Refactor logger (#3924)

This patch fixes below

* Previously fatalIf() never writes log other than first logging target.
* quiet flag is not honored to show progress messages other than startup messages.
* Removes console package usage for progress messages.

cmd/console-logger.go

@@ -0,0 +1,74 @@
+/*
+ * Minio Cloud Storage, (C) 2017 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// ConsoleLogger - console logger which logs into stderr.
+type ConsoleLogger struct {
+	BaseLogTarget
+}
+
+// Fire - log entry handler.
+func (logger ConsoleLogger) Fire(entry *logrus.Entry) error {
+	if !logger.Enable {
+		return nil
+	}
+
+	msgBytes, err := logger.formatter.Format(entry)
+	if err == nil {
+		fmt.Fprintf(os.Stderr, string(msgBytes))
+	}
+
+	return err
+}
+
+// String - represents ConsoleLogger as string.
+func (logger ConsoleLogger) String() string {
+	enableStr := "disabled"
+	if logger.Enable {
+		enableStr = "enabled"
+	}
+
+	return fmt.Sprintf("console:%s", enableStr)
+}
+
+// NewConsoleLogger - return new console logger object.
+func NewConsoleLogger() (logger ConsoleLogger) {
+	logger.Enable = true
+	logger.formatter = new(logrus.TextFormatter)
+
+	return logger
+}
+
+// InitConsoleLogger - initializes console logger.
+func InitConsoleLogger(logger *ConsoleLogger) {
+	if !logger.Enable {
+		return
+	}
+
+	if logger.formatter == nil {
+		logger.formatter = new(logrus.TextFormatter)
+	}
+
+	return
+}