// New creates a new etwLogs logger for the given container and registers the EWT provider.
func New(info logger.Info) (logger.Logger, error) {
	if err := registerETWProvider(); err != nil {
		return nil, err
	}
	logrus.Debugf("logging driver etwLogs configured for container: %s.", info.ContainerID)

	return &etwLogs{
		containerName: info.Name(),
		imageName:     info.ContainerImageName,
		containerID:   info.ContainerID,
		imageID:       info.ContainerImageID,
	}, nil
}

// New creates new JSONFileLogger which writes to filename passed in
// on given context.
func New(info logger.Info) (logger.Logger, error) {
	var capval int64 = -1
	if capacity, ok := info.Config["max-size"]; ok {
		var err error
		capval, err = units.FromHumanSize(capacity)
		if err != nil {
			return nil, err
		}
	}
	var maxFiles = 1
	if maxFileString, ok := info.Config["max-file"]; ok {
		var err error
		maxFiles, err = strconv.Atoi(maxFileString)
		if err != nil {
			return nil, err
		}
		if maxFiles < 1 {
			return nil, fmt.Errorf("max-file cannot be less than 1")
		}
	}

	writer, err := loggerutils.NewRotateFileWriter(info.LogPath, capval, maxFiles)
	if err != nil {
		return nil, err
	}

	var extra []byte
	if attrs := info.ExtraAttributes(nil); len(attrs) > 0 {
		var err error
		extra, err = json.Marshal(attrs)
		if err != nil {
			return nil, err
		}
	}

	return &JSONFileLogger{
		buf:     bytes.NewBuffer(nil),
		writer:  writer,
		readers: make(map[*logger.LogWatcher]struct{}),
		extra:   extra,
	}, nil
}

// New creates a journald logger using the configuration passed in on
// the context.
func New(info logger.Info) (logger.Logger, error) {
	if !journal.Enabled() {
		return nil, fmt.Errorf("journald is not enabled on this host")
	}

	// parse log tag
	tag, err := loggerutils.ParseLogTag(info, loggerutils.DefaultTemplate)
	if err != nil {
		return nil, err
	}

	vars := map[string]string{
		"CONTAINER_ID":      info.ContainerID[:12],
		"CONTAINER_ID_FULL": info.ContainerID,
		"CONTAINER_NAME":    info.Name(),
		"CONTAINER_TAG":     tag,
	}
	extraAttrs := info.ExtraAttributes(sanitizeKeyMod)
	for k, v := range extraAttrs {
		vars[k] = v
	}
	return &journald{vars: vars, readers: readerList{readers: make(map[*logger.LogWatcher]*logger.LogWatcher)}}, nil
}

// New creates splunk logger driver using configuration passed in context
func New(info logger.Info) (logger.Logger, error) {
	hostname, err := info.Hostname()
	if err != nil {
		return nil, fmt.Errorf("%s: cannot access hostname to set source field", driverName)
	}

	// Parse and validate Splunk URL
	splunkURL, err := parseURL(info)
	if err != nil {
		return nil, err
	}

	// Splunk Token is required parameter
	splunkToken, ok := info.Config[splunkTokenKey]
	if !ok {
		return nil, fmt.Errorf("%s: %s is expected", driverName, splunkTokenKey)
	}

	tlsConfig := &tls.Config{}

	// Splunk is using autogenerated certificates by default,
	// allow users to trust them with skipping verification
	if insecureSkipVerifyStr, ok := info.Config[splunkInsecureSkipVerifyKey]; ok {
		insecureSkipVerify, err := strconv.ParseBool(insecureSkipVerifyStr)
		if err != nil {
			return nil, err
		}
		tlsConfig.InsecureSkipVerify = insecureSkipVerify
	}

