Log4j.properties in Spring boot

If you want spring boot to use log4j instead of its own default logging (logback) then you have to exclude default logging and include the log4j dependency for spring boot in your pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j</artifactId>
</dependency>   

that way is going to look for your log4j.properties file located in src/main/resources.

Also if you wish to use properties defined in you application.properties inside the log4j.properties file

for example, you want to have log.file.path defined in your application.properties and use it on log4j.properties

Then you have to define filtering inside your pom.xml:

<filters>
    <filter>src/main/resources/application.properties</filter>
</filters>
<resources>
    <resource>
        <directory>src/main/resources</directory>
        <includes>
            <include>log4j.properties</include>
        </includes>         
        <filtering>true</filtering>
    </resource>
</resources>

That way you can have:

log4j.appender.file.File=${log.file.path}/${project.artifactId}.log

in your log4j.properties file