log4js-config.json

{
    "appenders": {
        "console": {
            "type": "stdout"
        },
        "app": {
            "type": "file",
            "filename": "log/app.log",
            "maxLogSize": 1048576,
            "numBackups": 10
        },
        "errorFile": {
            "type": "file",
            "filename": "log/errors.log",
            "maxLogSize": 1048576,
            "numBackups": 10
        },
        "errors": {
            "type": "logLevelFilter",
            "level": "ERROR",
            "appender": "errorFile"
        }
    },
    "categories": {
        "default": {
            "appenders": [
                "console",
                "app",
                "errors"
            ],
            "level": "TRACE"
        }
    }
}