Bunyan higher levels logging into lower level streams

Question

I am trying to use bunyan in my nodejs application, however I stuck with this bizarre behaviour. Defining the logger like so:

var info = bunyan.createLogger({
    name: 'Test',
    streams: [
        {
            path: './logger/fatal.log',
            level: 'fatal'
        },
        {
            path: './logger/error.log',
            level: 'error'
        },
        {
            path: './logger/warn.log',
            level: 'warn'
        },
        {
            path: './logger/info.log',
            level: 'info'
        },
        {
            path: './logger/debug.log',
            level: 'debug'
        },
        {
            path: './logger/trace.log',
            level: 'trace'
        }
    ]
});

And I am calling them in a function like so:

var func = function () {
    info.fatal("FATAL!");
    info.error("ERROR!");
    info.warn("WARN!");
    info.debug("DEBUG!");
    info.info("INFO");
    info.trace("TRACE");
}

Now the predictable behaviour would be fatal.log has {"name":"Test","hostname":"ENIGMA","pid":16793,"level":60,"msg":"FATAL!","time":"2016-01-21T09:12:34.293Z","v":0}

and error.log has {"name":"Test","hostname":"ENIGMA","pid":16793,"level":50,"msg":"ERROR!","time":"2016-01-21T09:12:34.295Z","v":0} and so forth.

However, on my application, fatal.log has {"name":"Test","hostname":"ENIGMA","pid":16793,"level":60,"msg":"FATAL!","time":"2016-01-21T09:12:34.293Z","v":0}

error.log has {"name":"Test","hostname":"ENIGMA","pid":16793,"level":60,"msg":"FATAL!","time":"2016-01-21T09:12:34.293Z","v":0} {"name":"Test","hostname":"ENIGMA","pid":16793,"level":50,"msg":"ERROR!","time":"2016-01-21T09:12:34.295Z","v":0}

warn.log has {"name":"Test","hostname":"ENIGMA","pid":16793,"level":60,"msg":"FATAL!","time":"2016-01-21T09:12:34.293Z","v":0} {"name":"Test","hostname":"ENIGMA","pid":16793,"level":50,"msg":"ERROR!","time":"2016-01-21T09:12:34.295Z","v":0} {"name":"Test","hostname":"ENIGMA","pid":16793,"level":40,"msg":"WARN!","time":"2016-01-21T09:12:34.296Z","v":0}

and so forth.

The higher level logs are getting into the lower streams. How do I prevent this behaviour and make each level log into its own specific file? (I have also reported an issue at node-bunyan)

Answer 1

This is part of the design of a logger. The higher levels will always get logged into lower levels too. So the last level will be the most verbose of them all.