Add JSON logger option (#829)

* add flag to enable json output on logs

cmd/client/lib/cli.go

@@ -78,6 +78,12 @@ var (
 		Name:  "port",
 		Usage: "Local (host:)port for constructed libp2p host to listen on",
 	}
+
+	// JsonFlag is the CLI flag for enabling JSON output for logger
+	JSONFlag = &cli.BoolFlag{
+		Name:  "json",
+		Usage: "Set the output as json format",
+	}
 )
 
 // ClientFlags is a list of common flags for client creation
@@ -90,6 +96,7 @@ var ClientFlags = []cli.Flag{
 	InsecureFlag,
 	RelayFlag,
 	PortFlag,
+	JSONFlag,
 }
 
 // Create builds a client, and can be invoked from a cli action supplied

cmd/client/main.go

@@ -88,14 +88,15 @@ func main() {
 
 // Client loads randomness from a server
 func Client(c *cli.Context) error {
-	// configure logging
-	_ = log.DefaultLogger()
+	var level int
 	if c.Bool(verboseFlag.Name) {
-		log.SetDefaultLogger(os.Stderr, log.LogDebug)
+		level = log.LogDebug
 	} else {
-		log.SetDefaultLogger(os.Stderr, log.LogInfo)
+		level = log.LogInfo
 	}
 
+	log.ConfigureDefaultLogger(os.Stderr, level, c.Bool(lib.JSONFlag.Name))
+
 	opts := []client.Option{}
 
 	if c.IsSet(clientMetricsIDFlag.Name) {

cmd/drand-cli/cli.go

@@ -259,7 +259,8 @@ var appCommands = []*cli.Command{
 		Usage: "Start the drand daemon.",
 		Flags: toArray(folderFlag, tlsCertFlag, tlsKeyFlag,
 			insecureFlag, controlFlag, privListenFlag, pubListenFlag, metricsFlag,
-			certsDirFlag, pushFlag, verboseFlag, enablePrivateRand, oldGroupFlag, skipValidationFlag),
+			certsDirFlag, pushFlag, verboseFlag, enablePrivateRand, oldGroupFlag,
+			skipValidationFlag, jsonFlag),
 		Action: func(c *cli.Context) error {
 			banner()
 			return startCmd(c)
@@ -725,9 +726,9 @@ func contextToConfig(c *cli.Context) *core.Config {
 	version := common.GetAppVersion()
 
 	if c.IsSet(verboseFlag.Name) {
-		opts = append(opts, core.WithLogLevel(log.LogDebug))
+		opts = append(opts, core.WithLogLevel(log.LogDebug, jsonFlag.Value))
 	} else {
-		opts = append(opts, core.WithLogLevel(log.LogInfo))
+		opts = append(opts, core.WithLogLevel(log.LogInfo, jsonFlag.Value))
 	}
 
 	if c.IsSet(pubListenFlag.Name) {

core/config.go

@@ -247,9 +247,13 @@ func WithControlPort(port string) ConfigOption {
 }
 
 // WithLogLevel sets the logging verbosity to the given level.
-func WithLogLevel(level int) ConfigOption {
+func WithLogLevel(level int, jsonFormat bool) ConfigOption {
 	return func(d *Config) {
-		d.logger = log.NewLogger(nil, level)
+		if jsonFormat {
+			d.logger = log.NewJSONLogger(nil, level)
+		} else {
+			d.logger = log.NewLogger(nil, level)
+		}
 	}
 }
 

core/util_test.go

@@ -137,7 +137,7 @@ func BatchNewDrand(t *testing.T, n int, insecure bool, opts ...ConfigOption) (
 
 		confOptions = append(confOptions,
 			WithControlPort(ports[i]),
-			WithLogLevel(log.LogFatal))
+			WithLogLevel(log.LogFatal, false))
 		// add options in last so it overwrites the default
 		confOptions = append(confOptions, opts...)
 
