Setting and Clearing Log Levels Using the Storm UI

To set log level from the Storm UI:

Click on a running topology.
Click on “Change Log Level” in the Topology Actions section:
For an existing logger, select the desired log level for the logger. Alternately, add a logger and set the desired log level.
Optionally, specify a timeout value in seconds, after which changes will be reverted automatically. Specify 0 if no timeout is needed.
Click "Apply".

The preceding example sets the log4j log level to ERROR for the root logger, and to DEBUG for storm.starter. Logging for the root logger will be limited to error events, and finer-grained informational events (useful for debugging the application) will be recorded for storm.starter packages.

To clear (reset) a log level setting using the Storm UI, click on the “Clear” button. This reverts the log level back to what it was before you added the setting. The log level line will disappear from the UI.