The helper libraries provide several ways to produce log output in openHAB. This can be useful for providing information or error messages from your scripts to help diagnose issues. In some of the following examples, the logger can be modified to wherever you want the log to go. The default logger used in the modules and scripts is ‘jsr223.<language name>’, which is pulled from the value assigned to the LOG_PREFIX variable in the configuration library. If this is modified, be sure to configure your logging to include the logger chosen.

Rule Decorator

The rule decorator adds a logger attribute to the function or class that it is decorating.

@rule("Example Rule")
@when("System started")
def example_function(event):
    example_function.log.info("Example info log")
    example_function.log.warn("Example warning log")
    example_function.log.error("Example error log")
    example_function.log.debug("Example debug log")
    example_function.log.critical("Example trace log")

Decorators have not been created for the JavaScript helper libraries.

Decorators have not been created for the Groovy helper libraries.


It is also possible to create a logger using the core.log library to be used by all functions in a script or library.

from core.log import logging, LOG_PREFIX

logging.debug("Logging example from root logger [DEBUG]: [{}]".format(5 + 5))
logging.info("Logging example from root logger [INFO]: [{}]".format(5 + 5))
logging.warning("Logging example from root logger [WARN]: [{}]".format(5 + 5))
logging.error("Logging example from root logger [ERROR]: [{}]".format(5 + 5))
logging.critical("Logging example from root logger [TRACE]: [{}]".format(5 + 5))

logging.getLogger("{}.test_logging_script".format(LOG_PREFIX)).info("Logging example from logger, using text appended to LOG_PREFIX: [{}]".format(5 + 5))

log = logging.getLogger("{}.test_logging_script".format(LOG_PREFIX))
log.info("Logging example from logger, using text appended to LOG_PREFIX: [{}]".format(5 + 5))

The core.log library does not exist for this language.

The core.log library does not exist for this language.


The openHAB LogAction, as used in the Rules DSL, can be imported and used to write to the logs from a script or rule. Since LogAction uses SLF4J, it supports parameterized logging. Parameterized logging is beneficial, since the values in the parameters are not processed unless the logger is visible in the current logging level. This means that the complicated logging you do in debug does not affect the performance of your system when the logging level is set to info.

from core.actions import LogAction

LogAction.logInfo("EXAMPLE", "Example info log [{}]", 5 + 5)
LogAction.logWarn("EXAMPLE", "Example warning log [{}]", 5 + 5)
LogAction.logError("EXAMPLE", "Example error log [{}]", 5 + 5)
LogAction.logDebug("EXAMPLE", "Example debug log [{}]", 5 + 5)
var OPENHAB_CONF = Java.type("java.lang.System").getenv("OPENHAB_CONF");
load(OPENHAB_CONF + '/automation/lib/javascript/core/actions.js');

LogAction.logInfo("EXAMPLE", "Example info log [{}]", 5 + 5);
LogAction.logWarn("EXAMPLE", "Example warning log [{}]", 5 + 5);
LogAction.logError("EXAMPLE", "Example error log [{}]", 5 + 5);
LogAction.logDebug("EXAMPLE", "Example debug log [{}]", 5 + 5);
import org.eclipse.smarthome.model.script.actions.LogAction

def logInfo = LogAction.&logInfo

logInfo("Rules", "This is a test [{}]", 5 + 5)
logInfo("EXAMPLE", "Example info log [{}]", 5 + 5)
logWarn("EXAMPLE", "Example warning log [{}]", 5 + 5)
logError("EXAMPLE", "Example error log [{}]", 5 + 5)
logDebug("EXAMPLE", "Example debug log [{}]", 5 + 5)


As an alternative to using core.log, you can access SLF4J directly in a similar manner. SLF4J supports parameterized logging.

from org.slf4j import LoggerFactory
from configuration import LOG_PREFIX
log = LoggerFactory.getLogger("{}.EXAMPLE".format(LOG_PREFIX))

log.info("Example info log [{}]", 5 + 5)
log.warn("Example warning log [{}]", 5 + 5)
log.error("Example error log [{}]", 5 + 5)
log.debug("Example debug log [{}]", 5 + 5)

var LoggerFactory = Java.type(‘org.slf4j.LoggerFactory’); var log = LoggerFactory.getLogger(“jsr223.javascript.EXAMPLE”);

log.info(“Example info log [{}]”, 5 + 5); log.warn(“Example warning log [{}]”, 5 + 5); log.error(“Example error log [{}]”, 5 + 5); log.debug(“Example debug log [{}]”, 5 + 5);

Documentation has not yet been created for this functionality.