Logging

Logging is a necessity in almost any application. SeedStack standardize logging through the popular SLF4J logging facade but the actual implementation is chosen at the project level.

Recommended implementation #

SeedStack is compatible with any SLF4J implementation but we recommend Logback as an efficient, natural fit for SLF4J. To add Logback to your project, use the following dependency snippet:

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.5.5</version>
</dependency>

dependencies {
    compile("ch.qos.logback:logback-classic:1.5.5")
}

Usage #

You can inject a logger in any class by annotating an SLF4J logger field with @Logging:

public class SomeClass {
    @Logging
    private Logger logger;
}

This will automatically inject a logger for the enclosing class. This also works on static fields but if you want your logger fields to be final, you must use the traditional SLF4J syntax instead:

public class SomeClass {
    private static final Logger LOGGER = LoggerFactory.getLogger(SomeClass.class);
}

Configuration #

SeedStack supports any SLF4J implementation but can automatically configure Logback. If you want to use another implementation you have to use its native configuration mechanism.

Automatic configuration #

A default configuration mechanism is provided. If you don’t specify any configuration, it will be auto-configured to the following settings:

• A root logger level set to INFO,
• A console appender outputting to System.out (standard output),
• A color output (only if supported by the environment),
• The following pattern for the console appender:

%highlight(%-5level) [%d{ISO8601}] %magenta(%-8thread) %cyan(%-30logger{30}) %msg%n%red(%throwable)

For supported SLF4J implementations (currently only Logback), you can easily change the logging system configuration with the following options:

logging:
  # Logging level of the root logger
  level: (ERROR|WARN|INFO|DEBUG|TRACE)
  
  # The pattern for the default console appender
  pattern: (String)
  
  # Configured loggers with the name of logger as key
  loggers:
    org.seedstack.samples.logging.SampleLogger:
      # Logging level for this specific logger
      level: (ERROR|WARN|INFO|DEBUG|TRACE)     
      
      # Additivity for this specific logger
      additive: (boolean)  

mvn -q -Dargs="logging" seedstack:config

Native configuration #

For advanced needs, you can still use the native configuration mechanism of the chosen SLF4J implementation. In this case, it will completely override any automatic configuration.