package logging import ( "fmt" "io" "os" "strings" "sync" "time" "github.com/pkg/errors" ) type Logger struct { file io.WriteCloser toStdout bool mut sync.Mutex } // NewLogger creates a Logger instance with given filename and // toStdout tells wether to write to Stdout as well or not. func NewLogger(path string, toStdout bool) (*Logger, error) { f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0660) if err != nil { return nil, errors.Wrap(err, "failed to open log file") } return &Logger{file: f, toStdout: toStdout}, nil } func (l *Logger) Println(v ...interface{}) { l.mut.Lock() defer l.mut.Unlock() nowStr := time.Now().UTC().Format(time.RFC3339) fmt.Fprintln(l.file, nowStr, v) if l.toStdout { fmt.Println(v...) } } func (l *Logger) Printf(format string, v ...interface{}) { l.mut.Lock() defer l.mut.Unlock() // Ensure a new line will be written if !strings.HasSuffix(format, "\n") { format += "\n" } nowStr := time.Now().UTC().Format(time.RFC3339) fmt.Fprintf(l.file, nowStr+" "+format, v...) if l.toStdout { fmt.Printf(format, v...) } } func (l *Logger) Fatalln(v ...interface{}) { l.mut.Lock() nowStr := time.Now().UTC().Format(time.RFC3339) fmt.Fprintln(l.file, nowStr, v) if l.toStdout { fmt.Println(v...) } l.file.Close() os.Exit(1) } func (l *Logger) Fatalf(format string, v ...interface{}) { l.mut.Lock() // Ensure a new line will be written if !strings.HasSuffix(format, "\n") { format += "\n" } nowStr := time.Now().UTC().Format(time.RFC3339) fmt.Fprintf(l.file, nowStr+" "+format, v...) if l.toStdout { fmt.Printf(format, v...) } l.file.Close() os.Exit(1) } func (l *Logger) Close() error { return l.file.Close() }