Change log level at runtime?

[mrichman]

Can I change the log level at runtime? For example, if I have a flag --debug then set DebugLevel.

I'm using urfave/cli (formerly codegangsta/cli) to access flags.

[tomnz]

logrus.SetLevel( ... )

[flowchartsman]

@mrichman please close this issue as your question has been answered.

[ku9nov]

The actual answer is correct, but it's not fully formed, which is why there are so many negative reactions to it. So, I think it would be helpful to add a simple example of how this can be used to change the log level at runtime.

package main

import (
	"flag"
	"fmt"
	"os"

	"github.com/sirupsen/logrus"
)

var logLevel string

func init() {
	flag.StringVar(&logLevel, "loglevel", "info", "log level (debug, info, warn, error, fatal, panic)")
	flag.Parse()

	logrus.New()

	level, err := logrus.ParseLevel(logLevel)
	if err != nil {
		fmt.Println("Invalid log level specified:", err)
		os.Exit(1)
	}
	logrus.SetLevel(level)
	logrus.SetFormatter(&logrus.TextFormatter{
		FullTimestamp: true,
	})
}

func main() {
	logrus.Info("Starting application...")
	logrus.Debug("Debug test")
	logrus.Info("Application finished.")
}

In this case, if we run the application with the info flag, we'll get:

go run ./... -loglevel=info
INFO[2024-05-09T18:39:19+03:00] Starting application...
INFO[2024-05-09T18:39:19+03:00] Application finished.

And if we run it with the debug flag, we'll get:

go run ./... -loglevel=debug
INFO[2024-05-09T18:39:21+03:00] Starting application...
DEBU[2024-05-09T18:39:22+03:00] Debug test
INFO[2024-05-09T18:39:22+03:00] Application finished.

This shows how you can dynamically change the log level when running the application.