Add logging example for the different levels.

[sethlinnkuleuven]

I think it would be nice if this module contained examples on the proper/ cleanest way to log messages at different levels(DEBUG, INFO, etc...) I noticed that even the standard Printf() turns into an error level in debug.log

log.Printf("Hello World") results in {"level":"error","module":.....................................

Thank you

[sebinsua]

Did you figure out a way to achieve this?

Edit:

I'm only able to get 'debug' or 'error' logs and have done so with this:

package logger

import (
    "fmt"
    "log"
    "strings"
)

type Logger struct {
    _info   func(args ...interface{})
    _debug  func(args ...interface{})
    _error  func(args ...interface{})
    _infof  func(format string, args ...interface{})
    _debugf func(format string, args ...interface{})
    _errorf func(format string, args ...interface{})
}

func NewLogger(_logLevel string) *Logger {
    logLevel := strings.ToLower(_logLevel)
    // This globally sets the flags for the standard logger which is generally
    // a bad practice, however, since Traefik is capturing the output of the
    // logger and redirecting it to its own logger, this is the only way to
    // ensure that the error logs are not prefixed by the date and time, and
    // has no other side effects.
    log.SetFlags(0)

    logger := &Logger{
        _debug: func(args ...interface{}) {
            fmt.Println(args...)
        },
        _info: func(args ...interface{}) {
            fmt.Println(args...)
        },
        _error: func(args ...interface{}) {
            log.Println(args...)
        },
        _debugf: func(format string, args ...interface{}) {
            fmt.Printf(format+"\n", args...)
        },
        _infof: func(format string, args ...interface{}) {
            fmt.Printf(format+"\n", args...)
        },
        _errorf: func(format string, args ...interface{}) {
            log.Printf(format+"\n", args...)
        },
    }

    noopLog := func(args ...interface{}) {}
    noopLogf := func(format string, args ...interface{}) {}

    switch logLevel {
    default:
    case "error":
        logger._debug = noopLog
        logger._debugf = noopLogf
        logger._info = noopLog
        logger._infof = noopLogf
    case "info":
        logger._debug = noopLog
        logger._debugf = noopLogf
    case "debug":
        break
    }

    return logger
}

func (l *Logger) Debug(args ...interface{}) {
    l._debug(args...)
}

func (l *Logger) Info(args ...interface{}) {
    l._info(args...)
}

func (l *Logger) Error(args ...interface{}) {
    l._error(args...)
}

func (l *Logger) Debugf(format string, args ...interface{}) {
    l._debugf(format, args...)
}

func (l *Logger) Infof(format string, args ...interface{}) {
    l._infof(format, args...)
}

func (l *Logger) Errorf(format string, args ...interface{}) {
    l._errorf(format, args...)
}

[sethlinnkuleuven]

Wow! That is allot farther than I have gotten. I just comment or uncomment for nw. Was hoping someone at Traefik would pick this up.