log4js.configure({
            appenders: {
                logs: {
                    type: 'file',
                    filename: '/tmp/ucp-index.log',
                },
            },
            categories: {
                index: { appenders: ['logs'], level: 'debug' },
                default: { appenders: ['logs'], level: 'debug' },
            },
        });
        logger = log4js.getLogger('index');

Error: EEXIST: file already exists, mkdir '/tmp'
    at Object.fs.mkdirSync (fs.js:872:3)
    at Object.module.exports.makeDirSync (sys/node_modules/streamroller/node_modules/fs-extra/lib/mkdirs/make-dir.js:23:13)
    at RollingFileStream._renewWriteStream (sys/node_modules/streamroller/lib/RollingFileWriteStream.js:241:8)
    at new RollingFileWriteStream (sys/node_modules/streamroller/lib/RollingFileWriteStream.js:76:10)
    at new RollingFileStream (sys/node_modules/streamroller/lib/RollingFileStream.js:18:5)
    at openTheStream (sys/node_modules/log4js/lib/appenders/file.js:17:18)
    at fileAppender (sys/node_modules/log4js/lib/appenders/file.js:59:16)
    at Object.configure (sys/node_modules/log4js/lib/appenders/file.js:117:10)
    at clustering.onlyOnMaster (sys/node_modules/log4js/lib/appenders/index.js:89:27)
    at Object.onlyOnMaster (sys/node_modules/log4js/lib/clustering.js:85:50)