lessgo/logger

lessgo/logger is a Simplified implementation of Leveled logs (google glog).

Example

create a new test file main.go, and input the following codes

package main

import (
    "github.com/lessos/lessgo/logger"
)

func main() {

    // API:Print
    logger.Print("info", "started")
    logger.Print("error", "the error code/message: ", 400, "/", "bad request")

    // API::Printf
    logger.Printf("error", "the error code/message: %d/%s", 400, "bad request")

    select {}
}

build the main.go file, run it and output the log into stderr console

go build main.go
./main -logtostderr=true
I 2016-04-30 22:24:26.463605 main.go:10] started
E 2016-04-30 22:24:26.463620 main.go:11] the error code/message: 400/bad request
E 2016-04-30 22:24:26.463628 main.go:14] the error code/message: 400/bad request

or run it and output the log into file

./main -log_dir="/var/log/"

the output file name will formated like this

/var/log/{program name}.{hostname}.{user name}.log.{level tag}.{date}-{time}.{pid}

log levels

the default log levels are:

Level	Tag
0	debug	Designates fine-grained informational events that are most useful to debug an application.
1	info	Designates informational messages that highlight the progress of the application at coarse-grained level
2	warn	Designates potentially harmful situations
3	error	Designates error events that might still allow the application to continue running
4	fatal	Designates very severe error events that will presumably lead the application to abort

You can also define your custom levels:

logger.LevelConfig([]string{"warn", "error", "fatal"})

Setting Flags

The flags influence lessos/logger's output behavior by passing on the command line. For example, if you want to turn the flag --logtostderr on, you can start your application with the following command line:

./your_application --logtostderr=true

The following flags are most commonly used:

flag	type,default
log_dir	string, default=""	If specified, logfiles are written into this directory; if not specified or the directory does not valid, the logger will not output messages to any logfiles
logtostderr	bool, default=false	If output log messages to stderr
minloglevel	int, default=1(which is INFO)	Log messages at or above this level. Again, the numbers of severity levels DEBUG, INFO, WARN, ERROR, and FATAL are 0, 1, 2, 3, and 4, respectively.
logtolevels	bool, default=false	If output messages to multi leveled logfiles from minloglevel to the max; or output messages to the minloglevel logfile.