getContextData().getValue("spanId") == null
+  }
+
+  def "ids when span"() {
+    when:
+    Span span1
+    TraceUtils.runUnderTrace("test") {
+      span1 = TracingContextUtils.currentSpan
+      logger.info("log message 1")
+    }
+
+    logger.info("log message 2")
+
+    Span span2
+    TraceUtils.runUnderTrace("test 2") {
+      span2 = TracingContextUtils.currentSpan
+      logger.info("log message 3")
+    }
+
+    def events = ListAppender.get().getEvents()
+
+    then:
+    events.size() == 3
+    events[0].message.formattedMessage == "log message 1"
+    events[0].getContextData().getValue("traceId") == span1.context.traceId.toLowerBase16()
+    events[0].getContextData().getValue("spanId") == span1.context.spanId.toLowerBase16()
+
+    events[1].message.formattedMessage == "log message 2"
+    events[1].getContextData().getValue("traceId") == null
+    events[1].getContextData().getValue("spanId") == null
+
+    events[2].message.formattedMessage == "log message 3"
+    events[2].getContextData().getValue("traceId") == span2.context.traceId.toLowerBase16()
+    events[2].getContextData().getValue("spanId") == span2.context.spanId.toLowerBase16()
+  }
+}

instrumentation/log4j/log4j-2.13.2/library/src/test/java/io/opentelemetry/instrumentation/log4j/v2_13_2/ListAppender.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.instrumentation.log4j.v2_13_2;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import org.apache.logging.log4j.core.Appender;
+import org.apache.logging.log4j.core.Core;
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.appender.AbstractAppender;
+import org.apache.logging.log4j.core.config.Property;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+
+@Plugin(
+    name = "ListAppender",
+    category = Core.CATEGORY_NAME,
+    elementType = Appender.ELEMENT_TYPE,
+    printObject = true)
+public class ListAppender extends AbstractAppender {
+
+  public static ListAppender get() {
+    return INSTANCE;
+  }
+
+  private static final ListAppender INSTANCE = new ListAppender();
+
+  private final List<LogEvent> events = Collections.synchronizedList(new ArrayList<>());
+
+  public ListAppender() {
+    super("ListAppender", null, null, true, Property.EMPTY_ARRAY);
+  }
+
+  public List<LogEvent> getEvents() {
+    return events;
+  }
+
+  public void clearEvents() {
+    events.clear();
+  }
+
+  @Override
+  public void append(LogEvent logEvent) {
+    events.add(logEvent);
+  }
+
+  @PluginFactory
+  public static ListAppender createAppender(@PluginAttribute("name") String name) {
+    if (!name.equals("ListAppender")) {
+      throw new IllegalArgumentException(
+          "Use name=\"ListAppender\" in log4j2-test.xml instead of " + name);
+    }
+    return INSTANCE;
+  }
+}

instrumentation/log4j/log4j-2.13.2/library/src/test/resources/log4j2-test.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN" packages="com.example.appender">
+  <Appenders>
+    <Console name="Console" target="SYSTEM_OUT">
+      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
+    </Console>
+    <ListAppender name="ListAppender" />
+  </Appenders>
+  <Loggers>
+    <Logger name="TestLogger" level="All">
+      <AppenderRef ref="ListAppender" level="All" />
+    </Logger>
+    <Root>
+      <AppenderRef ref="Console" level="All" />
+    </Root>
+  </Loggers>
+</Configuration>

settings.gradle

@@ -112,6 +112,7 @@ include ':instrumentation:lettuce:lettuce-5.0'
 include ':instrumentation:lettuce:lettuce-5.1'
 include ':instrumentation:log4j:log4j-1.1'
 include ':instrumentation:log4j:log4j-2.0'
+include ':instrumentation:log4j:log4j-2.13.2:library'
 include ':instrumentation:logback-1.0'
 include ':instrumentation:mongo:mongo-3.1'
 include ':instrumentation:mongo:mongo-3.7'