	// If path to the root certificate is provided - load it
	if caPath, ok := info.Config[splunkCAPathKey]; ok {
		caCert, err := ioutil.ReadFile(caPath)
		if err != nil {
			return nil, err
		}
		caPool := x509.NewCertPool()
		caPool.AppendCertsFromPEM(caCert)
		tlsConfig.RootCAs = caPool
	}

	if caName, ok := info.Config[splunkCANameKey]; ok {
		tlsConfig.ServerName = caName
	}

	gzipCompression := false
	if gzipCompressionStr, ok := info.Config[splunkGzipCompressionKey]; ok {
		gzipCompression, err = strconv.ParseBool(gzipCompressionStr)
		if err != nil {
			return nil, err
		}
	}

	gzipCompressionLevel := gzip.DefaultCompression
	if gzipCompressionLevelStr, ok := info.Config[splunkGzipCompressionLevelKey]; ok {
		var err error
		gzipCompressionLevel64, err := strconv.ParseInt(gzipCompressionLevelStr, 10, 32)
		if err != nil {
			return nil, err
		}
		gzipCompressionLevel = int(gzipCompressionLevel64)
		if gzipCompressionLevel < gzip.DefaultCompression || gzipCompressionLevel > gzip.BestCompression {
			err := fmt.Errorf("Not supported level '%s' for %s (supported values between %d and %d).",
				gzipCompressionLevelStr, splunkGzipCompressionLevelKey, gzip.DefaultCompression, gzip.BestCompression)
			return nil, err
		}
	}

	transport := &http.Transport{
		TLSClientConfig: tlsConfig,
	}
	client := &http.Client{
		Transport: transport,
	}

	source := info.Config[splunkSourceKey]
	sourceType := info.Config[splunkSourceTypeKey]
	index := info.Config[splunkIndexKey]

	var nullMessage = &splunkMessage{
		Host:       hostname,
		Source:     source,
		SourceType: sourceType,
		Index:      index,
	}

	// Allow user to remove tag from the messages by setting tag to empty string
	tag := ""
	if tagTemplate, ok := info.Config[tagKey]; !ok || tagTemplate != "" {
		tag, err = loggerutils.ParseLogTag(info, loggerutils.DefaultTemplate)
		if err != nil {
			return nil, err
		}
	}

	attrs := info.ExtraAttributes(nil)

	var (
		postMessagesFrequency = getAdvancedOptionDuration(envVarPostMessagesFrequency, defaultPostMessagesFrequency)
//.........这里部分代码省略.........

// New creates a gelf logger using the configuration passed in on the
// context. The supported context configuration variable is gelf-address.
func New(info logger.Info) (logger.Logger, error) {
	// parse gelf address
	address, err := parseAddress(info.Config["gelf-address"])
	if err != nil {
		return nil, err
	}

	// collect extra data for GELF message
	hostname, err := info.Hostname()
	if err != nil {
		return nil, fmt.Errorf("gelf: cannot access hostname to set source field")
	}

	// parse log tag
	tag, err := loggerutils.ParseLogTag(info, loggerutils.DefaultTemplate)
	if err != nil {
		return nil, err
	}

	extra := map[string]interface{}{
		"_container_id":   info.ContainerID,
		"_container_name": info.Name(),
		"_image_id":       info.ContainerImageID,
		"_image_name":     info.ContainerImageName,
		"_command":        info.Command(),
		"_tag":            tag,
		"_created":        info.ContainerCreated,
	}

	extraAttrs := info.ExtraAttributes(func(key string) string {
		if key[0] == '_' {
			return key
		}
		return "_" + key
	})
	for k, v := range extraAttrs {
		extra[k] = v
	}

	rawExtra, err := json.Marshal(extra)
	if err != nil {
		return nil, err
	}

	// create new gelfWriter
	gelfWriter, err := gelf.NewWriter(address)
	if err != nil {
		return nil, fmt.Errorf("gelf: cannot connect to GELF endpoint: %s %v", address, err)
	}

	if v, ok := info.Config["gelf-compression-type"]; ok {
		switch v {
		case "gzip":
			gelfWriter.CompressionType = gelf.CompressGzip
		case "zlib":
			gelfWriter.CompressionType = gelf.CompressZlib
		case "none":
			gelfWriter.CompressionType = gelf.CompressNone
		default:
			return nil, fmt.Errorf("gelf: invalid compression type %q", v)
		}
	}

	if v, ok := info.Config["gelf-compression-level"]; ok {
		val, err := strconv.Atoi(v)
		if err != nil {
			return nil, fmt.Errorf("gelf: invalid compression level %s, err %v", v, err)
		}
		gelfWriter.CompressionLevel = val
	}

	return &gelfLogger{
		writer:   gelfWriter,
		info:     info,
		hostname: hostname,
		rawExtra: rawExtra,
	}, nil
}

