Split off YAML configuration into its own module

This splits `YamlConfiguration` into its own module and removes
`jackson-dataformat-yaml` from `log4j-core`'s optional dependencies.

Author: ppkarwasz

log4j-config-yaml/pom.xml

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>org.apache.logging.log4j</groupId>
+    <artifactId>log4j</artifactId>
+    <version>${revision}</version>
+    <relativePath>../log4j-parent</relativePath>
+  </parent>
+
+  <artifactId>log4j-config-yaml</artifactId>
+
+  <dependencies>
+
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-core</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>com.fasterxml.jackson.dataformat</groupId>
+      <artifactId>jackson-dataformat-yaml</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-core-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <configuration>
+          <annotationProcessorPaths combine.children="append">
+            <path>
+              <groupId>org.apache.logging.log4j</groupId>
+              <artifactId>log4j-plugin-processor</artifactId>
+              <version>${project.version}</version>
+            </path>
+          </annotationProcessorPaths>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

log4j-core/src/main/java/org/apache/logging/log4j/core/config/yaml/YamlConfiguration.java renamed to log4j-config-yaml/src/main/java/org/apache/logging/log4j/core/config/yaml/YamlConfiguration.java

@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.logging.log4j.core.config;
+package org.apache.logging.log4j.config.yaml;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
@@ -24,6 +24,7 @@
 import org.apache.logging.log4j.core.appender.rolling.SizeBasedTriggeringPolicy;
 import org.apache.logging.log4j.core.appender.rolling.TimeBasedTriggeringPolicy;
 import org.apache.logging.log4j.core.appender.rolling.TriggeringPolicy;
+import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Tag;

log4j-core/src/main/java/org/apache/logging/log4j/core/config/yaml/YamlConfigurationFactory.java renamed to log4j-config-yaml/src/main/java/org/apache/logging/log4j/core/config/yaml/YamlConfigurationFactory.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.
+ */
+package org.apache.logging.log4j.config.yaml;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.AbstractConfigurationFactoryTest;
+import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
+import org.apache.logging.log4j.test.junit.TempLoggingDir;
+import org.junit.jupiter.api.Test;
+
+class YamlConfigurationFactoryTest extends AbstractConfigurationFactoryTest {
+
+    @TempLoggingDir
+    private static Path loggingPath;
+
+    @Test
+    @LoggerContextSource("YamlConfigurationFactoryTest.yaml")
+    void yamlConfiguration(final LoggerContext context) throws IOException {
+        checkConfiguration(context);
+        final Path logFile = loggingPath.resolve("test-yaml.log");
+        checkFileLogger(context, logFile);
+    }
+}

log4j-core/src/main/java/org/apache/logging/log4j/core/config/yaml/package-info.java renamed to log4j-config-yaml/src/main/java/org/apache/logging/log4j/core/config/yaml/package-info.java

@@ -0,0 +1,86 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.
+ */
+package org.apache.logging.log4j.core.config;
+
+import static org.apache.logging.log4j.util.Unbox.box;
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.Appender;
+import org.apache.logging.log4j.core.Filter;
+import org.apache.logging.log4j.core.Logger;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.appender.ConsoleAppender;
+import org.apache.logging.log4j.core.filter.ThreadContextMapFilter;
+import org.apache.logging.log4j.util.Strings;
+
+/**
+ * Common base class for configuration factory tests.
+ */
+public abstract class AbstractConfigurationFactoryTest {
+
+    private static final String LOGGER_NAME = "org.apache.logging.log4j.test1.Test";
+    private static final String FILE_LOGGER_NAME = "org.apache.logging.log4j.test2.Test";
+    private static final String APPENDER_NAME = "STDOUT";
+
+    /**
+     * Runs various configuration checks on a configured LoggerContext that should match the equivalent configuration in
+     * {@code log4j-test1.xml}.
+     */
+    protected static void checkConfiguration(final LoggerContext context) {
+        final Configuration configuration = context.getConfiguration();
+        final Map<String, Appender> appenders = configuration.getAppenders();
+        // these used to be separate tests
+        assertAll(
+                () -> assertNotNull(appenders),
+                () -> assertEquals(3, appenders.size()),
+                () -> assertNotNull(configuration.getLoggerContext()),
+                () -> assertEquals(configuration.getRootLogger(), configuration.getLoggerConfig(Strings.EMPTY)),
+                () -> assertThrows(NullPointerException.class, () -> configuration.getLoggerConfig(null)));
+
+        final Logger logger = context.getLogger(LOGGER_NAME);
+        assertEquals(Level.DEBUG, logger.getLevel());
+
+        assertEquals(1, logger.filterCount());
+        final Iterator<Filter> filterIterator = logger.getFilters();
+        assertTrue(filterIterator.hasNext());
+        assertTrue(filterIterator.next() instanceof ThreadContextMapFilter);
+
+        final Appender appender = appenders.get(APPENDER_NAME);
+        assertTrue(appender instanceof ConsoleAppender);
+        assertEquals(APPENDER_NAME, appender.getName());
+    }
+
+    protected static void checkFileLogger(final LoggerContext context, final Path logFile) throws IOException {
+        final long currentThreadId = Thread.currentThread().getId();
+        final Logger logger = context.getLogger(FILE_LOGGER_NAME);
+        logger.debug("Greetings from ConfigurationFactoryTest in thread#{}", box(currentThreadId));
+        final List<String> lines = Files.readAllLines(logFile);
+        assertEquals(1, lines.size());
+        assertTrue(lines.get(0).endsWith(Long.toString(currentThreadId)));
+    }
+}

