Configuring Logback Logging in Spring Boot: XML, Properties, and Code Examples

Spring Boot uses Logback as its default logging framework; you can enable it directly when generating a project or add SLF4J and Logback dependencies manually:

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-api</artifactId>
  <version>1.7.21</version>
</dependency>

<dependency>
  <groupId>ch.qos.logback</groupId>
  <artifactId>logback-core</artifactId>
  <version>1.1.7</version>
</dependency>

<dependency>
  <groupId>ch.qos.logback</groupId>
  <artifactId>logback-classic</artifactId>
  <version>1.1.7</version>
</dependency>

SLF4J acts as a simple façade allowing you to switch the underlying logging implementation without changing your code. After adding the dependencies, you can log with LoggerFactory.getLogger(...) and logger.info(...).

Quick implementation steps :

Create logback.xml under src/main/resources with a console appender ( STDOUT) and a rolling file appender ( fileLog) that writes to ${logFile}.log and defines pattern, charset, and rolling policy.

In application.yml set logging.config: classpath:logback.xml to point Spring Boot to the configuration file.

Add logging code to a controller, e.g.:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    private final Logger logger = LoggerFactory.getLogger(TestController.class);

    @RequestMapping(value = "/test", method = RequestMethod.GET)
    public String logTest(String name, String age) {
        logger.info("logTest,name:{},age:{}", name, age);
        return "success";
    }
}

If Lombok is available, the controller can be simplified with @Slf4j:

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class TestController {
    @RequestMapping(value = "/test", method = RequestMethod.GET)
    public String logTest(String name, String age) {
        log.info("logTest,name:{},age:{}", name, age);
        return "success";
    }
}

When the application runs, logs appear on the console and are written to logs/mutest.log as configured.

Logback XML structure : <configuration> – root element with optional attributes scan, scanPeriod, debug. <property> – defines global variables such as logFile and maxFileSize. <appender> – defines how logs are output. Types include ConsoleAppender, FileAppender, and RollingFileAppender, each with its own sub‑elements ( file, append, encoder, rollingPolicy, filter, etc.). <logger> – optional logger for a specific package or class, specifying name, level, additivity, and one or more appender-ref entries. <root> – mandatory root logger that sets the default level and references the primary appenders.

Log levels are TRACE < DEBUG < INFO < WARN < ERROR. The root logger defaults to DEBUG if not set; you can override it in logback.xml or via application.yml using logging.level entries.

Rolling policies control log file rotation. Common policies are: TimeBasedRollingPolicy – rotates based on time (e.g., daily) and can keep a maxHistory of archived files. SizeBasedTriggeringPolicy – rotates when a file reaches a size limit (e.g., 30 MB). SizeAndTimeBasedRollingPolicy – combines both time and size criteria.

Each policy uses <fileNamePattern> to define the naming scheme, often including ${logFile}, a date pattern, and %i for index when multiple files are created on the same day.

Filters let you include or exclude events. Examples: LevelFilter – deny a specific level (e.g., WARN) while accepting others. ThresholdFilter – only allow events at or above a given level (e.g., INFO). EvaluatorFilter – uses a boolean expression (e.g., message.contains("success")) to decide acceptance.

Finally, integrate Logback with Spring Boot’s application.yml by specifying the config file and optional per‑package log levels, for example:

logging:
  config: classpath:logback.xml
  level:
    com.example.demo.dao: trace

This tutorial demonstrates a complete, production‑ready logging setup for a Spring Boot backend application.