// Test default settings
func TestDefault(t *testing.T) {
	hec := NewHTTPEventCollectorMock(t)

	go hec.Serve()

	info := logger.Info{
		Config: map[string]string{
			splunkURLKey:   hec.URL(),
			splunkTokenKey: hec.token,
		},
		ContainerID:        "containeriid",
		ContainerName:      "container_name",
		ContainerImageID:   "contaimageid",
		ContainerImageName: "container_image_name",
	}

	hostname, err := info.Hostname()
	if err != nil {
		t.Fatal(err)
	}

	loggerDriver, err := New(info)
	if err != nil {
		t.Fatal(err)
	}

	if loggerDriver.Name() != driverName {
		t.Fatal("Unexpected logger driver name")
	}

	if !hec.connectionVerified {
		t.Fatal("By default connection should be verified")
	}

	splunkLoggerDriver, ok := loggerDriver.(*splunkLoggerInline)
	if !ok {
		t.Fatal("Unexpected Splunk Logging Driver type")
	}

	if splunkLoggerDriver.url != hec.URL()+"/services/collector/event/1.0" ||
		splunkLoggerDriver.auth != "Splunk "+hec.token ||
		splunkLoggerDriver.nullMessage.Host != hostname ||
		splunkLoggerDriver.nullMessage.Source != "" ||
		splunkLoggerDriver.nullMessage.SourceType != "" ||
		splunkLoggerDriver.nullMessage.Index != "" ||
		splunkLoggerDriver.gzipCompression != false ||
		splunkLoggerDriver.postMessagesFrequency != defaultPostMessagesFrequency ||
		splunkLoggerDriver.postMessagesBatchSize != defaultPostMessagesBatchSize ||
		splunkLoggerDriver.bufferMaximum != defaultBufferMaximum ||
		cap(splunkLoggerDriver.stream) != defaultStreamChannelSize {
		t.Fatal("Found not default values setup in Splunk Logging Driver.")
	}

	message1Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("{\"a\":\"b\"}"), "stdout", message1Time, nil, false}); err != nil {
		t.Fatal(err)
	}
	message2Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("notajson"), "stdout", message2Time, nil, false}); err != nil {
		t.Fatal(err)
	}

	err = loggerDriver.Close()
	if err != nil {
		t.Fatal(err)
	}

	if len(hec.messages) != 2 {
		t.Fatal("Expected two messages")
	}

	if *hec.gzipEnabled {
		t.Fatal("Gzip should not be used")
	}

	message1 := hec.messages[0]
	if message1.Time != fmt.Sprintf("%f", float64(message1Time.UnixNano())/float64(time.Second)) ||
		message1.Host != hostname ||
		message1.Source != "" ||
		message1.SourceType != "" ||
		message1.Index != "" {
		t.Fatalf("Unexpected values of message 1 %v", message1)
	}

	if event, err := message1.EventAsMap(); err != nil {
		t.Fatal(err)
	} else {
		if event["line"] != "{\"a\":\"b\"}" ||
			event["source"] != "stdout" ||
			event["tag"] != "containeriid" ||
			len(event) != 3 {
			t.Fatalf("Unexpected event in message %v", event)
		}
	}

	message2 := hec.messages[1]
	if message2.Time != fmt.Sprintf("%f", float64(message2Time.UnixNano())/float64(time.Second)) ||
		message2.Host != hostname ||
		message2.Source != "" ||
//.........这里部分代码省略.........

