logger: Disassociate shared log config between console, file and syslog (#3333)

logurs is not helping us to set different log formats (json/text) to
different loggers. Now, we create different logurs instances and call
them in errorIf and fatalIf

cmd/logger-console-hook.go

@@ -16,11 +16,7 @@
 
 package cmd
 
-import (
-	"io/ioutil"
-
-	"github.com/Sirupsen/logrus"
-)
+import "github.com/Sirupsen/logrus"
 
 // consoleLogger - default logger if not other logging is enabled.
 type consoleLogger struct {
@@ -32,15 +28,19 @@ type consoleLogger struct {
 func enableConsoleLogger() {
 	clogger := serverConfig.GetConsoleLogger()
 	if !clogger.Enable {
-		// Disable console logger if asked for.
-		log.Out = ioutil.Discard
 		return
 	}
 
+	consoleLogger := logrus.New()
+
 	// log.Out and log.Formatter use the default versions.
 	// Only set specific log level.
 	lvl, err := logrus.ParseLevel(clogger.Level)
 	fatalIf(err, "Unknown log level found in the config file.")
 
-	log.Level = lvl
+	consoleLogger.Level = lvl
+	consoleLogger.Formatter = new(logrus.TextFormatter)
+	log.mu.Lock()
+	log.loggers = append(log.loggers, consoleLogger)
+	log.mu.Unlock()
 }

cmd/logger-file-hook.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 
 	"github.com/Sirupsen/logrus"
@@ -43,15 +44,22 @@ func enableFileLogger() {
 	file, err := os.OpenFile(flogger.Filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0666)
 	fatalIf(err, "Unable to open log file.")
 
+	fileLogger := logrus.New()
+
 	// Add a local file hook.
-	log.Hooks.Add(&localFile{file})
+	fileLogger.Hooks.Add(&localFile{file})
 
 	lvl, err := logrus.ParseLevel(flogger.Level)
 	fatalIf(err, "Unknown log level found in the config file.")
 
 	// Set default JSON formatter.
-	log.Formatter = new(logrus.JSONFormatter)
-	log.Level = lvl // Minimum log level.
+	fileLogger.Out = ioutil.Discard
+	fileLogger.Formatter = new(logrus.JSONFormatter)
+	fileLogger.Level = lvl // Minimum log level.
+
+	log.mu.Lock()
+	log.loggers = append(log.loggers, fileLogger)
+	log.mu.Unlock()
 }
 
 // Fire fires the file logger hook and logs to the file.

cmd/logger-syslog-hook_nix.go

@@ -20,6 +20,7 @@ package cmd
 
 import (
 	"fmt"
+	"io/ioutil"
 	"log/syslog"
 
 	"github.com/Sirupsen/logrus"
@@ -43,9 +44,16 @@ func enableSyslogLogger(raddr string) {
 	syslogHook, err := newSyslog("udp", raddr, syslog.LOG_ERR, "MINIO")
 	fatalIf(err, "Unable to initialize syslog logger.")
 
-	log.Hooks.Add(syslogHook)               // Add syslog hook.
-	log.Formatter = &logrus.JSONFormatter{} // JSON formatted log.
-	log.Level = logrus.ErrorLevel           // Minimum log level.
+	sysLogger := logrus.New()
+
+	sysLogger.Hooks.Add(syslogHook)               // Add syslog hook.
+	sysLogger.Formatter = &logrus.JSONFormatter{} // JSON formatted log.
+	sysLogger.Level = logrus.ErrorLevel           // Minimum log level.
+	sysLogger.Out = ioutil.Discard
+
+	log.mu.Lock()
+	log.loggers = append(log.loggers, sysLogger)
+	log.mu.Unlock()
 }
 
 // newSyslog - Creates a hook to be added to an instance of logger.

cmd/logger.go

@@ -21,13 +21,17 @@ import (
 	"path"
 	"runtime"
 	"strings"
+	"sync"
 
 	"github.com/Sirupsen/logrus"
 )
 
 type fields map[string]interface{}
 
-var log = logrus.New() // Default console logger.
+var log = struct {
+	loggers []*logrus.Logger // All registered loggers.
+	mu      sync.Mutex
+}{}
 
 // logger carries logging configuration for various supported loggers.
 // Currently supported loggers are
@@ -69,8 +73,10 @@ func errorIf(err error, msg string, data ...interface{}) {
 		fields["stack"] = strings.Join(e.Trace(), " ")
 	}
 
+	for _, log := range log.loggers {
 		log.WithFields(fields).Errorf(msg, data...)
 	}
+}
 
 // fatalIf wrapper function which takes error and prints jsonic error messages.
 func fatalIf(err error, msg string, data ...interface{}) {
@@ -85,5 +91,7 @@ func fatalIf(err error, msg string, data ...interface{}) {
 	if e, ok := err.(*Error); ok {
 		fields["stack"] = strings.Join(e.Trace(), " ")
 	}
+	for _, log := range log.loggers {
 		log.WithFields(fields).Fatalf(msg, data...)
 	}
+}

cmd/logger_test.go

@@ -39,8 +39,12 @@ func TestCallerLocation(t *testing.T) {
 func TestLogger(t *testing.T) {
 	var buffer bytes.Buffer
 	var fields logrus.Fields
-	log.Out = &buffer
-	log.Formatter = new(logrus.JSONFormatter)
+	testLog := logrus.New()
+	testLog.Out = &buffer
+	testLog.Formatter = new(logrus.JSONFormatter)
+	log.mu.Lock()
+	log.loggers = append(log.loggers, testLog)
+	log.mu.Unlock()
 
 	errorIf(errors.New("Fake error"), "Failed with error.")
 	err := json.Unmarshal(buffer.Bytes(), &fields)