yvasyliev opened a new issue, #1386:
URL: https://github.com/apache/logging-log4j2/issues/1386
## Description
It is not possible to use custom logger appender without explicitly
specifying appender's package in `log4j2.xml`.
## Configuration
**Version:** `2.20.0`
**Operating system:** `Windows 10`, `Ubuntu 20.04.5 LTS`
**JDK:** `openjdk 17.0.6 2023-01-17 LTS`
## Logs
```
WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will
impact performance.
ERROR StatusConsoleListener Appenders contains an invalid element or
attribute "MyAppender"
ERROR StatusConsoleListener Unable to locate appender "myAppender" for
logger config "root"
```
## Reproduction
<table>
<tr><th>Project structure</th></tr>
<tr><td>
```
๐log4j2-demo
โ ๐pom.xml
โโโโ๐src
โ๐main
โ๐java
โ โ๐demo
โ โ๐log4j2
โ โ๐MyAppender.java
โ๐resources
โ๐log4j2.xml
```
</td></tr>
</table>
<table>
<tr><th>
๐`pom.xml`
</th></tr>
<tr><td>
```xml
<?xml version="1.0" encoding="UTF-8"?>
<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>
<groupId>demo.log4j2</groupId>
<artifactId>log4j2-demo</artifactId>
<version>1.0.0</version>
<properties>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.5.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>demo.log4j2.MyAppender</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>2.0.7</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j2-impl</artifactId>
<version>2.20.0</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.20.0</version>
</dependency>
</dependencies>
</project>
```
</td></tr>
</table>
<table>
<tr><th>
๐`MyAppender.java`
</th></tr>
<tr><td>
```java
package demo.log4j2;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
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.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.Serializable;
@Plugin(name = "MyAppender", category = Core.CATEGORY_NAME, elementType =
Appender.ELEMENT_TYPE)
public class MyAppender extends AbstractAppender {
private static final Logger LOGGER =
LoggerFactory.getLogger(MyAppender.class);
protected MyAppender(String name, Filter filter, Layout<? extends
Serializable> layout, boolean ignoreExceptions, Property[] properties) {
super(name, filter, layout, ignoreExceptions, properties);
}
@PluginFactory
public static MyAppender createAppender(@PluginAttribute("name") String
name, @PluginElement("Filter") Filter filter) {
return new MyAppender(name, filter,
PatternLayout.createDefaultLayout(), true, Property.EMPTY_ARRAY);
}
public static void main(String[] args) {
LOGGER.info("Hello world!");
}
@Override
public void append(LogEvent event) {
System.out.println(event.getMessage().getFormattedMessage());
}
}
```
</td></tr>
</table>
<table>
<tr><th>
๐`log4j2.xml`
</th></tr>
<tr><td>
```xml
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn">
<Appenders>
<MyAppender name="myAppender"/>
</Appenders>
<Loggers>
<Root level="ALL">
<AppenderRef ref="myAppender"/>
</Root>
</Loggers>
</Configuration>
```
</td></tr>
</table>
---
1. If I run this code in Intellij Idea, I will get the next output:
```shell
C:\Users\Yevhen\.jdks\corretto-17.0.6\bin\java.exe
"-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition
2020.2.2\lib\idea_rt.jar=50945:C:\Program Files\JetBrains\IntelliJ IDEA
Community Edition 2020.2.2\bin" -Dfile.encoding=UTF-8 -classpath
C:\Users\Yevhen\IdeaProjects\log4j2-demo\target\classes;C:\Users\Yevhen\.m2\repository\org\slf4j\slf4j-api\2.0.7\slf4j-api-2.0.7.jar;C:\Users\Yevhen\.m2\repository\org\apache\logging\log4j\log4j-slf4j2-impl\2.20.0\log4j-slf4j2-impl-2.20.0.jar;C:\Users\Yevhen\.m2\repository\org\apache\logging\log4j\log4j-api\2.20.0\log4j-api-2.20.0.jar;C:\Users\Yevhen\.m2\repository\org\apache\logging\log4j\log4j-core\2.20.0\log4j-core-2.20.0.jar
demo.log4j2.MyAppender
Hello world!
Process finished with exit code 0
```
2. If I build the project, run the jar:
```shell
mvn clean package
```
and run the jar, I will get the next output:
```shell
C:\Users\Yevhen\IdeaProjects\log4j2-demo\target>java -jar
log4j2-demo-1.0.0-jar-with-dependencies.jar
WARNING: sun.reflect.Reflection.getCallerClass is not supported. This
will impact performance.
ERROR StatusConsoleListener Appenders contains an invalid element or
attribute "MyAppender"
ERROR StatusConsoleListener Unable to locate appender "myAppender" for
logger config "root"
```
3. If I open ๐`log4j2.xml` and replace:
```xml
<Configuration status="warn">
```
with:
```xml
<Configuration status="warn" packages="demo.log4j2">
```
re-build the jar and run it, I will get the next output:
```shell
C:\Users\Yevhen\IdeaProjects\log4j2-demo\target>java -jar
log4j2-demo-1.0.0-jar-with-dependencies.jar
WARNING: sun.reflect.Reflection.getCallerClass is not supported. This
will impact performance.
WARN StatusConsoleListener The use of package scanning to locate plugins
is deprecated and will be removed in a future release
WARN StatusConsoleListener The use of package scanning to locate plugins
is deprecated and will be removed in a future release
WARN StatusConsoleListener The use of package scanning to locate plugins
is deprecated and will be removed in a future release
Hello world!
```
---
According to
[this](https://logging.apache.org/log4j/2.x/manual/plugins.html) article
`MyAppender` must be autoconfigured at build time:
> Serialized plugin listing files are generated by an annotation processor
contained in the log4j-core artifact which
> will automatically scan your code for Log4j 2 plugins and output a
metadata file in your processed classes. There is
> nothing extra that needs to be done to enable this; the Java compiler will
automatically pick up the annotation
> processor on the class path unless you explicitly disable it.
Even if I add this plugin to `pom.xml`, nothing will be changed:
```xml
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<executions>
<execution>
<id>log4j-plugin-processor</id>
<goals>
<goal>compile</goal>
</goals>
<phase>process-classes</phase>
<configuration>
<proc>only</proc>
<annotationProcessors>
<annotationProcessor>org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor
</annotationProcessor>
</annotationProcessors>
</configuration>
</execution>
</executions>
</plugin>
```
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