SLF4J

Cheatsheet

Multiple bindings were found on the class path (opens in a new tab)

Logback - Turn on debug flag

# System Property
-Dlogback.debug=true
# This will print out internal status messages of logback

MDC

• Store contextual information on a per-thread basis, such as a transaction ID.

Modules

jul-to-slf4j

slf4j-jdk-platform-logging

Logback

Logback - Config

• By default, additivity="true" which sends logging output to any appender attached higher in the hierarchy.

  Try setting additivity="false" if duplicate logging output happens.

• Logback - Chapter 3 Configuration - Overriding the default cumulative behaviour (opens in a new tab)

Logback - Appenders

• immediateFlush

  By default, each log event is immediately flushed to the underlying output stream. This default approach is safer in the sense that logging events are not lost in case your application exits without properly closing appenders.

  Try using immediateFlush = true if logging events are lost in logs.

RollingFileAppender

• RollingPolicy

  • How to roll over log files

• TriggeringPolicy

  • When to roll over log files

Logback - Layout

PatternLayout

• Colored output

  • Jansi library is required for ANSI color code interpretation on Windows.
  • POSIX systems support ANSI color code interpretation natively.

• Logback - Chapter 6 Layouts - PatternLayout (opens in a new tab)

  Reference for conversion patterns

Logback - Integration

Spring Boot

• Spring Boot by default uses programmatic configuration to improve startup time, with Spring config for customizations.

  Logback default config class: org.springframework.boot.logging.logback.DefaultLogbackConfiguration

Spring default config

org.springframework.boot.logging.logback