I’m trying to add Logback on a Vertx project, but it seems SLF4J can’t see logback even if itself come from a logback dependency. I used maven dependency logback-classic, which transitively imports slf4j-api and logback-core.

When I run a simple main class with random log I have the following error:

SLF4J: No SLF4J providers were found.
SLF4J: Defaulting to no-operation (NOP) logger implementation 
SLF4J: See https://www.slf4j.org/codes.html#noProviders for further details.

My pom.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>com.example</groupId>
  <artifactId>vertx-stock-broker</artifactId>
  <version>1.0.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
    <maven-shade-plugin.version>3.2.4</maven-shade-plugin.version>
    <maven-surefire-plugin.version>2.22.2</maven-surefire-plugin.version>
    <exec-maven-plugin.version>3.0.0</exec-maven-plugin.version>

    <vertx.version>4.5.11</vertx.version>
    <logback-classic.version>1.5.12</logback-classic.version>
    <junit-jupiter.version>5.9.1</junit-jupiter.version>

    <main.verticle>com.example.vertx_stock_broker.MainVerticle</main.verticle>
    <launcher.class>io.vertx.core.Launcher</launcher.class>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.vertx</groupId>
        <artifactId>vertx-stack-depchain</artifactId>
        <version>${vertx.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-web</artifactId>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>${logback-classic.version}</version>
    </dependency>

    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-junit5</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <version>${junit-jupiter.version}</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-engine</artifactId>
      <version>${junit-jupiter.version}</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${maven-compiler-plugin.version}</version>
        <configuration>
          <release>17</release>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-shade-plugin</artifactId>
        <version>${maven-shade-plugin.version}</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <transformers>
                <transformer
                  implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                  <manifestEntries>
                    <Main-Class>${launcher.class}</Main-Class>
                    <Main-Verticle>${main.verticle}</Main-Verticle>
                  </manifestEntries>
                </transformer>
                <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
              </transformers>
              <outputFile>${project.build.directory}/${project.artifactId}-${project.version}-fat.jar
              </outputFile>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>${maven-surefire-plugin.version}</version>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>${exec-maven-plugin.version}</version>
        <configuration>
          <mainClass>${launcher.class}</mainClass>
          <arguments>
            <argument>run</argument>
            <argument>${main.verticle}</argument>
          </arguments>
        </configuration>
      </plugin>
    </plugins>
  </build>


</project>

The running class:

package com.example.vertx_stock_broker;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Test {
  private static final Logger LOG = LoggerFactory.getLogger(Test.class);

  public static void main(String[] args) {
    LOG.debug("debug");
    LOG.info("info");
    LOG.error("error");
  }
}

I run it with the IntelliJ run tool which silently run (I have shorten paths with ‘…’):

openjdk-22.0.2binjava.exe "-javaagent:...IntelliJ IDEA 2024.2.3libidea_rt.jar=64366:...IntelliJ IDEA 2024.2.3bin" 
-Dfile.encoding=UTF-8 
-Dsun.stdout.encoding=UTF-8 
-Dsun.stderr.encoding=UTF-8 
-classpath ...vertx-stock-brokertargetclasses;
    ....m2repositoryiovertxvertx-web4.5.11vertx-web-4.5.11.jar;
    ....m2repositoryiovertxvertx-web-common4.5.11vertx-web-common-4.5.11.jar;
    ....m2repositoryiovertxvertx-auth-common4.5.11vertx-auth-common-4.5.11.jar;
    ....m2repositoryiovertxvertx-bridge-common4.5.11vertx-bridge-common-4.5.11.jar;
    ....m2repositoryiovertxvertx-core4.5.11vertx-core-4.5.11.jar;
    ....m2repositoryionettynetty-common4.1.115.Finalnetty-common-4.1.115.Final.jar;
    ....m2repositoryionettynetty-buffer4.1.115.Finalnetty-buffer-4.1.115.Final.jar;
    ....m2repositoryionettynetty-transport4.1.115.Finalnetty-transport-4.1.115.Final.jar;
    ....m2repositoryionettynetty-handler4.1.115.Finalnetty-handler-4.1.115.Final.jar;
    ....m2repositoryionettynetty-transport-native-unix-common4.1.115.Finalnetty-transport-native-unix-common-4.1.115.Final.jar;
    ....m2repositoryionettynetty-codec4.1.115.Finalnetty-codec-4.1.115.Final.jar;
    ....m2repositoryionettynetty-handler-proxy4.1.115.Finalnetty-handler-proxy-4.1.115.Final.jar;
    ....m2repositoryionettynetty-codec-socks4.1.115.Finalnetty-codec-socks-4.1.115.Final.jar;
    ....m2repositoryionettynetty-codec-http4.1.115.Finalnetty-codec-http-4.1.115.Final.jar;
    ....m2repositoryionettynetty-codec-http24.1.115.Finalnetty-codec-http2-4.1.115.Final.jar;
    ....m2repositoryionettynetty-resolver4.1.115.Finalnetty-resolver-4.1.115.Final.jar;
    ....m2repositoryionettynetty-resolver-dns4.1.115.Finalnetty-resolver-dns-4.1.115.Final.jar;
    ....m2repositoryionettynetty-codec-dns4.1.115.Finalnetty-codec-dns-4.1.115.Final.jar;
    ....m2repositorycomfasterxmljacksoncorejackson-core2.16.1jackson-core-2.16.1.jar;
    ....m2repositorychqoslogbacklogback-core1.5.12logback-core-1.5.12.jar;
    ....m2repositoryorgslf4jslf4j-api2.0.7slf4j-api-2.0.7.jar com.example.vertx_stock_broker.MainVerticle

My logback.xml file:

<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>

  <root level="debug">
    <appender-ref ref="STDOUT" />
  </root>
</configuration>

I didn’t find any dependencies conflict or duplication. OpenJdk22 is used.

I expect to get logback logs at runtime

Edit:

Thanks to @Ceki answer, it appear that the problem was with IntelliJ, the logback-classic jar was not provided in the classpath generated run command, after an IntelliJ cache clean and a restart the problem was solved. Now logback-classic is provided in classpath and it work as expected.