Developing and Conventions Logging

Logging

Besu employs the logging facade SLF4J, using Apache Log4j 2.x as its backend. Accordingly, levels of detail can be specified as follows:

• OFF: The highest possible rank and is intended to turn off logging.
• ERROR: Designates error events that might still allow the application to continue running.
• WARN: Designates potentially harmful situations.
• INFO: Designates informational messages that highlight the progress of the application at coarse-grained level.
• DEBUG: Designates fine-grained informational events that are most useful to debug an application.
• TRACE: Designates finer-grained informational events than the DEBUG.
• ALL: All levels including custom levels.

Use log levels consistently and keep operational logs actionable for node operators.

For modifying the log output of a running client, use a custom log4j config file by setting a system property at startup. Besu's logging doc provides documentation on configuring logging in Besu.