// Verify that Splunk Logging Driver can accept tag="" which will allow to send raw messages
// in the same way we get them in stdout/stderr
func TestRawFormatWithoutTag(t *testing.T) {
	hec := NewHTTPEventCollectorMock(t)

	go hec.Serve()

	info := logger.Info{
		Config: map[string]string{
			splunkURLKey:    hec.URL(),
			splunkTokenKey:  hec.token,
			splunkFormatKey: splunkFormatRaw,
			tagKey:          "",
		},
		ContainerID:        "containeriid",
		ContainerName:      "/container_name",
		ContainerImageID:   "contaimageid",
		ContainerImageName: "container_image_name",
	}

	hostname, err := info.Hostname()
	if err != nil {
		t.Fatal(err)
	}

	loggerDriver, err := New(info)
	if err != nil {
		t.Fatal(err)
	}

	if !hec.connectionVerified {
		t.Fatal("By default connection should be verified")
	}

	splunkLoggerDriver, ok := loggerDriver.(*splunkLoggerRaw)
	if !ok {
		t.Fatal("Unexpected Splunk Logging Driver type")
	}

	if splunkLoggerDriver.url != hec.URL()+"/services/collector/event/1.0" ||
		splunkLoggerDriver.auth != "Splunk "+hec.token ||
		splunkLoggerDriver.nullMessage.Host != hostname ||
		splunkLoggerDriver.nullMessage.Source != "" ||
		splunkLoggerDriver.nullMessage.SourceType != "" ||
		splunkLoggerDriver.nullMessage.Index != "" ||
		splunkLoggerDriver.gzipCompression != false ||
		splunkLoggerDriver.postMessagesFrequency != defaultPostMessagesFrequency ||
		splunkLoggerDriver.postMessagesBatchSize != defaultPostMessagesBatchSize ||
		splunkLoggerDriver.bufferMaximum != defaultBufferMaximum ||
		cap(splunkLoggerDriver.stream) != defaultStreamChannelSize ||
		string(splunkLoggerDriver.prefix) != "" {
		t.Log(string(splunkLoggerDriver.prefix) + "a")
		t.Fatal("Values do not match configuration.")
	}

	message1Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("{\"a\":\"b\"}"), "stdout", message1Time, nil, false}); err != nil {
		t.Fatal(err)
	}
	message2Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("notjson"), "stdout", message2Time, nil, false}); err != nil {
		t.Fatal(err)
	}

	err = loggerDriver.Close()
	if err != nil {
		t.Fatal(err)
	}

	if len(hec.messages) != 2 {
		t.Fatal("Expected two messages")
	}

	message1 := hec.messages[0]
	if message1.Time != fmt.Sprintf("%f", float64(message1Time.UnixNano())/float64(time.Second)) ||
		message1.Host != hostname ||
		message1.Source != "" ||
		message1.SourceType != "" ||
		message1.Index != "" {
		t.Fatalf("Unexpected values of message 1 %v", message1)
	}

	if event, err := message1.EventAsString(); err != nil {
		t.Fatal(err)
	} else {
		if event != "{\"a\":\"b\"}" {
			t.Fatalf("Unexpected event in message 1 %v", event)
		}
	}

	message2 := hec.messages[1]
	if message2.Time != fmt.Sprintf("%f", float64(message2Time.UnixNano())/float64(time.Second)) ||
		message2.Host != hostname ||
		message2.Source != "" ||
		message2.SourceType != "" ||
		message2.Index != "" {
		t.Fatalf("Unexpected values of message 2 %v", message2)
	}

	if event, err := message2.EventAsString(); err != nil {
//.........这里部分代码省略.........

