diff --git a/core/logx/config.go b/core/logx/config.go
index 87d02684..41f52981 100644
--- a/core/logx/config.go
+++ b/core/logx/config.go
@@ -1,5 +1,6 @@
 package logx
 
+// A LogConf is a logging config.
 type LogConf struct {
 	ServiceName         string `json:",optional"`
 	Mode                string `json:",default=console,options=console|file|volume"`
diff --git a/core/logx/durationlogger.go b/core/logx/durationlogger.go
index 45fe5524..d6832076 100644
--- a/core/logx/durationlogger.go
+++ b/core/logx/durationlogger.go
@@ -12,6 +12,7 @@ const durationCallerDepth = 3
 
 type durationLogger logEntry
 
+// WithDuration returns a Logger which logs the given duration.
 func WithDuration(d time.Duration) Logger {
 	return &durationLogger{
 		Duration: timex.ReprOfDuration(d),
diff --git a/core/logx/lesslogger.go b/core/logx/lesslogger.go
index 15c878a6..94200ca6 100644
--- a/core/logx/lesslogger.go
+++ b/core/logx/lesslogger.go
@@ -1,21 +1,25 @@
 package logx
 
+// A LessLogger is a logger that control to log once during the given duration.
 type LessLogger struct {
 	*limitedExecutor
 }
 
+// NewLessLogger returns a LessLogger.
 func NewLessLogger(milliseconds int) *LessLogger {
 	return &LessLogger{
 		limitedExecutor: newLimitedExecutor(milliseconds),
 	}
 }
 
+// Error logs v into error log or discard it if more than once in the given duration.
 func (logger *LessLogger) Error(v ...interface{}) {
 	logger.logOrDiscard(func() {
 		Error(v...)
 	})
 }
 
+// Errorf logs v with format into error log or discard it if more than once in the given duration.
 func (logger *LessLogger) Errorf(format string, v ...interface{}) {
 	logger.logOrDiscard(func() {
 		Errorf(format, v...)
diff --git a/core/logx/lesswriter.go b/core/logx/lesswriter.go
index 4fec9abd..b85396a3 100644
--- a/core/logx/lesswriter.go
+++ b/core/logx/lesswriter.go
@@ -7,7 +7,7 @@ type lessWriter struct {
 	writer io.Writer
 }
 
-func NewLessWriter(writer io.Writer, milliseconds int) *lessWriter {
+func newLessWriter(writer io.Writer, milliseconds int) *lessWriter {
 	return &lessWriter{
 		limitedExecutor: newLimitedExecutor(milliseconds),
 		writer:          writer,
diff --git a/core/logx/lesswriter_test.go b/core/logx/lesswriter_test.go
index 2b72d011..799d64d1 100644
--- a/core/logx/lesswriter_test.go
+++ b/core/logx/lesswriter_test.go
@@ -9,7 +9,7 @@ import (
 
 func TestLessWriter(t *testing.T) {
 	var builder strings.Builder
-	w := NewLessWriter(&builder, 500)
+	w := newLessWriter(&builder, 500)
 	for i := 0; i < 100; i++ {
 		_, err := w.Write([]byte("hello"))
 		assert.Nil(t, err)
diff --git a/core/logx/logs.go b/core/logx/logs.go
index 98b57b27..8ef42a10 100644
--- a/core/logx/logs.go
+++ b/core/logx/logs.go
@@ -57,8 +57,11 @@ const (
 )
 
 var (
-	ErrLogPathNotSet        = errors.New("log path must be set")
-	ErrLogNotInitialized    = errors.New("log not initialized")
+	// ErrLogPathNotSet is an error that indicates the log path is not set.
+	ErrLogPathNotSet = errors.New("log path must be set")
+	// ErrLogNotInitialized is an error that log is not initialized.
+	ErrLogNotInitialized = errors.New("log not initialized")
+	// ErrLogServiceNameNotSet is an error that indicates that the service name is not set.
 	ErrLogServiceNameNotSet = errors.New("log service name must be set")
 
 	writeConsole bool
@@ -89,8 +92,10 @@ type (
 		keepDays              int
 	}
 
+	// LogOption defines the method to customize the logging.
 	LogOption func(options *logOptions)
 
