golint fixes for daemon/logger/*

 - downcase and privatize exported variables that were unused
 - make accurate an error message
 - added package comments
 - remove unused var ReadLogsNotSupported
 - enable linter
 - some spelling corrections

Signed-off-by: Morgan Bauer <mbauer@us.ibm.com>

daemon/logger/factory.go

@@ -8,13 +8,14 @@ import (
 	"time"
 )
 
-// Creator is a method that builds a logging driver instance with given context
+// Creator builds a logging driver instance with given context.
 type Creator func(Context) (Logger, error)
 
-//LogOptValidator is a method that validates the log opts provided
+// LogOptValidator checks the options specific to the underlying
+// logging implementation.
 type LogOptValidator func(cfg map[string]string) error
 
-// Context provides enough information for a logging driver to do its function
+// Context provides enough information for a logging driver to do its function.
 type Context struct {
 	Config              map[string]string
 	ContainerID         string
@@ -27,7 +28,7 @@ type Context struct {
 	LogPath             string
 }
 
-// Hostname returns the hostname from the underlying OS
+// Hostname returns the hostname from the underlying OS.
 func (ctx *Context) Hostname() (string, error) {
 	hostname, err := os.Hostname()
 	if err != nil {
@@ -36,7 +37,9 @@ func (ctx *Context) Hostname() (string, error) {
 	return hostname, nil
 }
 
-// Command returns the command that the container being logged was started with
+// Command returns the command that the container being logged was
+// started with. The Entrypoint is prepended to the container
+// arguments.
 func (ctx *Context) Command() string {
 	terms := []string{ctx.ContainerEntrypoint}
 	for _, arg := range ctx.ContainerArgs {
@@ -68,7 +71,7 @@ func (lf *logdriverFactory) registerLogOptValidator(name string, l LogOptValidat
 	defer lf.m.Unlock()
 
 	if _, ok := lf.optValidator[name]; ok {
-		return fmt.Errorf("logger: log driver named '%s' is already registered", name)
+		return fmt.Errorf("logger: log validator named '%s' is already registered", name)
 	}
 	lf.optValidator[name] = l
 	return nil
@@ -101,6 +104,8 @@ func RegisterLogDriver(name string, c Creator) error {
 	return factory.register(name, c)
 }
 
+// RegisterLogOptValidator registers the logging option validator with
+// the given logging driver name.
 func RegisterLogOptValidator(name string, l LogOptValidator) error {
 	return factory.registerLogOptValidator(name, l)
 }
@@ -110,6 +115,8 @@ func GetLogDriver(name string) (Creator, error) {
 	return factory.get(name)
 }
 
+// ValidateLogOpts checks the options for the given log driver. The
+// options supported are specific to the LogDriver implementation.
 func ValidateLogOpts(name string, cfg map[string]string) error {
 	l := factory.getLogOptValidator(name)
 	if l != nil {

daemon/logger/fluentd/fluentd.go

@@ -1,3 +1,5 @@
+// Package fluentd provides the log driver for forwarding server logs
+// to fluentd endpoints.
 package fluentd
 
 import (
@@ -14,14 +16,14 @@ import (
 	"github.com/fluent/fluent-logger-golang/fluent"
 )
 
-type Fluentd struct {
+type fluentd struct {
 	tag           string
 	containerID   string
 	containerName string
 	writer        *fluent.Fluent
 }
 
-type Receiver struct {
+type receiver struct {
 	ID     string
 	FullID string
 	Name   string
@@ -67,7 +69,7 @@ func parseConfig(ctx logger.Context) (string, int, string, error) {
 	}
 
 	if config["fluentd-tag"] != "" {
-		receiver := &Receiver{
+		receiver := &receiver{
 			ID:     ctx.ContainerID[:12],
 			FullID: ctx.ContainerID,
 			Name:   ctx.ContainerName,
@@ -86,6 +88,9 @@ func parseConfig(ctx logger.Context) (string, int, string, error) {
 	return host, port, tag, nil
 }
 
