How can I change the default location of log4j2.xml in Java Spring Boot?

As mentioned in the log4j2 documentation here, you can include a file named log4j2.component.properties in your resources folder (or anywhere in the classpath) and inside that file, you can provide the name of the file location (or a new file name) like this:

log4j.configurationFile=path/to/log4j2.xml

or

log4j.configurationFile=classpath:log4j2-custom.xml (if the file is on the classpath)

You can alternatively provide the config file location via the context-param fields of web.xml as mentioned here, but I haven't tried that option

(This works with Spring Boot too)

The answer of micpalmia is absolutely correct.

I needed to put the configuration outside the classpath I didn't want to pass the config file as a parameter. So i put a very simple logging configuration in the classpath resources and had the spring boot application reconfigure logging upon start, like so:

@SpringBootApplication
public class Application implements CommandLineRunner {
    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }

    @Override
    public void run(String... param) throws UnsupportedEncodingException {
        Configurator.initialize(null, "config/log4j2.xml");
        // ...
    }
}

This approach has a significant disadvantage: The whole application boot process will not be logged as externally configured. But once the custom code is run the logger works as intended. While you may not, I find this to be a compromise I can live with.

I have the same problem in my project, besides log4j2.xml I also need other config files in the class path. Here is my 2 solutions that works:

Soluation 1 : Start spring boot application with org.springframework.boot.loader.JarLauncher

java -classpath SpringBootProject.jar;./config org.springframework.boot.loader.JarLauncher

Solution 2: Write a './config' class path entry in the MANIFEST.MF in the jar

    <build>
    <plugins>
      <plugin>
        <artifactId>maven-jar-plugin</artifactId>
        <configuration>
          <archive>
            <manifestEntries>
               <Class-Path>./config/</Class-Path>
            </manifestEntries>
          </archive>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>1.5.3.RELEASE</version>
        <executions>
          <execution>
            <goals>
              <goal>repackage</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

In case of property file:

java -Dlog4j.configuration=file:/path/to/log4j.properties -jar app.jar

To the command line works in Spring Boot 2. Don't forget to add file: before the path.

Another way to do this in Spring boot

 java -jar app.jar --logging.config=/path/to/log4j2.xml

I have working solution to set custom path or change existing file path for logging file. If you have configured log4j2.xml file, open it and see where you have to do one line change to config log file path.

If you try to rename the log4j2.xml file other than the default name. In order to load the file. For a spring boot application in application.properties file add below property this would work

logging.config=classpath:logfilename.xml

After a lot of struggle I found that the only thing that works in all cases (independent of used builder, also with .jar however it is started) is to set log4j.configurationFile system variable programmatically to load from start folder (instead of classpath / .jar resource).

In start class use private static Logger log; instead of private static final Logger log = LogManager.getLogger(<class>.class); used in other classes.

In start class do not initialise calls variables at declaration but do that in the main method after log initialization (otherwise you might miss logs).

First thing in main(String[] args) is to set log4j.configurationFile and initialise log after that:

System.getProperties().setProperty("log4j.configurationFile", "log4j2.xml");
log = LogManager.getLogger(TSVConverter.class);