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logger.go
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logger.go
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// Copyright (c) 2018, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package instance
import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"runtime"
"strings"
"sync"
"syscall"
"time"
)
const (
// BasicLogFormat represents basic log format.
BasicLogFormat = "basic"
// KubernetesLogFormat represents kubernetes log format.
KubernetesLogFormat = "kubernetes"
// JSONLogFormat represents JSON log format.
JSONLogFormat = "json"
)
// LogFormatter implements a log formatter.
type LogFormatter func(stream string, data string) string
func kubernetesLogFormatter(stream, data string) string {
return fmt.Sprintf("%s %s F %s\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
func jsonLogFormatter(stream, data string) string {
return fmt.Sprintf("{\"time\":\"%s\",\"stream\":\"%s\",\"log\":\"%s\"}\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
func basicLogFormatter(stream, data string) string {
if stream != "" {
return fmt.Sprintf("%s %s %s\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
return fmt.Sprintf("%s %s\n", time.Now().Format(time.RFC3339Nano), data)
}
// LogFormats contains supported log format by default.
var LogFormats = map[string]LogFormatter{
BasicLogFormat: basicLogFormatter,
KubernetesLogFormat: kubernetesLogFormatter,
JSONLogFormat: jsonLogFormatter,
}
// Logger defines a file logger.
type Logger struct {
file *os.File
fileMutex sync.Mutex
formatter LogFormatter
}
// NewLogger instantiates a new logger with formatter and return it.
func NewLogger(logPath string, formatter LogFormatter) (*Logger, error) {
logger := &Logger{
formatter: formatter,
}
if logger.formatter == nil {
logger.formatter = basicLogFormatter
}
if err := logger.openFile(logPath); err != nil {
return nil, err
}
return logger, nil
}
func closeFile(file *os.File) {
file.Close()
}
func (l *Logger) openFile(path string) (err error) {
oldmask := syscall.Umask(0)
defer syscall.Umask(oldmask)
l.file, err = os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0644)
if err == nil {
runtime.SetFinalizer(l.file, closeFile)
}
return err
}
func (l *Logger) scanOutput(data []byte, atEOF bool) (advance int, token []byte, err error) {
length := len(data)
if atEOF && length == 0 {
return 0, nil, nil
}
if i := bytes.IndexByte(data, '\n'); i >= 0 {
return i + 1, data[0 : i+1], nil
}
if atEOF {
return length, data[0:length], nil
}
return 0, nil, nil
}
// NewWriter create a new pipe pair for corresponding stream.
func (l *Logger) NewWriter(stream string, dropCRNL bool) *io.PipeWriter {
reader, writer := io.Pipe()
go l.scan(stream, reader, writer, dropCRNL)
return writer
}
func (l *Logger) scan(stream string, pr *io.PipeReader, pw *io.PipeWriter, dropCRNL bool) {
r := strings.NewReplacer("\r", "\\r", "\n", "\\n")
scanner := bufio.NewScanner(pr)
if !dropCRNL {
scanner.Split(l.scanOutput)
}
for scanner.Scan() {
l.fileMutex.Lock()
if !dropCRNL {
fmt.Fprint(l.file, l.formatter(stream, r.Replace(scanner.Text())))
} else {
fmt.Fprint(l.file, l.formatter(stream, scanner.Text()))
}
l.fileMutex.Unlock()
}
pr.Close()
pw.Close()
}
// ReOpenFile closes and re-open log file (eg: log rotation).
func (l *Logger) ReOpenFile() {
l.fileMutex.Lock()
defer l.fileMutex.Unlock()
path := l.file.Name()
l.file.Close()
l.openFile(path)
}