Split stdout and stderr in logrus (#108)

* split stdout and stderr

* delete extra line

cmd/root.go

@@ -4,11 +4,11 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/Azure/draft/pkg/logger"
+	cc "github.com/ivanpirog/coloredcobra"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
-	cc "github.com/ivanpirog/coloredcobra"
 	"github.com/spf13/viper"
-	"github.com/Azure/draft/pkg/logger"
 )
 
 var cfgFile string
@@ -33,9 +33,10 @@ For more information, please visit the Draft Github page: https://github.com/Azu
 		if verbose {
 			logrus.SetLevel(logrus.DebugLevel)
 		} else if silent {
-			logrus.SetLevel(logrus.WarnLevel)
+			logrus.SetLevel(logrus.ErrorLevel)
 
 		}
+		logrus.SetOutput(&logger.OutputSplitter{})
 		logrus.SetFormatter(new(logger.CustomFormatter))
 	},
 }

pkg/logger/logger.go

@@ -1,9 +1,12 @@
 package logger
 
 import (
-    log "github.com/sirupsen/logrus"
-    "github.com/fatih/color"
-    "fmt"
+	"bytes"
+	"fmt"
+	"os"
+
+	"github.com/fatih/color"
+	log "github.com/sirupsen/logrus"
 )
 
 type CustomFormatter struct {}
@@ -12,3 +15,12 @@ func (f *CustomFormatter) Format(entry *log.Entry) ([]byte, error) {
     cyan := color.New(color.Bold, color.FgCyan).SprintFunc()
     return []byte(fmt.Sprintf("%s %s\n",cyan("[Draft]"), entry.Message)), nil
 }
+
+type OutputSplitter struct{}
+
+func (splitter *OutputSplitter) Write(p []byte) (n int, err error) {
+	if bytes.Contains(p, []byte("level=error")) ||  bytes.Contains(p, []byte("level=fatal")) || bytes.Contains(p, []byte("level=panic")) {
+		return os.Stderr.Write(p)
+	}
+	return os.Stdout.Write(p)
+}