+// New creates a fluentd logger using the configuration passed in on
+// the context. Supported context configuration variables are
+// fluentd-address & fluentd-tag.
 func New(ctx logger.Context) (logger.Logger, error) {
 	host, port, tag, err := parseConfig(ctx)
 	if err != nil {
@@ -99,7 +104,7 @@ func New(ctx logger.Context) (logger.Logger, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &Fluentd{
+	return &fluentd{
 		tag:           tag,
 		containerID:   ctx.ContainerID,
 		containerName: ctx.ContainerName,
@@ -107,7 +112,7 @@ func New(ctx logger.Context) (logger.Logger, error) {
 	}, nil
 }
 
-func (f *Fluentd) Log(msg *logger.Message) error {
+func (f *fluentd) Log(msg *logger.Message) error {
 	data := map[string]string{
 		"container_id":   f.containerID,
 		"container_name": f.containerName,
@@ -119,6 +124,7 @@ func (f *Fluentd) Log(msg *logger.Message) error {
 	return f.writer.PostWithTime(f.tag, msg.Timestamp, data)
 }
 
+// ValidateLogOpt looks for fluentd specific log options fluentd-address & fluentd-tag.
 func ValidateLogOpt(cfg map[string]string) error {
 	for key := range cfg {
 		switch key {
@@ -131,10 +137,10 @@ func ValidateLogOpt(cfg map[string]string) error {
 	return nil
 }
 
-func (f *Fluentd) Close() error {
+func (f *fluentd) Close() error {
 	return f.writer.Close()
 }
 
-func (f *Fluentd) Name() string {
+func (f *fluentd) Name() string {
 	return name
 }

daemon/logger/gelf/gelf.go

@@ -1,5 +1,7 @@
 // +build linux
 
+// Package gelf provides the log driver for forwarding server logs to
+// endpoints that support the Graylog Extended Log Format.
 package gelf
 
 import (
@@ -17,17 +19,17 @@ import (
 
 const name = "gelf"
 
-type GelfLogger struct {
+type gelfLogger struct {
 	writer *gelf.Writer
 	ctx    logger.Context
-	fields GelfFields
+	fields gelfFields
 }
 
-type GelfFields struct {
+type gelfFields struct {
 	hostname      string
-	containerId   string
+	containerID   string
 	containerName string
-	imageId       string
+	imageID       string
 	imageName     string
 	command       string
 	tag           string
@@ -43,6 +45,9 @@ func init() {
 	}
 }
 
+// New creates a gelf logger using the configuration passed in on the
+// context. Supported context configuration variables are
+// gelf-address, & gelf-tag.
 func New(ctx logger.Context) (logger.Logger, error) {
 	// parse gelf address
 	address, err := parseAddress(ctx.Config["gelf-address"])
@@ -59,11 +64,11 @@ func New(ctx logger.Context) (logger.Logger, error) {
 	// remove trailing slash from container name
 	containerName := bytes.TrimLeft([]byte(ctx.ContainerName), "/")
 
-	fields := GelfFields{
+	fields := gelfFields{
 		hostname:      hostname,
-		containerId:   ctx.ContainerID,
+		containerID:   ctx.ContainerID,
 		containerName: string(containerName),
-		imageId:       ctx.ContainerImageID,
+		imageID:       ctx.ContainerImageID,
 		imageName:     ctx.ContainerImageName,
 		command:       ctx.Command(),
 		tag:           ctx.Config["gelf-tag"],
@@ -76,14 +81,14 @@ func New(ctx logger.Context) (logger.Logger, error) {
 		return nil, fmt.Errorf("gelf: cannot connect to GELF endpoint: %s %v", address, err)
 	}
 
-	return &GelfLogger{
+	return &gelfLogger{
 		writer: gelfWriter,
 		ctx:    ctx,
 		fields: fields,
 	}, nil
 }
 
-func (s *GelfLogger) Log(msg *logger.Message) error {
+func (s *gelfLogger) Log(msg *logger.Message) error {
 	// remove trailing and leading whitespace
 	short := bytes.TrimSpace([]byte(msg.Line))
 
