Integrating SLF4J with Logback in Micronaut

Logging is a critical aspect of any application’s development and maintenance. It provides invaluable insights into the behavior of your software, helping you identify issues, track performance, and ensure everything is running smoothly. In the Micronaut framework, integrating logging is a breeze, thanks to its seamless support for the Simple Logging Facade for Java (SLF4J). Let’s look into how we can integrate logback in Micronaut

Understanding SLF4J

SLF4J is a widely-used logging framework in the Java ecosystem, known for its simplicity and flexibility. It serves as a facade for various logging frameworks like Logback, Log4j, and Java Util Logging (JUL), allowing developers to choose the underlying implementation that best suits their needs.

Why SLF4J in Micronaut?

Integrating SLF4J into your Micronaut application brings several benefits:

  1. Abstraction: SLF4J abstracts away the underlying logging implementation, making it easy to switch between different logging libraries without changing your code.
  2. Flexibility: You can choose the logging framework that aligns with your project requirements, whether it’s Logback for extensive customization or Log4j for legacy compatibility.
  3. Performance: SLF4J is designed for efficiency, minimizing the impact on your application’s performance, even when logging extensively.

Integration Steps

Now, let’s walk through the steps to integrate SLF4J into your Micronaut application:

Step 1: Add Dependencies

First, add the necessary dependencies to your build.gradle

dependencies {
    // Other dependencies

Step 2: Configure Logback

Create a logback.xml file in the resources directory of your Micronaut project. This file contains the configuration for Logback. Here’s a basic example:


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

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


Step 3: Creating Centralized Logger

package com.example.util

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

inline fun <reified T> T.logger(): Logger {
    if (T::class.isCompanion) {
        return LoggerFactory.getLogger(
    return LoggerFactory.getLogger(

Step 4: Logging

You can now use SLF4J in your Micronaut components, services, or controllers, just as shown in the below example:

class TestController {
    private val log = logger()
    suspend fun pathVariable(params: String?): String? {
        log.error("This is a test error")
        return params


Implementation: Code


Integrating Logback with SLF4J in your Micronaut application is a straightforward process that provides you with robust logging capabilities. You can customize your logging configuration in the logback.xml file to suit your specific needs. This combination of Micronaut, SLF4J, and Logback ensures that you have effective and flexible logging in your application for debugging and monitoring purposes.

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