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minio/cmd/event-notifier.go

829 lines
24 KiB

/*
* Minio Cloud Storage, (C) 2016, 2017 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"bytes"
"encoding/json"
"encoding/xml"
"fmt"
"net"
"net/url"
"path"
"sync"
"github.com/Sirupsen/logrus"
)
const (
minioEventSource = "minio:s3"
)
type externalNotifier struct {
// Per-bucket notification config. This is updated via
// PutBucketNotification API.
notificationConfigs map[string]*notificationConfig
// An external target keeps a connection to an external
// service to which events are to be sent. It is a mapping
// from an ARN to a log object
targets map[string]*logrus.Logger
rwMutex *sync.RWMutex
}
type internalNotifier struct {
// per-bucket listener configuration. This is updated
// when listeners connect or disconnect.
listenerConfigs map[string][]listenerConfig
// An internal target is a peer Minio server, that is
// connected to a listening client. Here, targets is a map of
// listener ARN to log object.
targets map[string]*listenerLogger
// Connected listeners is a map of listener ARNs to channels
// on which the ListenBucket API handler go routine is waiting
// for events to send to a client.
connectedListeners map[string]chan []NotificationEvent
rwMutex *sync.RWMutex
}
// Global event notification configuration. This structure has state
// about configured external notifications, and run-time configuration
// for listener notifications.
type eventNotifier struct {
// `external` here refers to notification configuration to
// send events to supported external systems
external externalNotifier
// `internal` refers to notification configuration for live
// listening clients. Events for a client are send from all
// servers, internally to a particular server that is
// connected to the client.
internal internalNotifier
}
// Represents data to be sent with notification event.
type eventData struct {
Type EventName
Bucket string
ObjInfo ObjectInfo
ReqParams map[string]string
Host string
Port string
UserAgent string
}
// New notification event constructs a new notification event message from
// input request metadata which completed successfully.
func newNotificationEvent(event eventData) NotificationEvent {
getResponseOriginEndpointKey := func() string {
host := globalMinioHost
if host == "" {
// FIXME: Send FQDN or hostname of this machine than sending IP address.
host = localIP4.ToSlice()[0]
}
return fmt.Sprintf("%s://%s:%s", getURLScheme(globalIsSSL), host, globalMinioPort)
}
// Fetch the region.
region := serverConfig.GetRegion()
// Fetch the credentials.
creds := serverConfig.GetCredential()
// Time when Minio finished processing the request.
eventTime := UTCNow()
// Fetch a hexadecimal representation of event time in nano seconds.
uniqueID := mustGetRequestID(eventTime)
/// Construct a new object created event.
// Following blocks fills in all the necessary details of s3
// event message structure.
// http://docs.aws.amazon.com/AmazonS3/latest/dev/notification-content-structure.html
nEvent := NotificationEvent{
EventVersion: eventVersion,
EventSource: minioEventSource,
AwsRegion: region,
EventTime: eventTime.Format(timeFormatAMZ),
EventName: event.Type.String(),
UserIdentity: identity{creds.AccessKey},
RequestParameters: event.ReqParams,
ResponseElements: map[string]string{
responseRequestIDKey: uniqueID,
// Following is a custom response element to indicate
// event origin server endpoint.
responseOriginEndpointKey: getResponseOriginEndpointKey(),
},
S3: eventMeta{
SchemaVersion: eventSchemaVersion,
ConfigurationID: eventConfigID,
Bucket: bucketMeta{
Name: event.Bucket,
OwnerIdentity: identity{creds.AccessKey},
ARN: bucketARNPrefix + event.Bucket,
},
},
Source: sourceInfo{
Host: event.Host,
Port: event.Port,
UserAgent: event.UserAgent,
},
}
// Escape the object name. For example "red flower.jpg" becomes "red+flower.jpg".
escapedObj := url.QueryEscape(event.ObjInfo.Name)
// For delete object event type, we do not need to set ETag and Size.
if event.Type == ObjectRemovedDelete {
nEvent.S3.Object = objectMeta{
Key: escapedObj,
VersionID: "1",
Sequencer: uniqueID,
}
return nEvent
}
// For all other events we should set ETag and Size.
nEvent.S3.Object = objectMeta{
Key: escapedObj,
ETag: event.ObjInfo.ETag,
Size: event.ObjInfo.Size,
ContentType: event.ObjInfo.ContentType,
UserDefined: event.ObjInfo.UserDefined,
VersionID: "1",
Sequencer: uniqueID,
}
// Success.
return nEvent
}
// Fetch all external targets. This returns a copy of the current map of
// external notification targets.