@@ -99,9 +104,9 @@ func (s *GelfLogger) Log(msg *logger.Message) error {
 		TimeUnix: float64(msg.Timestamp.UnixNano()/int64(time.Millisecond)) / 1000.0,
 		Level:    level,
 		Extra: map[string]interface{}{
-			"_container_id":   s.fields.containerId,
+			"_container_id":   s.fields.containerID,
 			"_container_name": s.fields.containerName,
-			"_image_id":       s.fields.imageId,
+			"_image_id":       s.fields.imageID,
 			"_image_name":     s.fields.imageName,
 			"_command":        s.fields.command,
 			"_tag":            s.fields.tag,
@@ -115,14 +120,16 @@ func (s *GelfLogger) Log(msg *logger.Message) error {
 	return nil
 }
 
-func (s *GelfLogger) Close() error {
+func (s *gelfLogger) Close() error {
 	return s.writer.Close()
 }
 
-func (s *GelfLogger) Name() string {
+func (s *gelfLogger) Name() string {
 	return name
 }
 
+// ValidateLogOpt looks for gelf specific log options gelf-address, &
+// gelf-tag.
 func ValidateLogOpt(cfg map[string]string) error {
 	for key := range cfg {
 		switch key {

daemon/logger/journald/journald.go

@@ -1,5 +1,7 @@
 // +build linux
 
+// Package journald provides the log driver for forwarding server logs
+// to endpoints that receive the systemd format.
 package journald
 
 import (
@@ -12,7 +14,7 @@ import (
 
 const name = "journald"
 
-type Journald struct {
+type journald struct {
 	Jmap map[string]string
 }
 
@@ -22,6 +24,9 @@ func init() {
 	}
 }
 
+// New creates a journald logger using the configuration passed in on
+// the context. Supported context configuration variables are
+// syslog-address, syslog-facility, & syslog-tag.
 func New(ctx logger.Context) (logger.Logger, error) {
 	if !journal.Enabled() {
 		return nil, fmt.Errorf("journald is not enabled on this host")
@@ -36,20 +41,20 @@ func New(ctx logger.Context) (logger.Logger, error) {
 		"CONTAINER_ID":      ctx.ContainerID[:12],
 		"CONTAINER_ID_FULL": ctx.ContainerID,
 		"CONTAINER_NAME":    name}
-	return &Journald{Jmap: jmap}, nil
+	return &journald{Jmap: jmap}, nil
 }
 
-func (s *Journald) Log(msg *logger.Message) error {
+func (s *journald) Log(msg *logger.Message) error {
 	if msg.Source == "stderr" {
 		return journal.Send(string(msg.Line), journal.PriErr, s.Jmap)
 	}
 	return journal.Send(string(msg.Line), journal.PriInfo, s.Jmap)
 }
 
-func (s *Journald) Close() error {
+func (s *journald) Close() error {
 	return nil
 }
 
-func (s *Journald) Name() string {
+func (s *journald) Name() string {
 	return name
 }

daemon/logger/jsonfilelog/jsonfilelog.go

@@ -1,3 +1,6 @@
+// Package jsonfilelog provides the default Logger implementation for
+// Docker logging. This logger logs to files on the host server in the
+// JSON format.
 package jsonfilelog
 
 import (
@@ -23,12 +26,12 @@ import (
 )
 
 const (
+	// Name is the name of the file that the jsonlogger logs to.
 	Name               = "json-file"
 	maxJSONDecodeRetry = 10
 )
 
-// JSONFileLogger is Logger implementation for default docker logging:
-// JSON objects to file
+// JSONFileLogger is Logger implementation for default Docker logging.
 type JSONFileLogger struct {
 	buf          *bytes.Buffer
 	f            *os.File   // store for closing
@@ -49,7 +52,8 @@ func init() {
 	}
 }
 
-// New creates new JSONFileLogger which writes to filename
+// New creates new JSONFileLogger which writes to filename passed in
+// on given context.
 func New(ctx logger.Context) (logger.Logger, error) {
 	log, err := os.OpenFile(ctx.LogPath, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0600)
 	if err != nil {
@@ -63,14 +67,14 @@ func New(ctx logger.Context) (logger.Logger, error) {
 			return nil, err
 		}
 	}
-	var maxFiles int = 1
+	var maxFiles = 1
 	if maxFileString, ok := ctx.Config["max-file"]; ok {
 		maxFiles, err = strconv.Atoi(maxFileString)
 		if err != nil {
 			return nil, err
 		}
 		if maxFiles < 1 {
-			return nil, fmt.Errorf("max-files cannot be less than 1.")
+			return nil, fmt.Errorf("max-files cannot be less than 1")
 		}
 	}
 	return &JSONFileLogger{
@@ -84,7 +88,7 @@ func New(ctx logger.Context) (logger.Logger, error) {
 	}, nil
 }
 