@@ -421,7 +421,7 @@ func (d *DrandTestScenario) CheckPublicBeacon(nodeAddress string, newGroup bool)
 // SetupNewNodes creates new additional nodes that can participate during the resharing
 func (d *DrandTestScenario) SetupNewNodes(t *testing.T, newNodes int) []*MockNode {
 	newDrands, _, newDir, newCertPaths := BatchNewDrand(d.t, newNodes, false,
-		WithCallOption(grpc.WaitForReady(false)), WithLogLevel(log.LogDebug))
+		WithCallOption(grpc.WaitForReady(false)), WithLogLevel(log.LogDebug, false))
 	d.newCertPaths = newCertPaths
 	d.newDir = newDir
 	d.newNodes = make([]*MockNode, newNodes)

demo/node/node_inprocess.go

@@ -86,7 +86,7 @@ func (l *LocalNode) Start(certFolder string) error {
 		return err
 	}
 	opts := []core.ConfigOption{
-		core.WithLogLevel(log.LogDebug),
+		core.WithLogLevel(log.LogDebug, false),
 		core.WithConfigFolder(l.base),
 		core.WithTrustedCerts(certs...),
 		core.WithPublicListenAddress(l.pubAddr),

log/log.go

@@ -2,7 +2,6 @@ package log
 
 import (
 	"os"
-	"sync"
 
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
@@ -39,48 +38,61 @@ const (
 // logger.
 const DefaultLevel = LogInfo
 
-var defaultLoggerSet sync.Once
-
-// SetDefaultLogger updates the default logger to wrap a provided kit logger.
-func SetDefaultLogger(output zapcore.WriteSyncer, level int) {
-	if output == nil {
-		output = os.Stdout
+// ConfigureDefaultLogger updates the default logger to wrap a provided kit logger.
+func ConfigureDefaultLogger(output zapcore.WriteSyncer, level int, jsonFormat bool) {
+	if jsonFormat {
+		zap.ReplaceGlobals(NewZapLogger(output, getJSONEncoder(), level))
+	} else {
+		zap.ReplaceGlobals(NewZapLogger(output, getConsoleEncoder(), level))
 	}
-
-	zap.ReplaceGlobals(NewZapLogger(output, level))
 }
 
 // DefaultLogger is the default logger that only logs at the `DefaultLevel`.
 func DefaultLogger() Logger {
-	defaultLoggerSet.Do(func() {
-		SetDefaultLogger(nil, DefaultLevel)
-	})
+	if zap.S() == nil {
+		zap.ReplaceGlobals(NewZapLogger(nil, getConsoleEncoder(), DefaultLevel))
+	}
 
 	return zap.S()
 }
 
 // NewLogger returns a kit logger that prints statements at the given level.
 func NewLogger(output zapcore.WriteSyncer, level int) Logger {
-	logger := NewZapLogger(output, level)
+	logger := NewZapLogger(output, getConsoleEncoder(), level)
+	return logger.Sugar()
+}
 
+// NewJSONLogger returns a kit logger that prints statements at the given level as JSON output.
+func NewJSONLogger(output zapcore.WriteSyncer, level int) Logger {
+	logger := NewZapLogger(output, getJSONEncoder(), level)
 	return logger.Sugar()
 }
 
-func NewZapLogger(output zapcore.WriteSyncer, level int) *zap.Logger {
+func NewZapLogger(output zapcore.WriteSyncer, encoder zapcore.Encoder, level int) *zap.Logger {
 	if output == nil {
 		output = os.Stdout
 	}
 
+	core := zapcore.NewCore(encoder, output, zapcore.Level(level))
+	logger := zap.New(core, zap.WithCaller(true))
+
+	return logger
+}
+
+func getJSONEncoder() zapcore.Encoder {
 	encoderConfig := zap.NewProductionEncoderConfig()
 
 	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
 	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
 
-	encoder := zapcore.NewConsoleEncoder(encoderConfig)
+	return zapcore.NewJSONEncoder(encoderConfig)
+}
 
-	core := zapcore.NewCore(encoder, output, zapcore.Level(level))
+func getConsoleEncoder() zapcore.Encoder {
+	encoderConfig := zap.NewProductionEncoderConfig()
 
-	logger := zap.New(core, zap.WithCaller(true))
+	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
 
-	return logger
+	return zapcore.NewConsoleEncoder(encoderConfig)
 }