Updated 2019-12-17

Logging

Hyperledger Besu uses Log4J2 for logging. There are two methods to configure logging behavior:

Basic - changes the log level.
Advanced - configures the output and format of the logs.

Note

For most use-cases, the basic method provides sufficient configurability.

Basic Log Level Setting

Use the --logging command line option to specify the logging verbosity. The --logging option changes the volume of events displayed in the log. Valid log levels are OFF, FATAL, ERROR, WARN, INFO, DEBUG, TRACE, ALL. The default level is INFO.

Tip

Use the admin_changeLogLevel API method to change the log level while Besu is running.

Advanced Custom Logging

You can provide your own logging configuration using the standard Log4J2 configuration mechanisms. For example, the following Log4J2 configuration is the same as the default configuration except logging of stack traces for exceptions is excluded.

debug.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="INFO">
  <Properties>
    <Property name="root.log.level">INFO</Property>
  </Properties>

  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSSZZZ} | %t | %-5level | %c{1} | %msg %throwable{short.message}%n" />
    </Console>
  </Appenders>
  <Loggers>
    <Root level="${sys:root.log.level}">
      <AppenderRef ref="Console" />
    </Root>
  </Loggers>
</Configuration>

To use your custom configuration, set the environment variable LOG4J_CONFIGURATION_FILE to the location of your configuration file.

If you have more specific requirements, you can create your own log4j2 configuration.

For Bash-based executions, you can set the variable for only the scope of the program execution by setting it before starting Besu.

Example

To set the debug logging and start Besu connected to the Rinkeby testnet:

LOG4J_CONFIGURATION_FILE=./debug.xml besu --network=rinkeby

Source

log4j2.xml