Logging

1. Log4j2

Configuring log outputs in OpenEMS with fine granularity is often useful for debugging purposes. Setting the ROOT log level to DEBUG or TRACE may flood the console output, making it difficult to debug specific packages. OpenEMS utilizes the Log4j2 framework for logging. To customize log output using a log4j2.xml file, follow these steps:

1.1. Create config file

Create a new file log4j2.xml in any location of your choice. As a example, this config represents the default OpenEMS log configuration:

<Configuration>
    <Appenders>
        <!-- Console Appender -->
        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{ISO8601} [%-8.8t] %-5p [%-30.30c] %m%n" />
        </Console>

        <!-- PaxOsgi Appender -->
        <PaxOsgi name="paxosgi" />
    </Appenders>

    <Loggers>
        <!-- OpenEMS Logger -->
        <Logger name="io.openems" level="info" additivity="false">
            <AppenderRef ref="console" />
        </Logger>

        <!-- Root Logger -->
        <Root level="info">
            <AppenderRef ref="console" />
            <AppenderRef ref="paxosgi" />
        </Root>
    </Loggers>
</Configuration>

for more information, about the log4j2 configuration, see the official documentation: https://logging.apache.org/log4j/2.x/manual/configuration.html

1.2. Update OpenEMS configuration

To tell OpenEMS to use this configuration file, change the logging config using Apache Felix. Open the Apache Felix Web Console in your browser (e.g. http://localhost:8080/system/console/configMgr) and search for the org.ops4j.pax.logging configuration. Change the org.ops4j.pax.logging.log4j2.config.file value to the path of your log4j2.xml file.