Spring Boot Logging Framework

Project Objective

• Spring Boot being highly opinionated framework , it has it's own mindset.
• It allows us to forget about the majority of the configuration settings, many of which it auto-configures.
• It understands the need of logging , in a typical web application|web service

Logging Dependencies

• In the case of logging, we don't have to explicitly import it's starter , since a starter, like our spring-boot-starter-web, depends on spring-boot-starter-logging, which automatically pulls in JCL (Jakarta Commons Logging API)

Simple Logging Framework (Facade) in Java

• Simple Logging framework(facade) in Java : SLF4J

Logging Levels

• There are different logging levels , in asc order of severity
  • trace , debug , info , warn , error
• Default logging level in spring boot app : info
• Meaning : spring boot app will auto display : info , warn , error

Adding Logging in Controller/Service Classes

• Add one field :
  • org.slf4j.Logger logger = LoggerFactory.getLogger(NameOfClass.class);
• OR simply use Lombok annotation
  • @Slf4j : at the class level -- It will auto inject a Logger in the field : "log"

Example

@RestController
@Slf4j
public class LoggingController {

    @RequestMapping("/")
    public String index() {
        //it's in asc manner of severity : logging levels
        log.trace("A TRACE Message");
        log.debug("A DEBUG Message");
        log.info("An INFO Message");
        log.warn("A WARN Message");
        log.error("An ERROR Message");

        return "Testing logging here....";
    }
}

Configuration in application.properties

• Note:
  • Default setting in application.properties file :
    • logging.level.root=info
  • To change it to error (in deployment phase)
    • logging.level.root=error
  • To enable logging of debugging message , for a particular module/package :
    • eg : debug=true
    • logging.level.org.springframework.security=trace
    • logging.level.com.blogs.service=debug
  • After complete testing of the project, to suppress , info , debug messages , set :
    • logging.level.root=error