set log format using a flag

cmd/executor/cmd/root.go

@@ -28,6 +28,7 @@ import (
 	"github.com/GoogleContainerTools/kaniko/pkg/config"
 	"github.com/GoogleContainerTools/kaniko/pkg/constants"
 	"github.com/GoogleContainerTools/kaniko/pkg/executor"
+	"github.com/GoogleContainerTools/kaniko/pkg/logging"
 	"github.com/GoogleContainerTools/kaniko/pkg/timing"
 	"github.com/GoogleContainerTools/kaniko/pkg/util"
 	"github.com/genuinetools/amicontained/container"
@@ -38,13 +39,12 @@ import (
 )
 
 var (
-	opts     = &config.KanikoOptions{}
-	logLevel string
-	force    bool
+	opts  = &config.KanikoOptions{}
+	force bool
 )
 
 func init() {
-	RootCmd.PersistentFlags().StringVarP(&logLevel, "verbosity", "v", constants.DefaultLogLevel, "Log level (debug, info, warn, error, fatal, panic")
+	logging.AddFlags(RootCmd.PersistentFlags())
 	RootCmd.PersistentFlags().BoolVarP(&force, "force", "", false, "Force building outside of a container")
 	addKanikoOptionsFlags()
 	addHiddenFlags(RootCmd)
@@ -56,7 +56,7 @@ var RootCmd = &cobra.Command{
 	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 		if cmd.Use == "executor" {
 			resolveEnvironmentBuildArgs(opts.BuildArgs, os.Getenv)
-			if err := util.ConfigureLogging(logLevel); err != nil {
+			if err := logging.Configure(); err != nil {
 				return err
 			}
 			if !opts.NoPush && len(opts.Destinations) == 0 {

cmd/warmer/cmd/root.go

@@ -23,27 +23,25 @@ import (
 
 	"github.com/GoogleContainerTools/kaniko/pkg/cache"
 	"github.com/GoogleContainerTools/kaniko/pkg/config"
-	"github.com/GoogleContainerTools/kaniko/pkg/constants"
-	"github.com/GoogleContainerTools/kaniko/pkg/util"
+	"github.com/GoogleContainerTools/kaniko/pkg/logging"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 )
 
 var (
-	opts     = &config.WarmerOptions{}
-	logLevel string
+	opts = &config.WarmerOptions{}
 )
 
 func init() {
-	RootCmd.PersistentFlags().StringVarP(&logLevel, "verbosity", "v", constants.DefaultLogLevel, "Log level (debug, info, warn, error, fatal, panic")
+	logging.AddFlags(RootCmd.PersistentFlags())
 	addKanikoOptionsFlags()
 	addHiddenFlags()
 }
 
 var RootCmd = &cobra.Command{
 	Use: "cache warmer",
 	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
-		if err := util.ConfigureLogging(logLevel); err != nil {
+		if err := logging.Configure(); err != nil {
 			return err
 		}
 		if len(opts.Images) == 0 {

pkg/constants/constants.go

@@ -17,9 +17,6 @@ limitations under the License.
 package constants
 
 const (
-	// DefaultLogLevel is the default log level
-	DefaultLogLevel = "info"
-
 	// RootDir is the path to the root directory
 	RootDir = "/"
 

pkg/logging/logging.go

@@ -0,0 +1,60 @@
+package logging
+
+import (
+	"fmt"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/pflag"
+)
+
+const (
+	// Default log level
+	DefaultLevel = "info"
+
+	// Text format
+	FormatText = "text"
+	// Colored text format
+	FormatColor = "color"
+	// JSON format
+	FormatJSON = "json"
+)
+
+var (
+	logLevel  string
+	logFormat string
+)
+
+// AddFlags injects logging-related flags into the given FlagSet
+func AddFlags(fs *pflag.FlagSet) {
+	fs.StringVarP(&logLevel, "verbosity", "v", DefaultLevel, "Log level (debug, info, warn, error, fatal, panic")
+	fs.StringVar(&logFormat, "log-format", FormatColor, "Log format (text, color, json)")
+}
+
+// Configure sets the logrus logging level and formatter
+func Configure() error {
+	lvl, err := logrus.ParseLevel(logLevel)
+	if err != nil {
+		return errors.Wrap(err, "parsing log level")
+	}
+	logrus.SetLevel(lvl)
+
+	var formatter logrus.Formatter
+	switch logFormat {
+	case FormatText:
+		formatter = &logrus.TextFormatter{
+			DisableColors: true,
+		}
+	case FormatColor:
+		formatter = &logrus.TextFormatter{
+			ForceColors: true,
+		}
+	case FormatJSON:
+		formatter = &logrus.JSONFormatter{}
+	default:
+		return fmt.Errorf("not a valid log format: %q", logFormat)
+	}
+	logrus.SetFormatter(formatter)
+
+	return nil
+}

pkg/util/util.go

@@ -28,25 +28,10 @@ import (
 	"syscall"
 
 	"github.com/minio/highwayhash"
-	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
 
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 )
 
-// ConfigureLogging sets the logrus logging level and forces logs to be colorful (!)
-func ConfigureLogging(logLevel string) error {
-	lvl, err := logrus.ParseLevel(logLevel)
-	if err != nil {
-		return errors.Wrap(err, "parsing log level")
-	}
-	logrus.SetLevel(lvl)
-	logrus.SetFormatter(&logrus.TextFormatter{
-		ForceColors: true,
-	})
-	return nil
-}
-
 // Hasher returns a hash function, used in snapshotting to determine if a file has changed
 func Hasher() func(string) (string, error) {
 	pool := sync.Pool{