Logging Library Location and Use

Owned by Prudence Au
Oct 14, 2019
1 min read

see https://git.onap.org/logging-analytics/tree/reference/logging-slf4j

and usage ONAP Development#DeveloperUseoftheLoggingLibrary  ONAP Development#KubernetesDevOps and Logging User Guide#LoggingDevOps

see Spring AOP example (minimal changes to existing code base) WIP in LOG-135: Logging RI: Code example microservice war with a minimal REST API using the logging libraryClosed documented at ONAP Development#LoggingWithAOP

EELF

EELF is the Event and Error Logging Framework, described at https://github.com/att/EELF.

EELF abstracts your choice of logging provider, and decorates the familiar Logger contracts with features like:

  • Localization. 

  • Error codes. 

  • Generated wiki documentation.

  • Separate audit, metrics, security error and debug logs. 

EELF is a facade, so logging output is configured in two ways:

  1. By selection of a logging provider such as Logback or Log4j, typically via the classpath. 

  2. By way of a provider configuration document, typically logback.xml or log4j.xml. See Providers.

SLF4J

SLF4J is a logging facade, and a humble masterpiece. It combines what's common to all major, modern Java logging providers into a single interface. This decouples the caller from the provider, and encourages the use of what's universal, familiar and proven. 

EELF also logs via SLF4J's abstractions as the default provider.

Providers

Logging providers are normally enabled by their presence in the classpath. This means the decision may have been made for you, in some cases implicitly by dependencies. If you have a strong preference then you can change providers, but since the implementation is typically abstracted behind EELF or SLF4J, it may not be worth the effort.

Logback

Logback is the most commonly used provider. It is generally configured by an XML document named logback.xml. See Configuration.

See HELM template https://git.onap.org/logging-analytics/tree/reference/provider/helm/logback

Log4j 2.X

Log4j 2.X is somewhat less common than Logback, but equivalent. It is generally configured by an XML document named log4j.xml. See Configuration.