func (en eventNotifier) GetAllExternalTargets() map[string]*logrus.Logger {
en.external.rwMutex.RLock()
defer en.external.rwMutex.RUnlock()
targetsCopy := make(map[string]*logrus.Logger)
for k, v := range en.external.targets {
targetsCopy[k] = v
}
return targetsCopy
}
// Fetch the external target.
func (en eventNotifier) GetExternalTarget(queueARN string) *logrus.Logger {
en.external.rwMutex.RLock()
defer en.external.rwMutex.RUnlock()
return en.external.targets[queueARN]
}
func (en eventNotifier) GetInternalTarget(arn string) *listenerLogger {
en.internal.rwMutex.RLock()
defer en.internal.rwMutex.RUnlock()
return en.internal.targets[arn]
}
// Set a new sns target for an input sns ARN.
func (en *eventNotifier) AddListenerChan(snsARN string, listenerCh chan []NotificationEvent) error {
if listenerCh == nil {
return errInvalidArgument
}
en.internal.rwMutex.Lock()
defer en.internal.rwMutex.Unlock()
en.internal.connectedListeners[snsARN] = listenerCh
return nil
}
// Remove sns target for an input sns ARN.
func (en *eventNotifier) RemoveListenerChan(snsARN string) {
en.internal.rwMutex.Lock()
defer en.internal.rwMutex.Unlock()
if en.internal.connectedListeners != nil {
delete(en.internal.connectedListeners, snsARN)
}
}
func (en *eventNotifier) SendListenerEvent(arn string, event []NotificationEvent) error {
en.internal.rwMutex.Lock()
defer en.internal.rwMutex.Unlock()
ch, ok := en.internal.connectedListeners[arn]
if ok {
ch <- event
}
// If the channel is not present we ignore the event.
return nil
}
// Fetch bucket notification config for an input bucket.
func (en eventNotifier) GetBucketNotificationConfig(bucket string) *notificationConfig {
en.external.rwMutex.RLock()
defer en.external.rwMutex.RUnlock()
return en.external.notificationConfigs[bucket]
}
func (en *eventNotifier) SetBucketNotificationConfig(bucket string, ncfg *notificationConfig) {
en.external.rwMutex.Lock()
if ncfg == nil {
delete(en.external.notificationConfigs, bucket)
} else {
en.external.notificationConfigs[bucket] = ncfg
}
en.external.rwMutex.Unlock()
}
func (en *eventNotifier) GetBucketListenerConfig(bucket string) []listenerConfig {
en.internal.rwMutex.RLock()
defer en.internal.rwMutex.RUnlock()
return en.internal.listenerConfigs[bucket]
}
func (en *eventNotifier) SetBucketListenerConfig(bucket string, lcfg []listenerConfig) error {
en.internal.rwMutex.Lock()
defer en.internal.rwMutex.Unlock()
if len(lcfg) == 0 {
delete(en.internal.listenerConfigs, bucket)
} else {
en.internal.listenerConfigs[bucket] = lcfg
}
for _, elcArr := range en.internal.listenerConfigs {
for _, elcElem := range elcArr {
currArn := elcElem.TopicConfig.TopicARN
logger, err := newListenerLogger(currArn, elcElem.TargetServer)
if err != nil {
return err
}
en.internal.targets[currArn] = logger
}
}
return nil
}
func eventNotifyForBucketNotifications(eventType, objectName, bucketName string, nEvent []NotificationEvent) {
nConfig := globalEventNotifier.GetBucketNotificationConfig(bucketName)
if nConfig == nil {
return
}
// Validate if the event and object match the queue configs.
for _, qConfig := range nConfig.QueueConfigs {
eventMatch := eventMatch(eventType, qConfig.Events)
ruleMatch := filterRuleMatch(objectName, qConfig.Filter.Key.FilterRules)
if eventMatch && ruleMatch {
targetLog := globalEventNotifier.GetExternalTarget(qConfig.QueueARN)
if targetLog != nil {
targetLog.WithFields(logrus.Fields{
"Key": path.Join(bucketName, objectName),
"EventType": eventType,
"Records": nEvent,
}).Info()
}
}
}
}
func eventNotifyForBucketListeners(eventType, objectName, bucketName string,
nEvent []NotificationEvent) {
lCfgs := globalEventNotifier.GetBucketListenerConfig(bucketName)
if lCfgs == nil {
return
}
// Validate if the event and object match listener configs
for _, lcfg := range lCfgs {
ruleMatch := filterRuleMatch(objectName, lcfg.TopicConfig.Filter.Key.FilterRules)
eventMatch := eventMatch(eventType, lcfg.TopicConfig.Events)
if eventMatch && ruleMatch {
targetLog := globalEventNotifier.GetInternalTarget(
lcfg.TopicConfig.TopicARN)
if targetLog != nil && targetLog.log != nil {
targetLog.log.WithFields(logrus.Fields{
"Key": path.Join(bucketName, objectName),
"EventType": eventType,
"Records": nEvent,
}).Info()
}
}
}
}
// eventNotify notifies an event to relevant targets based on their
// bucket configuration (notifications and listeners).
func eventNotify(event eventData) {
if globalEventNotifier == nil {
return
}
// Notifies a new event.
