How to configure uber-go/zap logger for rolling filesystem log?

If you want to use both console log and rolling log without hook then you can do the following:

// NewProductionZapLogger will return a new production logger backed by zap
func NewProductionZaplogger() (Logger, error) {
    conf := zap.NewProductionConfig()
    conf.Level = zap.NewAtomicLevelAt(zap.DebugLevel)
    conf.DisableCaller = true
    conf.DisableStacktrace = true
    zapLogger, err := conf.Build(zap.WrapCore(zapCore))

    return zpLg{
        lg: zapLogger.Sugar(),
    }, err
}

func zapCore(c zapcore.Core) zapcore.Core {
    // lumberjack.Logger is already safe for concurrent use, so we don't need to
    // lock it.
    w := zapcore.AddSync(&lumberjack.Logger{
        Filename:   "./chat.log",
        MaxSize:    50, // megabytes
        MaxBackups: 30,
        MaxAge:     28, // days
    })

    core := zapcore.NewCore(
        zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()),
        w,
        zap.DebugLevel,
    )
    cores := zapcore.NewTee(c, core)

    return cores
}

I wrote a simpler library rzap for zap and lumberjack.

rzap.NewGlobalLogger([]zapcore.Core{
    rzap.NewCore(&lumberjack.Logger{
        Filename:   "/your/log/path/app.log",
        MaxSize:    10,   // 10 megabytes, defaults to 100 megabytes
        MaxAge:     10,   // 10 days, default is not to remove old log files
        MaxBackups: 10,   // 10 files, default is to retain all old log files
        Compress:   true, // compress to gzio, default is not to perform compression
    }, zap.InfoLevel),
})

zap.L().Info("some message", zap.Int("status", 0))