Implement fallback MDC implementation for JUL (#190)

Add fallback MDC for JUL

Author: SylvainJuge

ecs-logging-core/src/test/java/co/elastic/logging/AbstractEcsLoggingTest.java

@@ -171,7 +171,7 @@ void testThreadContext() throws Exception {
 
     @Test
     void testThreadContextStack() throws Exception {
-        if (putNdc("foo")) {
+        if (putMdc("foo")) {
             debug("test");
             assertThat(getAndValidateLastLogLine().get("tags").iterator().next().textValue()).isEqualTo("foo");
         }
@@ -223,7 +223,7 @@ public boolean putMdc(String key, String value) {
         return false;
     }
 
-    public boolean putNdc(String message) {
+    public boolean putMdc(String message) {
         return false;
     }
 

jboss-logmanager-ecs-formatter/src/test/java/co/elastic/logging/jboss/logmanager/JBossLogManagerTest.java

@@ -55,7 +55,7 @@ public boolean putMdc(String key, String value) {
     }
 
     @Override
-    public boolean putNdc(String message) {
+    public boolean putMdc(String message) {
         NDC.push(message);
         return true;
     }

jul-ecs-formatter/pom.xml

@@ -27,17 +27,5 @@
             <type>test-jar</type>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-            <version>1.7.30</version>
-            <optional>true</optional>
-        </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-jdk14</artifactId>
-            <version>1.7.30</version>
-            <scope>test</scope>
-        </dependency>
     </dependencies>
 </project>

jul-ecs-formatter/src/main/java/co/elastic/logging/jul/EcsFormatter.java

@@ -11,9 +11,9 @@
  * 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
@@ -24,20 +24,19 @@
  */
 package co.elastic.logging.jul;
 
+import co.elastic.logging.AdditionalField;
+import co.elastic.logging.EcsJsonSerializer;
+
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Formatter;
 import java.util.logging.LogManager;
 import java.util.logging.LogRecord;
 
-import co.elastic.logging.AdditionalField;
-import co.elastic.logging.EcsJsonSerializer;
-
 public class EcsFormatter extends Formatter {
 
     private static final String UNKNOWN_FILE = "<Unknown>";
-    private static final MdcSupplier mdcSupplier = MdcSupplier.Resolver.INSTANCE.resolve();
-    
+
     private boolean stackTraceAsArray;
     private String serviceName;
     private String serviceVersion;
@@ -52,8 +51,8 @@ public class EcsFormatter extends Formatter {
      */
     public EcsFormatter() {
         serviceName = getProperty("co.elastic.logging.jul.EcsFormatter.serviceName", null);
-        serviceVersion= getProperty("co.elastic.logging.jul.EcsFormatter.serviceVersion", null);
-        serviceEnvironment= getProperty("co.elastic.logging.jul.EcsFormatter.serviceEnvironment", null);
+        serviceVersion = getProperty("co.elastic.logging.jul.EcsFormatter.serviceVersion", null);
+        serviceEnvironment = getProperty("co.elastic.logging.jul.EcsFormatter.serviceEnvironment", null);
         serviceNodeName = getProperty("co.elastic.logging.jul.EcsFormatter.serviceNodeName", null);
         includeOrigin = Boolean.parseBoolean(getProperty("co.elastic.logging.jul.EcsFormatter.includeOrigin", "false"));
         stackTraceAsArray = Boolean.parseBoolean(getProperty("co.elastic.logging.jul.EcsFormatter.stackTraceAsArray", "false"));
@@ -70,7 +69,7 @@ public String format(final LogRecord record) {
         EcsJsonSerializer.serializeFormattedMessage(builder, super.formatMessage(record));
         EcsJsonSerializer.serializeEcsVersion(builder);
         EcsJsonSerializer.serializeAdditionalFields(builder, additionalFields);
-        EcsJsonSerializer.serializeMDC(builder, mdcSupplier.getMDC());
+        EcsJsonSerializer.serializeMDC(builder, JulMdc.getEntries());
         EcsJsonSerializer.serializeServiceName(builder, serviceName);
         EcsJsonSerializer.serializeServiceVersion(builder, serviceVersion);
         EcsJsonSerializer.serializeServiceEnvironment(builder, serviceEnvironment);
@@ -116,7 +115,7 @@ public void setServiceNodeName(final String serviceNodeName) {
     public void setStackTraceAsArray(final boolean stackTraceAsArray) {
         this.stackTraceAsArray = stackTraceAsArray;
     }
-    
+
     public void setEventDataset(String eventDataset) {
         this.eventDataset = eventDataset;
     }

