I am trying to leverage log4j2 within my spring-boot app. Long term the goal is to leverage some of the DB appenders that log4j2 supports, but initially just trying to make sure it’s loading log4j instead of logback.

I have my log4j2.xml file located in my src/main/resources folder.

Im using gradle for my build and have the following config

implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'com.fasterxml.jackson.core:jackson-databind'
    implementation 'com.fasterxml.jackson.dataformat:jackson-dataformat-yaml'
    implementation 'org.postgresql:postgresql'
    implementation 'org.springframework.data:spring-data-mongodb:4.4.0'
    implementation 'org.springframework.data:spring-data-commons:3.4.0'
    implementation 'org.springframework.boot:spring-boot-starter-actuator:3.4.0'
    implementation 'org.mongodb:mongodb-driver-sync:5.2.1'
    implementation 'org.mongodb:mongodb-driver-core:5.2.1'
    implementation 'com.google.code.gson:gson:2.11.0'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation "me.paulschwarz:spring-dotenv:4.0.0"
    implementation 'org.apache.logging.log4j:log4j-mongodb:2.24.3'
    implementation "org.springframework.boot:spring-boot-starter-log4j2:3.4.0"
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'

    modules {
        module("org.springframework.boot:spring-boot-starter-logging") {
            replacedBy("org.springframework.boot:spring-boot-starter-log4j2", "Use Log4j2 instead of Logback")
        }
    }

The modules component at the bottom seems to be correctly replacing all instances of spring-boot-start-logging with spring-boot-starter-log4j2. I was able to verify that with the output of the ./gradlew dependencies which produced this output for every line that had spring-boot-starter-logging.

|    |    |    +--- org.springframework.boot:spring-boot-starter-logging:3.3.5 -> org.springframework.boot:spring-boot-starter-log4j2:3.4.0
|    |    |    |    +--- org.apache.logging.log4j:log4j-slf4j2-impl:2.24.1 -> 2.23.1
|    |    |    |    |    +--- org.apache.logging.log4j:log4j-api:2.23.1
|    |    |    |    |    +--- org.slf4j:slf4j-api:2.0.9 -> 2.0.16
|    |    |    |    |    --- org.apache.logging.log4j:log4j-core:2.23.1
|    |    |    |    |         --- org.apache.logging.log4j:log4j-api:2.23.1
|    |    |    |    +--- org.apache.logging.log4j:log4j-core:2.24.1 -> 2.23.1 (*)
|    |    |    |    --- org.apache.logging.log4j:log4j-jul:2.24.1 -> 2.23.1
|    |    |    |         --- org.apache.logging.log4j:log4j-api:2.23.1

I also verified that I don’t have any instances of slf4j implementations other than the one shown above from log4j2.

When I run the app, the log4j2.xml file is completely ignored. I know this because it references an invalid path for where to put the FileAppender output that shoudl throw an error (this was done on purpose to make testing easier).

If I try to force the loading of the file by setting

logging:
   config: classpath:log4j2.xml

in my application.yml file, I just get a new block at the top of my console on execution complaining about logback-classic and then I get the SPRING ANSI art and that’s it. No other calls to the Log4j impl actually come through and no files are ever created.

I feel like there has to be something simple I am missing as all of the articles I can find seem to imply that I have done all of the correct things to make this work, but I sure can’t find the issue.

I am expecting to get an error because log4j2.xml is attempting to write to a log file located at c:/temp which is an invalid path on my Mac.

I also attempted to try using the log4j2.yml file to see if that was working, and what I get when I do that via the

logger:
   config: classpath:log4j2.yml

entry is an error message stating that only XML formats are valid here.