+	// A Logger represents a logger.
 	Logger interface {
 		Error(...interface{})
 		Errorf(string, ...interface{})
@@ -102,6 +107,7 @@ type (
 	}
 )
 
+// MustSetup sets up logging with given config c. It exits on error.
 func MustSetup(c LogConf) {
 	Must(SetUp(c))
 }
@@ -122,10 +128,12 @@ func SetUp(c LogConf) error {
 	}
 }
 
+// Alert alerts v in alert level, and the message is written to error log.
 func Alert(v string) {
 	output(errorLog, levelAlert, v)
 }
 
+// Close closes the logging.
 func Close() error {
 	if writeConsole {
 		return nil
@@ -170,6 +178,7 @@ func Close() error {
 	return nil
 }
 
+// Disable disables the logging.
 func Disable() {
 	once.Do(func() {
 		atomic.StoreUint32(&initialized, 1)
@@ -183,40 +192,49 @@ func Disable() {
 	})
 }
 
+// Error writes v into error log.
 func Error(v ...interface{}) {
 	ErrorCaller(1, v...)
 }
 
+// Errorf writes v with format into error log.
 func Errorf(format string, v ...interface{}) {
 	ErrorCallerf(1, format, v...)
 }
 
+// ErrorCaller writes v with context into error log.
 func ErrorCaller(callDepth int, v ...interface{}) {
 	errorSync(fmt.Sprint(v...), callDepth+callerInnerDepth)
 }
 
+// ErrorCallerf writes v with context in format into error log.
 func ErrorCallerf(callDepth int, format string, v ...interface{}) {
 	errorSync(fmt.Sprintf(format, v...), callDepth+callerInnerDepth)
 }
 
+// ErrorStack writes v along with call stack into error log.
 func ErrorStack(v ...interface{}) {
 	// there is newline in stack string
 	stackSync(fmt.Sprint(v...))
 }
 
+// ErrorStackf writes v along with call stack in format into error log.
 func ErrorStackf(format string, v ...interface{}) {
 	// there is newline in stack string
 	stackSync(fmt.Sprintf(format, v...))
 }
 
+// Info writes v into access log.
 func Info(v ...interface{}) {
 	infoSync(fmt.Sprint(v...))
 }
 
+// Infof writes v with format into access log.
 func Infof(format string, v ...interface{}) {
 	infoSync(fmt.Sprintf(format, v...))
 }
 
+// Must checks if err is nil, otherwise logs the err and exits.
 func Must(err error) {
 	if err != nil {
 		msg := formatWithCaller(err.Error(), 3)
@@ -226,46 +244,56 @@ func Must(err error) {
 	}
 }
 
+// SetLevel sets the logging level. It can be used to suppress some logs.
 func SetLevel(level uint32) {
 	atomic.StoreUint32(&logLevel, level)
 }
 
+// Severe writes v into severe log.
 func Severe(v ...interface{}) {
 	severeSync(fmt.Sprint(v...))
 }
 
+// Severef writes v with format into severe log.
 func Severef(format string, v ...interface{}) {
 	severeSync(fmt.Sprintf(format, v...))
 }
 
+// Slow writes v into slow log.
 func Slow(v ...interface{}) {
 	slowSync(fmt.Sprint(v...))
 }
 
+// Slowf writes v with format into slow log.
 func Slowf(format string, v ...interface{}) {
 	slowSync(fmt.Sprintf(format, v...))
 }
 
+// Stat writes v into stat log.
 func Stat(v ...interface{}) {
 	statSync(fmt.Sprint(v...))
 }
 
+// Statf writes v with format into stat log.
 func Statf(format string, v ...interface{}) {
 	statSync(fmt.Sprintf(format, v...))
 }
 
+// WithCooldownMillis customizes logging on writting call stack interval.
 func WithCooldownMillis(millis int) LogOption {
 	return func(opts *logOptions) {
 		opts.logStackCooldownMills = millis
 	}
 }
 