log4j-core-test/src/test/java/org/apache/logging/log4j/core/config/MultipleTriggeringPolicyTest.java renamed to log4j-config-yaml/src/test/java/org/apache/logging/log4j/config/yaml/MultipleTriggeringPolicyTest.java

@@ -16,78 +16,19 @@
  */
 package org.apache.logging.log4j.core.config;
 
-import static org.apache.logging.log4j.util.Unbox.box;
-import static org.junit.jupiter.api.Assertions.assertAll;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 import java.io.IOException;
-import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
-import org.apache.logging.log4j.Level;
-import org.apache.logging.log4j.core.Appender;
-import org.apache.logging.log4j.core.Filter;
-import org.apache.logging.log4j.core.Logger;
 import org.apache.logging.log4j.core.LoggerContext;
-import org.apache.logging.log4j.core.appender.ConsoleAppender;
-import org.apache.logging.log4j.core.filter.ThreadContextMapFilter;
 import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
 import org.apache.logging.log4j.test.junit.TempLoggingDir;
-import org.apache.logging.log4j.util.Strings;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 
-class ConfigurationFactoryTest {
-
-    static final String LOGGER_NAME = "org.apache.logging.log4j.test1.Test";
-    static final String FILE_LOGGER_NAME = "org.apache.logging.log4j.test2.Test";
-    static final String APPENDER_NAME = "STDOUT";
+class ConfigurationFactoryTest extends AbstractConfigurationFactoryTest {
 
     @TempLoggingDir
     private static Path loggingPath;
 
-    /**
-     * Runs various configuration checks on a configured LoggerContext that should match the equivalent configuration in
-     * {@code log4j-test1.xml}.
-     */
-    static void checkConfiguration(final LoggerContext context) {
-        final Configuration configuration = context.getConfiguration();
-        final Map<String, Appender> appenders = configuration.getAppenders();
-        // these used to be separate tests
-        assertAll(
-                () -> assertNotNull(appenders),
-                () -> assertEquals(3, appenders.size()),
-                () -> assertNotNull(configuration.getLoggerContext()),
-                () -> assertEquals(configuration.getRootLogger(), configuration.getLoggerConfig(Strings.EMPTY)),
-                () -> assertThrows(NullPointerException.class, () -> configuration.getLoggerConfig(null)));
-
-        final Logger logger = context.getLogger(LOGGER_NAME);
-        assertEquals(Level.DEBUG, logger.getLevel());
-
-        assertEquals(1, logger.filterCount());
-        final Iterator<Filter> filterIterator = logger.getFilters();
-        assertTrue(filterIterator.hasNext());
-        assertTrue(filterIterator.next() instanceof ThreadContextMapFilter);
-
-        final Appender appender = appenders.get(APPENDER_NAME);
-        assertTrue(appender instanceof ConsoleAppender);
-        assertEquals(APPENDER_NAME, appender.getName());
-    }
-
-    static void checkFileLogger(final LoggerContext context, final Path logFile) throws IOException {
-        final long currentThreadId = Thread.currentThread().getId();
-        final Logger logger = context.getLogger(FILE_LOGGER_NAME);
-        logger.debug("Greetings from ConfigurationFactoryTest in thread#{}", box(currentThreadId));
-        final List<String> lines = Files.readAllLines(logFile);
-        assertEquals(1, lines.size());
-        assertTrue(lines.get(0).endsWith(Long.toString(currentThreadId)));
-    }
-
     @Test
     @LoggerContextSource("log4j-test1.xml")
     void xml(final LoggerContext context) throws IOException {
@@ -113,15 +54,6 @@ void json(final LoggerContext context) throws IOException {
         checkFileLogger(context, logFile);
     }
 
-    @Test
-    @Tag("yaml")
-    @LoggerContextSource("log4j-test1.yaml")
-    void yaml(final LoggerContext context) throws IOException {
-        checkConfiguration(context);
-        final Path logFile = loggingPath.resolve("test-yaml.log");
-        checkFileLogger(context, logFile);
-    }
-
     @Test
     @LoggerContextSource("log4j-test1.properties")
     void properties(final LoggerContext context) throws IOException {

log4j-config-yaml/src/test/java/org/apache/logging/log4j/config/yaml/YamlConfigurationFactoryTest.java

@@ -25,12 +25,8 @@
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.appender.FileAppender;
 import org.apache.logging.log4j.core.layout.PatternLayout;
-import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
-import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 
-@Tag("yaml")
-@LoggerContextSource("log4j2-2134.yaml")
 public class JiraLog4j2_2134Test {
 
     @Test