Question: how to use custom logger with the guide 'Exit-Once'

[tzq0301]

https://github.com/uber-go/guide/blob/master/style.md#exit-once

The guide recommend to use log.Fatal(err) to panic the error:

func main() {
  if err := run(); err != nil {
    log.Fatal(err)
  }
}

However, should I try to init my custom logger before I call the run() in main() if I want to use my custom logger to log the error?

Or, is the action 'use my custom logger to log the error' unnecessary to do in the main() func?

[abhinav]

@tzq0301 The example uses log.Fatal because that's what most folks already use when they exit multiple times.
You have a couple options for main, since the purpose of that specific exit it just to print to stderr and exit:

• Use log.Fatal. If you want that to not print timestamps, etc. you can do:

  func main() {
      log.SetFlags(0)
      if err := run(); err != nil {
          log.Fatal(err)
      }
  }

• Print directly to stderr:

  func main() {
      if err := run(); err != nil {
          fmt.Fprintln(os.Stderr, err)
          os.Exit(1)
      }
  }

• Send the exit code back from run(),
  which uses a custom logger:

  func main() {
      os.Exit(run())
  }
  
  func run() (exitCode int) {
      logger := customLogger()
  
      if err := stuff(); err != nil {
          logger.Error("something went wrong", err)
          return 1
      }
  
      return 0
  }

The guidance doesn't aim to be prescriptive about logger/program setup.

Its main thing is only that you should have exactly one place in your program
responsible for calling os.Exit.