// List of events reported through this function are
// - s3:ObjectCreated:Put
// - s3:ObjectCreated:Post
// - s3:ObjectCreated:Copy
// - s3:ObjectCreated:CompleteMultipartUpload
// - s3:ObjectRemoved:Delete
// Event type.
eventType := event.Type.String()
// Object name.
objectName := event.ObjInfo.Name
// Save the notification event to be sent.
notificationEvent := []NotificationEvent{newNotificationEvent(event)}
// Notify external targets.
eventNotifyForBucketNotifications(eventType, objectName, event.Bucket, notificationEvent)
// Notify internal targets.
eventNotifyForBucketListeners(eventType, objectName, event.Bucket, notificationEvent)
}
// loads notification config if any for a given bucket, returns
// structured notification config.
func loadNotificationConfig(bucket string, objAPI ObjectLayer) (*notificationConfig, error) {
// Construct the notification config path.
ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
if err := objLock.GetRLock(globalOperationTimeout); err != nil {
return nil, err
}
defer objLock.RUnlock()
var buffer bytes.Buffer
err := objAPI.GetObject(minioMetaBucket, ncPath, 0, -1, &buffer) // Read everything.
if err != nil {
// 'notification.xml' not found return
// 'errNoSuchNotifications'. This is default when no
// bucket notifications are found on the bucket.
if isErrObjectNotFound(err) || isErrIncompleteBody(err) {
return nil, traceError(errNoSuchNotifications)
}
errorIf(err, "Unable to load bucket-notification for bucket %s", bucket)
// Returns error for other errors.
return nil, err
}
// if `notifications.xml` is empty we should return NoSuchNotifications.
if buffer.Len() == 0 {
return nil, traceError(errNoSuchNotifications)
}
// Unmarshal notification bytes.
notificationConfigBytes := buffer.Bytes()
notificationCfg := &notificationConfig{}
// Unmarshal notification bytes only if we read data.
if err = xml.Unmarshal(notificationConfigBytes, notificationCfg); err != nil {
return nil, traceError(err)
}
// Return success.
return notificationCfg, nil
}
// loads notification config if any for a given bucket, returns
// structured notification config.
func loadListenerConfig(bucket string, objAPI ObjectLayer) ([]listenerConfig, error) {
// in single node mode, there are no peers, so in this case
// there is no configuration to load, as any previously
// connected listen clients have been disconnected
if !globalIsDistXL {
return nil, nil
}
// Construct the notification config path.
lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
if err := objLock.GetRLock(globalOperationTimeout); err != nil {
return nil, err
}
defer objLock.RUnlock()
var buffer bytes.Buffer
err := objAPI.GetObject(minioMetaBucket, lcPath, 0, -1, &buffer)
if err != nil {
// 'listener.json' not found return
// 'errNoSuchNotifications'. This is default when no
// bucket listeners are found on the bucket
if isErrObjectNotFound(err) || isErrIncompleteBody(err) {
return nil, traceError(errNoSuchNotifications)
}
errorIf(err, "Unable to load bucket-listeners for bucket %s", bucket)
// Returns error for other errors.
return nil, err
}
// if `listener.json` is empty we should return NoSuchNotifications.
if buffer.Len() == 0 {
return nil, traceError(errNoSuchNotifications)
}
var lCfg []listenerConfig
lConfigBytes := buffer.Bytes()
if err = json.Unmarshal(lConfigBytes, &lCfg); err != nil {
errorIf(err, "Unable to unmarshal listener config from JSON.")
return nil, traceError(err)
}
// Return success.
return lCfg, nil
}
func persistNotificationConfig(bucket string, ncfg *notificationConfig, obj ObjectLayer) error {
// marshal to xml
buf, err := xml.Marshal(ncfg)
if err != nil {
errorIf(err, "Unable to marshal notification configuration into XML")
return err
}
// build path
ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
if err = objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
// write object to path
sha256Sum := getSHA256Hash(buf)
_, err = obj.PutObject(minioMetaBucket, ncPath, NewHashReader(bytes.NewReader(buf), int64(len(buf)), "", sha256Sum), nil)
if err != nil {
errorIf(err, "Unable to write bucket notification configuration.")
return err
}
return nil
}
// Persists validated listener config to object layer.
func persistListenerConfig(bucket string, lcfg []listenerConfig, obj ObjectLayer) error {
buf, err := json.Marshal(lcfg)
if err != nil {
errorIf(err, "Unable to marshal listener config to JSON.")
return err
}
// build path
lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
if err = objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
// write object to path
sha256Sum := getSHA256Hash(buf)
_, err = obj.PutObject(minioMetaBucket, lcPath, NewHashReader(bytes.NewReader(buf), int64(len(buf)), "", sha256Sum), nil)
if err != nil {
errorIf(err, "Unable to write bucket listener configuration to object layer.")
