Winston日志文件在应用重启时丢失

Question

I'm using Winston logger for node.js, and everytime I restart the app, the logs get overwritten by the blank ones, starting at the moment of the restart. I need to keep the logs, SPECIALLY when I have to restart the app, since it's surely due to an error. I've read the documentation at GitHub, but found nothing about this. This is how I'm using the transports:

winston.add(winston.transports.Console, {
    level: config.logLevel,
    silent: false,
    colorize: true, 
    timestamp: true
});
winston.add(winston.transports.File, {
    filename: config.logFile,
    maxsize: 524288000, // 500MB
    maxFiles: 4,
    handleExceptions: true,
    json: false,
    level: 'debug'
});

Is there any way to rotate the logs on app restart so I can see what happenned? Thanks!

Answer 1

You can do that by using a stream , instead of a filename, as an option for the file transport: https://github.com/winstonjs/winston/blob/master/docs/transports.md#file-transport Open a file for appending and then

winston.add(winston.transports.File, { stream: my_already_opened_file} )

If that's not possible, you could try and generate a new filename based on the process number, for instance, or use another logging option. There does not seem to be a way in winston to append existing log files. There are also several ways of generating random or temporary file names: nodejs - Temporary file name but you can always use the filename itself as a store for a sequence name: "log-x.log", por instance, and read the file at the beginning of your program and create another with the sequence number incremented by one