How to send log to a different location : UberZap

Question

I need to send logs to the different location in go zap logger.

How can I do that?

Answer 1

zap can send logs to anything that implemnts the WriteSyncer interface. Which is simply an io.Writer which has a Sync method. If you need to add a no-op Sync method you can use zapcore.AddSync, or if you need it to be safe for concurrent you can add a protecting mutex with zapcore.Lock.

Basically you'd have something like

var output zapcore.WriteSyncer = os.Stdout // for example
zapOutput := zapcore.Lock(output)
encoder := zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
// you could also use zap.NewDevelopmentEncoderConfig()
// define what level you want to log
priority := zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
    return lvl >= zapcore.ErrorLevel
})
// Join the outputs, encoders, and level-handling functions into
// zapcore.Cores, then tee the four cores together.
core := zapcore.NewTee(
    zapcore.NewCore(encoder, zapOutput, priority),
    // you can add other cores here to log to multiple places
)

logger := zap.New(core) // this is your logger
defer logger.Sync()     // don't forget to sync
logger.Info("constructed a logger") // example log

See the docs for more detail.