Updated 2020-02-13
Logging
Hyperledger Besu uses Log4J2 for logging. There are two methods to configure logging behavior:
The Besu Sample Networks provides an example implementation using Elastic Stack (also known as ELK) for log management.
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.
For most use-cases, the basic method provides sufficient configurability.
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.
<?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
Log rotation
The Besu Sample Networks logging configuration defines a log rotation to restrict the size of the log files.