// Verify JSON format
func TestJsonFormat(t *testing.T) {
	hec := NewHTTPEventCollectorMock(t)

	go hec.Serve()

	info := logger.Info{
		Config: map[string]string{
			splunkURLKey:                  hec.URL(),
			splunkTokenKey:                hec.token,
			splunkFormatKey:               splunkFormatJSON,
			splunkGzipCompressionKey:      "true",
			splunkGzipCompressionLevelKey: "1",
		},
		ContainerID:        "containeriid",
		ContainerName:      "/container_name",
		ContainerImageID:   "contaimageid",
		ContainerImageName: "container_image_name",
	}

	hostname, err := info.Hostname()
	if err != nil {
		t.Fatal(err)
	}

	loggerDriver, err := New(info)
	if err != nil {
		t.Fatal(err)
	}

	if !hec.connectionVerified {
		t.Fatal("By default connection should be verified")
	}

	splunkLoggerDriver, ok := loggerDriver.(*splunkLoggerJSON)
	if !ok {
		t.Fatal("Unexpected Splunk Logging Driver type")
	}

	if splunkLoggerDriver.url != hec.URL()+"/services/collector/event/1.0" ||
		splunkLoggerDriver.auth != "Splunk "+hec.token ||
		splunkLoggerDriver.nullMessage.Host != hostname ||
		splunkLoggerDriver.nullMessage.Source != "" ||
		splunkLoggerDriver.nullMessage.SourceType != "" ||
		splunkLoggerDriver.nullMessage.Index != "" ||
		splunkLoggerDriver.gzipCompression != true ||
		splunkLoggerDriver.gzipCompressionLevel != gzip.BestSpeed ||
		splunkLoggerDriver.postMessagesFrequency != defaultPostMessagesFrequency ||
		splunkLoggerDriver.postMessagesBatchSize != defaultPostMessagesBatchSize ||
		splunkLoggerDriver.bufferMaximum != defaultBufferMaximum ||
		cap(splunkLoggerDriver.stream) != defaultStreamChannelSize {
		t.Fatal("Values do not match configuration.")
	}

	message1Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("{\"a\":\"b\"}"), "stdout", message1Time, nil, false}); err != nil {
		t.Fatal(err)
	}
	message2Time := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("notjson"), "stdout", message2Time, nil, false}); err != nil {
		t.Fatal(err)
	}

	err = loggerDriver.Close()
	if err != nil {
		t.Fatal(err)
	}

	if len(hec.messages) != 2 {
		t.Fatal("Expected two messages")
	}

	message1 := hec.messages[0]
	if message1.Time != fmt.Sprintf("%f", float64(message1Time.UnixNano())/float64(time.Second)) ||
		message1.Host != hostname ||
		message1.Source != "" ||
		message1.SourceType != "" ||
		message1.Index != "" {
		t.Fatalf("Unexpected values of message 1 %v", message1)
	}

	if event, err := message1.EventAsMap(); err != nil {
		t.Fatal(err)
	} else {
		if event["line"].(map[string]interface{})["a"] != "b" ||
			event["source"] != "stdout" ||
			event["tag"] != "containeriid" ||
			len(event) != 3 {
			t.Fatalf("Unexpected event in message 1 %v", event)
		}
	}

	message2 := hec.messages[1]
	if message2.Time != fmt.Sprintf("%f", float64(message2Time.UnixNano())/float64(time.Second)) ||
		message2.Host != hostname ||
		message2.Source != "" ||
		message2.SourceType != "" ||
		message2.Index != "" {
		t.Fatalf("Unexpected values of message 2 %v", message2)
	}
//.........这里部分代码省略.........

// Verify inline format with a not default settings for most of options
func TestInlineFormatWithNonDefaultOptions(t *testing.T) {
	hec := NewHTTPEventCollectorMock(t)

	go hec.Serve()

	info := logger.Info{
		Config: map[string]string{
			splunkURLKey:             hec.URL(),
			splunkTokenKey:           hec.token,
			splunkSourceKey:          "mysource",
			splunkSourceTypeKey:      "mysourcetype",
			splunkIndexKey:           "myindex",
			splunkFormatKey:          splunkFormatInline,
			splunkGzipCompressionKey: "true",
			tagKey:    "{{.ImageName}}/{{.Name}}",
			labelsKey: "a",
		},
		ContainerID:        "containeriid",
		ContainerName:      "/container_name",
		ContainerImageID:   "contaimageid",
		ContainerImageName: "container_image_name",
		ContainerLabels: map[string]string{
			"a": "b",
		},
	}

