go-log

Logging package similar to log4j for the Golang.

• Support dynamic log level
• Daily log file output
• Fixed size log file ouput
• Output console and file all at once
• Output full stack
• Output goroutinue id to console
• Output colorized level to console

Installation

$ go get github.com/subchen/go-log

Usage

Default log to console

package main

import (
    "os"
    "errors"
    "github.com/subchen/go-log"
)

func main() {
    log.Debugf("app = %s", os.Args[0])
    log.Errorf("error = %v", errors.New("some error"))

    // dynamic set level
    log.SetLevel(log.L_INFO)

    log.Debug("cannot output debug message")
    log.Info("can output info message")
}

Output to file

You can call SetWriter to set a file writer into log.

log.SetWriter(&log.FixedSizeFileWriter{
    Name:     "/tmp/test.log",
    MaxSize:  10 * 1024 * 1024, // 10m
    MaxCount: 10,
})

We defined three writers for use

// Create log file if file size large than fixed size (10m)
// files: /tmp/test.log.0 .. test.log.10
&log.FixedSizeFileWriter{
    Name:     "/tmp/test.log",
    MaxSize:  10 * 1024 * 1024, // 10m
    MaxCount: 10,
}

// Create log file every day.
// files: /tmp/test.log.20160102
&log.DailyFileWriter{
    Name: "/tmp/test.log",
    MaxCount: 10,
}

// Create log file every process.
// files: /tmp/test.log.20160102_150405
&log.AlwaysNewFileWriter{
    Name: "/tmp/test.log",
    MaxCount: 10,
}

// Output to multiple writes
io.MultiWriter(
    os.Stdout,
    &log.DailyFileWriter{
        Name: "/tmp/test.log",
        MaxCount: 10,
    }
    //...
)

New log instance

import (
    "github.com/subchen/go-log"
)

func main() {
    logger := log.New(&log.DailyFileWriter{
        Name: "/tmp/test.log",
    })

    logger.Debugf("i = %d", 99)
}

Output stack

You can use log.Fatal(...) or log.Fatalf(...) to output full stack

21:04:32.884 main FATAL logger_test.go:24 this is a fatal message
	at /go/src/github.com/subchen/go-log/logger_test.go:24 (0x81db3)
	at /usr/local/Cellar/go/1.5.2/libexec/src/testing/testing.go:456 (0x786c8)
	at /usr/local/Cellar/go/1.5.2/libexec/src/runtime/asm_amd64.s:1721 (0x59641)

Log format

# time pid [name] [gid] level file:line message
2016-02-10 19:33:02.587 12345 main 987 INFO fixed_size_file_writer_test.go:16 message ...

• log.SetTimeFormat("2006-01-02 15:04:05.999") customize time format
• log.SetAppName("main") add a name in log for indicate process
• log.SetFlags(F_TIME | F_LONG_FILE | F_SHORT_FILE | F_PID | F_GID | F_COLOR) to control what's printed

API on godoc.org

https://godoc.org/github.com/subchen/go-log