jul-ecs-formatter/src/main/java/co/elastic/logging/jul/JulMdc.java

@@ -0,0 +1,71 @@
+/*-
+ * #%L
+ * Java ECS logging
+ * %%
+ * Copyright (C) 2019 - 2022 Elastic and contributors
+ * %%
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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.
+ * #L%
+ */
+package co.elastic.logging.jul;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * MDC implementation for JUL as it does not have one.
+ * This MDC will be used by the APM agent for logs correlation.
+ */
+public class JulMdc {
+
+    /**
+     * This MDC is currently used with 3 key/values: trace,transaction and error IDs.
+     */
+    private static final int INITIAL_CAPACITY = 4;
+
+    private static final ThreadLocal<Map<String, String>> tlm = new ThreadLocal<Map<String, String>>();
+
+    public static void put(String key, String value) {
+        Map<String, String> map = tlm.get();
+        if (map == null) {
+            map = new HashMap<String, String>(INITIAL_CAPACITY);
+            tlm.set(map);
+        }
+        map.put(key, value);
+    }
+
+    public static void remove(String key) {
+        Map<String, String> entries = tlm.get();
+        if (entries != null) {
+            entries.remove(key);
+        }
+    }
+
+    /**
+     * Get the MDC entries, the returned map should not escape the current thread as the map implementation is not
+     * thread-safe and thus concurrent modification is not supported.
+     *
+     * @return map of MDC entries
+     */
+    static Map<String, String> getEntries() {
+        Map<String, String> entries = tlm.get();
+        return entries == null ? Collections.<String, String>emptyMap() : entries;
+    }
+
+}

jul-ecs-formatter/src/main/java/co/elastic/logging/jul/MdcSupplier.java

@@ -11,9 +11,9 @@
  * 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
@@ -30,7 +30,6 @@
 import com.fasterxml.jackson.databind.JsonNode;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.slf4j.MDC;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -71,9 +70,9 @@ public void publish(LogRecord record) {
     }
 
     private EcsFormatter formatter;
-    
+
     private final Logger logger = Logger.getLogger("");
-    
+
     private final ByteArrayOutputStream out = new ByteArrayOutputStream();
 
     private LogRecord record;
@@ -85,7 +84,7 @@ public void debug(String message) {
 
     @Override
     public boolean putMdc(String key, String value) {
-        MDC.put(key, value);
+        JulMdc.put(key, value);
         return true;
     }
 
@@ -103,7 +102,7 @@ public void debug(String message, Object... logParams) {
     public void error(String message, Throwable t) {
         logger.log(Level.SEVERE, message, t);
     }
-    
+
     @Override
     public JsonNode getLastLogLine() throws IOException {
         return objectMapper.readTree(out.toString());
@@ -153,7 +152,7 @@ void testAdditionalFieldsAsList() throws Exception {
         formatter.setAdditionalFields(List.of(new AdditionalField("key1", "value1"), new AdditionalField("key2", "value2")));
         super.testAdditionalFields();
     }
-    
+
     private void clearHandlers() {
         for (Handler handler : logger.getHandlers()) {
             logger.removeHandler(handler);

jul-ecs-formatter/src/test/java/co/elastic/logging/jul/JulLoggingTest.java

@@ -0,0 +1,69 @@
+/*-
+ * #%L
+ * Java ECS logging
+ * %%
+ * Copyright (C) 2019 - 2022 Elastic and contributors
+ * %%
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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.
+ * #L%
+ */
+package co.elastic.logging.jul;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class JulMdcTest {
+
+    @BeforeEach
+    void before(){
+        // prevently empty if any other test have left something
+        JulMdc.getEntries().clear();
+    }
+
+    @AfterEach
+    void after() {
+        JulMdc.getEntries().clear();
+        assertThat(JulMdc.getEntries()).isEmpty();
+    }
+
+    @Test
+    void emptyMdc() {
+        Map<String, String> entries = JulMdc.getEntries();
+        assertThat(entries).isEmpty();
+
+        assertThat(JulMdc.getEntries()).isSameAs(entries);
+
+        // should be a no-op
+        JulMdc.remove("missing");
+    }
+
+    @Test
+    void putRemoveSingleEntry() {
+        JulMdc.put("hello", "world");
+        assertThat(JulMdc.getEntries()).containsEntry("hello", "world");
+
+        JulMdc.remove("hello");
+        assertThat(JulMdc.getEntries()).isEmpty();
+    }
+
+}