+// WithKeepDays customizes logging to keep logs with days.
 func WithKeepDays(days int) LogOption {
 	return func(opts *logOptions) {
 		opts.keepDays = days
 	}
 }
 
+// WithGzip customizes logging to automatically gzip the log files.
 func WithGzip() LogOption {
 	return func(opts *logOptions) {
 		opts.gzipEnabled = true
@@ -382,7 +410,7 @@ func setupWithConsole(c LogConf) {
 		errorLog = newLogWriter(log.New(os.Stderr, "", flags))
 		severeLog = newLogWriter(log.New(os.Stderr, "", flags))
 		slowLog = newLogWriter(log.New(os.Stderr, "", flags))
-		stackLog = NewLessWriter(errorLog, options.logStackCooldownMills)
+		stackLog = newLessWriter(errorLog, options.logStackCooldownMills)
 		statLog = infoLog
 	})
 }
@@ -434,7 +462,7 @@ func setupWithFiles(c LogConf) error {
 			return
 		}
 
-		stackLog = NewLessWriter(errorLog, options.logStackCooldownMills)
+		stackLog = newLessWriter(errorLog, options.logStackCooldownMills)
 	})
 
 	return err
diff --git a/core/logx/rotatelogger.go b/core/logx/rotatelogger.go
index ec2261a6..c615f070 100644
--- a/core/logx/rotatelogger.go
+++ b/core/logx/rotatelogger.go
@@ -26,9 +26,11 @@ const (
 	defaultFileMode = 0600
 )
 
+// ErrLogFileClosed is an error that indicates the log file is already closed.
 var ErrLogFileClosed = errors.New("error: log file closed")
 
 type (
+	// A RotateRule interface is used to define the log rotating rules.
 	RotateRule interface {
 		BackupFileName() string
 		MarkRotated()
@@ -36,6 +38,7 @@ type (
 		ShallRotate() bool
 	}
 
+	// A RotateLogger is a Logger that can rotate log files with given rules.
 	RotateLogger struct {
 		filename string
 		backup   string
@@ -50,6 +53,7 @@ type (
 		closeOnce sync.Once
 	}
 
+	// A DailyRotateRule is a rule to daily rotate the log files.
 	DailyRotateRule struct {
 		rotatedTime string
 		filename    string
@@ -59,6 +63,7 @@ type (
 	}
 )
 
+// DefaultRotateRule is a default log rotating rule, currently DailyRotateRule.
 func DefaultRotateRule(filename, delimiter string, days int, gzip bool) RotateRule {
 	return &DailyRotateRule{
 		rotatedTime: getNowDate(),
@@ -69,14 +74,17 @@ func DefaultRotateRule(filename, delimiter string, days int, gzip bool) RotateRu
 	}
 }
 
+// BackupFileName returns the backup filename on rotating.
 func (r *DailyRotateRule) BackupFileName() string {
 	return fmt.Sprintf("%s%s%s", r.filename, r.delimiter, getNowDate())
 }
 
+// MarkRotated marks the rotated time of r to be the current time.
 func (r *DailyRotateRule) MarkRotated() {
 	r.rotatedTime = getNowDate()
 }
 
+// OutdatedFiles returns the files that exceeded the keeping days.
 func (r *DailyRotateRule) OutdatedFiles() []string {
 	if r.days <= 0 {
 		return nil
@@ -113,10 +121,12 @@ func (r *DailyRotateRule) OutdatedFiles() []string {
 	return outdates
 }
 
+// ShallRotate checks if the file should be rotated.
 func (r *DailyRotateRule) ShallRotate() bool {
 	return len(r.rotatedTime) > 0 && getNowDate() != r.rotatedTime
 }
 
+// NewLogger returns a RotateLogger with given filename and rule, etc.
 func NewLogger(filename string, rule RotateRule, compress bool) (*RotateLogger, error) {
 	l := &RotateLogger{
 		filename: filename,
@@ -133,6 +143,7 @@ func NewLogger(filename string, rule RotateRule, compress bool) (*RotateLogger,
 	return l, nil
 }
 
