Add log forrmat options

Author: ashald

.gitignore

@@ -5,4 +5,4 @@
 docker-volume-loopback
 
 plugin/rootfs
-tmp
+

context/context.go

@@ -6,9 +6,11 @@ import (
 	"github.com/sirupsen/logrus"
 	"io"
 	"math/rand"
+	"strings"
 	"time"
 )
 
+// Log levels
 const (
 	Error   = 0
 	Warning = 1
@@ -25,6 +27,23 @@ var allLevels = []logrus.Level{
 	logrus.TraceLevel,
 }
 
+// Log formats
+const (
+	FormatJson = "json"
+	FormatText = "text"
+	FormatNice = "nice"
+)
+
+var formats = map[string]logrus.Formatter{
+	FormatJson: &logrus.JSONFormatter{},
+	FormatText: &logrus.TextFormatter{
+		DisableColors: true,
+		FullTimestamp: true,
+	},
+	FormatNice: &logrus.TextFormatter{},
+}
+var allFormats = []string{FormatJson, FormatText, FormatNice}
+
 type Fields map[string]interface{}
 
 type Context struct {
@@ -35,8 +54,15 @@ type Context struct {
 	fields map[string]interface{}
 }
 
-func Init(level int, output io.Writer) {
-	logrus.SetFormatter(&logrus.JSONFormatter{})
+func Init(level int, format string, output io.Writer) {
+	formatter, valid := formats[format]
+	if !valid {
+		panic(
+			fmt.Sprintf(
+				"Wrong log format '%s' - only following are supported: %s",
+				format, strings.Join(allFormats, ", ")))
+	}
+	logrus.SetFormatter(formatter)
 	logrus.SetOutput(output)
 	logrus.SetLevel(convertLevel(level))
 }

main.go

@@ -14,6 +14,7 @@ import (
 type config struct {
 	Socket      string `arg:"--socket,env:SOCKET,help:path to the plugin UNIX socket under /run/docker/plugins/"`
 	LogLevel    int    `arg:"--log-level,env:LOG_LEVEL,help:set log level - from 0 to 4 for Error/Warning/Info/Debug/Trace"`
+	LogFormat   string `arg:"--log-format,env:LOG_FORMAT,help:set log format - json/text/nice"`
 	StateDir    string `arg:"--state-dir,env:STATE_DIR,help:dir used to keep track of currently mounted volumes"`
 	DataDir     string `arg:"--data-dir,env:DATA_DIR,help:dir used to store actual volume data"`
 	MountDir    string `arg:"--mount-dir,env:MOUNT_DIR,help:dir used to create mount-points"`
@@ -28,13 +29,14 @@ var (
 		MountDir:    "/mnt",
 		DefaultSize: "1GiB",
 		LogLevel:    0,
+		LogFormat:   context.FormatNice,
 	}
 )
 
 func main() {
 	arg.MustParse(args)
 
-	context.Init(args.LogLevel, os.Stdout)
+	context.Init(args.LogLevel, args.LogFormat, os.Stdout)
 
 	ctx := context.New()