Add logger command - also migrate from old config to newer config

logger-file-hook.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/minio/minio-xl/pkg/probe"
+)
+
+type localFile struct {
+	*os.File
+}
+
+func log2File(filename string) *probe.Error {
+	fileHook, e := newFile(filename)
+	if e != nil {
+		return probe.NewError(e)
+	}
+	log.Hooks.Add(fileHook)                 // Add a local file hook.
+	log.Formatter = &logrus.JSONFormatter{} // JSON formatted log.
+	log.Level = logrus.InfoLevel            // Minimum log level.
+	return nil
+}
+
+func newFile(filename string) (*localFile, error) {
+	file, err := os.OpenFile(filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+	if err != nil {
+		return nil, err
+	}
+	return &localFile{file}, nil
+}
+
+func (l *localFile) Fire(entry *logrus.Entry) error {
+	line, err := entry.String()
+	if err != nil {
+		return fmt.Errorf("Unable to read entry, %v", err)
+	}
+	l.File.Write([]byte(line + "\n"))
+	l.File.Sync()
+	return nil
+}
+
+// Levels -
+func (l *localFile) Levels() []logrus.Level {
+	return []logrus.Level{
+		logrus.PanicLevel,
+		logrus.FatalLevel,
+		logrus.ErrorLevel,
+		logrus.WarnLevel,
+		logrus.InfoLevel,
+		logrus.DebugLevel,
+	}
+}