	hostname, err := info.Hostname()
	if err != nil {
		t.Fatal(err)
	}

	loggerDriver, err := New(info)
	if err != nil {
		t.Fatal(err)
	}

	if !hec.connectionVerified {
		t.Fatal("By default connection should be verified")
	}

	splunkLoggerDriver, ok := loggerDriver.(*splunkLoggerInline)
	if !ok {
		t.Fatal("Unexpected Splunk Logging Driver type")
	}

	if splunkLoggerDriver.url != hec.URL()+"/services/collector/event/1.0" ||
		splunkLoggerDriver.auth != "Splunk "+hec.token ||
		splunkLoggerDriver.nullMessage.Host != hostname ||
		splunkLoggerDriver.nullMessage.Source != "mysource" ||
		splunkLoggerDriver.nullMessage.SourceType != "mysourcetype" ||
		splunkLoggerDriver.nullMessage.Index != "myindex" ||
		splunkLoggerDriver.gzipCompression != true ||
		splunkLoggerDriver.gzipCompressionLevel != gzip.DefaultCompression ||
		splunkLoggerDriver.postMessagesFrequency != defaultPostMessagesFrequency ||
		splunkLoggerDriver.postMessagesBatchSize != defaultPostMessagesBatchSize ||
		splunkLoggerDriver.bufferMaximum != defaultBufferMaximum ||
		cap(splunkLoggerDriver.stream) != defaultStreamChannelSize {
		t.Fatal("Values do not match configuration.")
	}

	messageTime := time.Now()
	if err := loggerDriver.Log(&logger.Message{[]byte("1"), "stdout", messageTime, nil, false}); err != nil {
		t.Fatal(err)
	}

	err = loggerDriver.Close()
	if err != nil {
		t.Fatal(err)
	}

	if len(hec.messages) != 1 {
		t.Fatal("Expected one message")
	}

	if !*hec.gzipEnabled {
		t.Fatal("Gzip should be used")
	}

	message := hec.messages[0]
	if message.Time != fmt.Sprintf("%f", float64(messageTime.UnixNano())/float64(time.Second)) ||
		message.Host != hostname ||
		message.Source != "mysource" ||
		message.SourceType != "mysourcetype" ||
		message.Index != "myindex" {
		t.Fatalf("Unexpected values of message %v", message)
	}

	if event, err := message.EventAsMap(); err != nil {
		t.Fatal(err)
	} else {
		if event["line"] != "1" ||
			event["source"] != "stdout" ||
			event["tag"] != "container_image_name/container_name" ||
			event["attrs"].(map[string]interface{})["a"] != "b" ||
			len(event) != 4 {
			t.Fatalf("Unexpected event in message %v", event)
		}
	}

//.........这里部分代码省略.........

// New creates a fluentd logger using the configuration passed in on
// the context. The supported context configuration variable is
// fluentd-address.
func New(info logger.Info) (logger.Logger, error) {
	loc, err := parseAddress(info.Config[addressKey])
	if err != nil {
		return nil, err
	}

	tag, err := loggerutils.ParseLogTag(info, loggerutils.DefaultTemplate)
	if err != nil {
		return nil, err
	}

	extra := info.ExtraAttributes(nil)

	bufferLimit := defaultBufferLimit
	if info.Config[bufferLimitKey] != "" {
		bl64, err := units.RAMInBytes(info.Config[bufferLimitKey])
		if err != nil {
			return nil, err
		}
		bufferLimit = int(bl64)
	}

	retryWait := defaultRetryWait
	if info.Config[retryWaitKey] != "" {
		rwd, err := time.ParseDuration(info.Config[retryWaitKey])
		if err != nil {
			return nil, err
		}
		retryWait = int(rwd.Seconds() * 1000)
	}