-// Log converts logger.Message to jsonlog.JSONLog and serializes it to file
+// Log converts logger.Message to jsonlog.JSONLog and serializes it to file.
 func (l *JSONFileLogger) Log(msg *logger.Message) error {
 	l.mu.Lock()
 	defer l.mu.Unlock()
@@ -153,6 +157,7 @@ func rotate(name string, n int) error {
 	return nil
 }
 
+// backup renames a file from curr to old, creating an empty file curr if it does not exist.
 func backup(old, curr string) error {
 	if _, err := os.Stat(old); !os.IsNotExist(err) {
 		err := os.Remove(old)
@@ -170,6 +175,7 @@ func backup(old, curr string) error {
 	return os.Rename(curr, old)
 }
 
+// ValidateLogOpt looks for json specific log options max-file & max-size.
 func ValidateLogOpt(cfg map[string]string) error {
 	for key := range cfg {
 		switch key {
@@ -182,11 +188,12 @@ func ValidateLogOpt(cfg map[string]string) error {
 	return nil
 }
 
+// LogPath returns the location the given json logger logs to.
 func (l *JSONFileLogger) LogPath() string {
 	return l.ctx.LogPath
 }
 
-// Close closes underlying file and signals all readers to stop
+// Close closes underlying file and signals all readers to stop.
 func (l *JSONFileLogger) Close() error {
 	l.mu.Lock()
 	err := l.f.Close()
@@ -198,7 +205,7 @@ func (l *JSONFileLogger) Close() error {
 	return err
 }
 
-// Name returns name of this logger
+// Name returns name of this logger.
 func (l *JSONFileLogger) Name() string {
 	return Name
 }
@@ -216,7 +223,8 @@ func decodeLogLine(dec *json.Decoder, l *jsonlog.JSONLog) (*logger.Message, erro
 	return msg, nil
 }
 
-// Reads from the log file
+// ReadLogs implements the logger's LogReader interface for the logs
+// created by this driver.
 func (l *JSONFileLogger) ReadLogs(config logger.ReadConfig) *logger.LogWatcher {
 	logWatcher := logger.NewLogWatcher()
 
@@ -326,7 +334,7 @@ func followLogs(f *os.File, logWatcher *logger.LogWatcher, notifyRotate chan int
 				// try again because this shouldn't happen
 				if _, ok := err.(*json.SyntaxError); ok && retries <= maxJSONDecodeRetry {
 					dec = json.NewDecoder(f)
-					retries += 1
+					retries++
 					continue
 				}
 				logWatcher.Err <- err

daemon/logger/logger.go

@@ -1,3 +1,10 @@
+// Package logger defines interfaces that logger drivers implement to
+// log messages.
+//
+// The other half of a logger driver is the implementation of the
+// factory, which holds the contextual instance information that
+// allows multiple loggers of the same type to perform different
+// actions, such as logging to different locations.
 package logger
 
 import (
@@ -7,16 +14,16 @@ import (
 	"github.com/docker/docker/pkg/timeutils"
 )
 
-// ErrReadLogsNotSupported is returned when the logger does not support reading logs
+// ErrReadLogsNotSupported is returned when the logger does not support reading logs.
 var ErrReadLogsNotSupported = errors.New("configured logging reader does not support reading")
 
 const (
-	// TimeFormat is the time format used for timestamps sent to log readers
+	// TimeFormat is the time format used for timestamps sent to log readers.
 	TimeFormat           = timeutils.RFC3339NanoFixed
 	logWatcherBufferSize = 4096
 )
 
-// Message is datastructure that represents record from some container
+// Message is datastructure that represents record from some container.
 type Message struct {
 	ContainerID string
 	Line        []byte
@@ -24,31 +31,31 @@ type Message struct {
 	Timestamp   time.Time
 }
 
-// Logger is the interface for docker logging drivers
+// Logger is the interface for docker logging drivers.
 type Logger interface {
 	Log(*Message) error
 	Name() string
 	Close() error
 }
 