+// Close closes l.
 func (l *RotateLogger) Close() error {
 	var err error
 
diff --git a/core/logx/tracelogger.go b/core/logx/tracelogger.go
index b07a22ee..a40602bb 100644
--- a/core/logx/tracelogger.go
+++ b/core/logx/tracelogger.go
@@ -67,6 +67,7 @@ func (l *traceLogger) write(writer io.Writer, level, content string) {
 	outputJson(writer, l)
 }
 
+// WithContext sets ctx to log, for keeping tracing infomation.
 func WithContext(ctx context.Context) Logger {
 	return &traceLogger{
 		ctx: ctx,
diff --git a/core/logx/tracelogger_test.go b/core/logx/tracelogger_test.go
index 37e7cfef..68735a12 100644
--- a/core/logx/tracelogger_test.go
+++ b/core/logx/tracelogger_test.go
@@ -13,8 +13,8 @@ import (
 )
 
 const (
-	mockTraceId = "mock-trace-id"
-	mockSpanId  = "mock-span-id"
+	mockTraceID = "mock-trace-id"
+	mockSpanID  = "mock-span-id"
 )
 
 var mock tracespec.Trace = new(mockTrace)
@@ -24,8 +24,8 @@ func TestTraceLog(t *testing.T) {
 	atomic.StoreUint32(&initialized, 1)
 	ctx := context.WithValue(context.Background(), tracespec.TracingKey, mock)
 	WithContext(ctx).(*traceLogger).write(&buf, levelInfo, testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 }
 
 func TestTraceError(t *testing.T) {
@@ -36,12 +36,12 @@ func TestTraceError(t *testing.T) {
 	l := WithContext(ctx).(*traceLogger)
 	SetLevel(InfoLevel)
 	l.WithDuration(time.Second).Error(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 	buf.Reset()
 	l.WithDuration(time.Second).Errorf(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 }
 
 func TestTraceInfo(t *testing.T) {
@@ -52,12 +52,12 @@ func TestTraceInfo(t *testing.T) {
 	l := WithContext(ctx).(*traceLogger)
 	SetLevel(InfoLevel)
 	l.WithDuration(time.Second).Info(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 	buf.Reset()
 	l.WithDuration(time.Second).Infof(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 }
 
 func TestTraceSlow(t *testing.T) {
@@ -68,12 +68,12 @@ func TestTraceSlow(t *testing.T) {
 	l := WithContext(ctx).(*traceLogger)
 	SetLevel(InfoLevel)
 	l.WithDuration(time.Second).Slow(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 	buf.Reset()
 	l.WithDuration(time.Second).Slowf(testlog)
-	assert.True(t, strings.Contains(buf.String(), mockTraceId))
-	assert.True(t, strings.Contains(buf.String(), mockSpanId))
+	assert.True(t, strings.Contains(buf.String(), mockTraceID))
+	assert.True(t, strings.Contains(buf.String(), mockSpanID))
 }
 
 func TestTraceWithoutContext(t *testing.T) {
@@ -83,22 +83,22 @@ func TestTraceWithoutContext(t *testing.T) {
 	l := WithContext(context.Background()).(*traceLogger)
 	SetLevel(InfoLevel)
 	l.WithDuration(time.Second).Info(testlog)
-	assert.False(t, strings.Contains(buf.String(), mockTraceId))
-	assert.False(t, strings.Contains(buf.String(), mockSpanId))
+	assert.False(t, strings.Contains(buf.String(), mockTraceID))
+	assert.False(t, strings.Contains(buf.String(), mockSpanID))
 	buf.Reset()
 	l.WithDuration(time.Second).Infof(testlog)
-	assert.False(t, strings.Contains(buf.String(), mockTraceId))
-	assert.False(t, strings.Contains(buf.String(), mockSpanId))
+	assert.False(t, strings.Contains(buf.String(), mockTraceID))
+	assert.False(t, strings.Contains(buf.String(), mockSpanID))
 }
 
 type mockTrace struct{}
 
 func (t mockTrace) TraceId() string {
-	return mockTraceId
+	return mockTraceID
 }
 
 func (t mockTrace) SpanId() string {
-	return mockSpanId
+	return mockSpanID
 }
 
 func (t mockTrace) Finish() {