	maxRetries := defaultMaxRetries
	if info.Config[maxRetriesKey] != "" {
		mr64, err := strconv.ParseUint(info.Config[maxRetriesKey], 10, strconv.IntSize)
		if err != nil {
			return nil, err
		}
		maxRetries = int(mr64)
	}

	asyncConnect := false
	if info.Config[asyncConnectKey] != "" {
		if asyncConnect, err = strconv.ParseBool(info.Config[asyncConnectKey]); err != nil {
			return nil, err
		}
	}

	fluentConfig := fluent.Config{
		FluentPort:       loc.port,
		FluentHost:       loc.host,
		FluentNetwork:    loc.protocol,
		FluentSocketPath: loc.path,
		BufferLimit:      bufferLimit,
		RetryWait:        retryWait,
		MaxRetry:         maxRetries,
		AsyncConnect:     asyncConnect,
	}

	logrus.WithField("container", info.ContainerID).WithField("config", fluentConfig).
		Debug("logging driver fluentd configured")

	log, err := fluent.New(fluentConfig)
	if err != nil {
		return nil, err
	}
	return &fluentd{
		tag:           tag,
		containerID:   info.ContainerID,
		containerName: info.ContainerName,
		writer:        log,
		extra:         extra,
	}, nil
}

// New creates a new logger that logs to Google Cloud Logging using the application
// default credentials.
//
// See https://developers.google.com/identity/protocols/application-default-credentials
func New(info logger.Info) (logger.Logger, error) {
	initGCP()

	var project string
	if projectID != "" {
		project = projectID
	}
	if projectID, found := info.Config[projectOptKey]; found {
		project = projectID
	}
	if project == "" {
		return nil, fmt.Errorf("No project was specified and couldn't read project from the meatadata server. Please specify a project")
	}

	// Issue #29344: gcplogs segfaults (static binary)
	// If HOME is not set, logging.NewClient() will call os/user.Current() via oauth2/google.
	// However, in static binary, os/user.Current() leads to segfault due to a glibc issue that won't be fixed
	// in a short term. (golang/go#13470, https://sourceware.org/bugzilla/show_bug.cgi?id=19341)
	// So we forcibly set HOME so as to avoid call to os/user/Current()
	if err := ensureHomeIfIAmStatic(); err != nil {
		return nil, err
	}

	c, err := logging.NewClient(context.Background(), project)
	if err != nil {
		return nil, err
	}
	lg := c.Logger("gcplogs-docker-driver")

	if err := c.Ping(context.Background()); err != nil {
		return nil, fmt.Errorf("unable to connect or authenticate with Google Cloud Logging: %v", err)
	}

	l := &gcplogs{
		logger: lg,
		container: &containerInfo{
			Name:      info.ContainerName,
			ID:        info.ContainerID,
			ImageName: info.ContainerImageName,
			ImageID:   info.ContainerImageID,
			Created:   info.ContainerCreated,
			Metadata:  info.ExtraAttributes(nil),
		},
	}

	if info.Config[logCmdKey] == "true" {
		l.container.Command = info.Command()
	}

	if onGCE {
		l.instance = &instanceInfo{
			Zone: zone,
			Name: instanceName,
			ID:   instanceID,
		}
	} else if info.Config[logZoneKey] != "" || info.Config[logNameKey] != "" || info.Config[logIDKey] != "" {
		l.instance = &instanceInfo{
			Zone: info.Config[logZoneKey],
			Name: info.Config[logNameKey],
			ID:   info.Config[logIDKey],
		}
	}

	// The logger "overflows" at a rate of 10,000 logs per second and this
	// overflow func is called. We want to surface the error to the user
	// without overly spamming /var/log/docker.log so we log the first time
	// we overflow and every 1000th time after.
	c.OnError = func(err error) {
		if err == logging.ErrOverflow {
			if i := atomic.AddUint64(&droppedLogs, 1); i%1000 == 1 {
				logrus.Errorf("gcplogs driver has dropped %v logs", i)
			}
		} else {
			logrus.Error(err)
		}
	}

	return l, nil
}