A full express application that demonstrates how to configure log4js for the most common use-case.

To run:

npm install
npm start

Config file is in config/log4js.json. It defines three appenders that are children of the clustered appender. The clustered appender makes sure that only the master process writes to the log files, otherwise having multiple processes try to write at the same time will cause problems. Three log files are defined: log/app.log gets all the log messages and is configured to rotate when the file gets to 10Mb in size, keeping 3 backups of the file; log/errors.log uses the logLevelFilter to only get ERROR messages; log/access.log contains only the http request logs, using the connect-logger, and is configured to rotate every day.