-// ReadConfig is the configuration passed into ReadLogs
+// ReadConfig is the configuration passed into ReadLogs.
 type ReadConfig struct {
 	Since  time.Time
 	Tail   int
 	Follow bool
 }
 
-// LogReader is the interface for reading log messages for loggers that support reading
+// LogReader is the interface for reading log messages for loggers that support reading.
 type LogReader interface {
 	// Read logs from underlying logging backend
 	ReadLogs(ReadConfig) *LogWatcher
 }
 
-// LogWatcher is used when consuming logs read from the LogReader interface
+// LogWatcher is used when consuming logs read from the LogReader interface.
 type LogWatcher struct {
-	// For sending log messages to a reader
+	// For sending log messages to a reader.
 	Msg chan *Message
-	// For sending error messages that occur while while reading logs
+	// For sending error messages that occur while while reading logs.
 	Err           chan error
 	closeNotifier chan struct{}
 }
@@ -62,13 +69,14 @@ func NewLogWatcher() *LogWatcher {
 	}
 }
 
-// Close notifies the underlying log reader to stop
+// Close notifies the underlying log reader to stop.
 func (w *LogWatcher) Close() {
 	close(w.closeNotifier)
 }
 
-// WatchClose returns a channel receiver that receives notification when the watcher has been closed
-// This should only be called from one goroutine
+// WatchClose returns a channel receiver that receives notification
+// when the watcher has been closed. This should only be called from
+// one goroutine.
 func (w *LogWatcher) WatchClose() <-chan struct{} {
 	return w.closeNotifier
 }

daemon/logger/syslog/syslog.go

@@ -1,5 +1,6 @@
 // +build linux
 
+// Package syslog provides the logdriver for forwarding server logs to syslog endpoints.
 package syslog
 
 import (
@@ -43,7 +44,7 @@ var facilities = map[string]syslog.Priority{
 	"local7":   syslog.LOG_LOCAL7,
 }
 
-type Syslog struct {
+type syslogger struct {
 	writer *syslog.Writer
 }
 
@@ -56,6 +57,9 @@ func init() {
 	}
 }
 
+// New creates a syslog logger using the configuration passed in on
+// the context. Supported context configuration variables are
+// syslog-address, syslog-facility, & syslog-tag.
 func New(ctx logger.Context) (logger.Logger, error) {
 	tag := ctx.Config["syslog-tag"]
 	if tag == "" {
@@ -82,23 +86,23 @@ func New(ctx logger.Context) (logger.Logger, error) {
 		return nil, err
 	}
 
-	return &Syslog{
+	return &syslogger{
 		writer: log,
 	}, nil
 }
 
-func (s *Syslog) Log(msg *logger.Message) error {
+func (s *syslogger) Log(msg *logger.Message) error {
 	if msg.Source == "stderr" {
 		return s.writer.Err(string(msg.Line))
 	}
 	return s.writer.Info(string(msg.Line))
 }
 
-func (s *Syslog) Close() error {
+func (s *syslogger) Close() error {
 	return s.writer.Close()
 }
 
-func (s *Syslog) Name() string {
+func (s *syslogger) Name() string {
 	return name
 }
 
@@ -132,12 +136,14 @@ func parseAddress(address string) (string, string, error) {
 	return "", "", nil
 }
 
+// ValidateLogOpt looks for syslog specific log options
+// syslog-address, syslog-facility, & syslog-tag.
 func ValidateLogOpt(cfg map[string]string) error {
 	for key := range cfg {
 		switch key {
 		case "syslog-address":
-		case "syslog-tag":
 		case "syslog-facility":
+		case "syslog-tag":
 		default:
 			return fmt.Errorf("unknown log opt '%s' for syslog log driver", key)
 		}

hack/make/validate-lint

@@ -22,6 +22,12 @@ packages=(
 	daemon/execdriver/native/template
 	daemon/graphdriver/aufs
 	daemon/graphdriver/devmapper
+	daemon/logger
+	daemon/logger/fluentd
+	daemon/logger/gelf
+	daemon/logger/journald
+	daemon/logger/jsonfilelog
+	daemon/logger/syslog
 	daemon/network
 	docker
 	dockerinit