}
return err
}
// Removes notification.xml for a given bucket, only used during DeleteBucket.
func removeNotificationConfig(bucket string, objAPI ObjectLayer) error {
// Verify bucket is valid.
if !IsValidBucketName(bucket) {
return BucketNameInvalid{Bucket: bucket}
}
ncPath := path.Join(bucketConfigPrefix, bucket, bucketNotificationConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, ncPath)
if err := objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
return objAPI.DeleteObject(minioMetaBucket, ncPath)
}
// Remove listener configuration from storage layer. Used when a bucket is deleted.
func removeListenerConfig(bucket string, objAPI ObjectLayer) error {
// make the path
lcPath := path.Join(bucketConfigPrefix, bucket, bucketListenerConfig)
// Acquire a write lock on notification config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, lcPath)
if err := objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
return objAPI.DeleteObject(minioMetaBucket, lcPath)
}
// Loads both notification and listener config.
func loadNotificationAndListenerConfig(bucketName string, objAPI ObjectLayer) (nCfg *notificationConfig, lCfg []listenerConfig, err error) {
// Loads notification config if any.
nCfg, err = loadNotificationConfig(bucketName, objAPI)
if err != nil && !isErrIgnored(err, errDiskNotFound, errNoSuchNotifications) {
return nil, nil, err
}
// Loads listener config if any.
lCfg, err = loadListenerConfig(bucketName, objAPI)
if err != nil && !isErrIgnored(err, errDiskNotFound, errNoSuchNotifications) {
return nil, nil, err
}
return nCfg, lCfg, nil
}
// loads all bucket notifications if present.
func loadAllBucketNotifications(objAPI ObjectLayer) (map[string]*notificationConfig, map[string][]listenerConfig, error) {
// List buckets to proceed loading all notification configuration.
buckets, err := objAPI.ListBuckets()
if err != nil {
return nil, nil, err
}
nConfigs := make(map[string]*notificationConfig)
lConfigs := make(map[string][]listenerConfig)
// Loads all bucket notifications.
for _, bucket := range buckets {
// Load persistent notification and listener configurations
// a given bucket name.
nConfigs[bucket.Name], lConfigs[bucket.Name], err = loadNotificationAndListenerConfig(bucket.Name, objAPI)
if err != nil {
return nil, nil, err
}
}
// Success.
return nConfigs, lConfigs, nil
}
// addQueueTarget - calls newTargetFunc function and adds its returned value to queueTargets
func addQueueTarget(queueTargets map[string]*logrus.Logger,
accountID, queueType string,
newTargetFunc func(string) (*logrus.Logger, error)) (string, error) {
// Construct the queue ARN for AMQP.
queueARN := minioSqs + serverConfig.GetRegion() + ":" + accountID + ":" + queueType
// Queue target if already initialized we move to the next ARN.
if _, ok := queueTargets[queueARN]; ok {
return queueARN, nil
}
// Using accountID we can now initialize a new AMQP logrus instance.
logger, err := newTargetFunc(accountID)
if err == nil {
queueTargets[queueARN] = logger
}
return queueARN, err
}
// Loads all queue targets, initializes each queueARNs depending on their config.
// Each instance of queueARN registers its own logrus to communicate with the
// queue service. QueueARN once initialized is not initialized again for the
// same queueARN, instead previous connection is used.
func loadAllQueueTargets() (map[string]*logrus.Logger, error) {
queueTargets := make(map[string]*logrus.Logger)
// Load all amqp targets, initialize their respective loggers.
for accountID, amqpN := range serverConfig.Notify.GetAMQP() {
if !amqpN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeAMQP, newAMQPNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load all mqtt targets, initialize their respective loggers.
for accountID, mqttN := range serverConfig.Notify.GetMQTT() {
if !mqttN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeMQTT, newMQTTNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load all nats targets, initialize their respective loggers.
for accountID, natsN := range serverConfig.Notify.GetNATS() {
if !natsN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeNATS, newNATSNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load redis targets, initialize their respective loggers.
for accountID, redisN := range serverConfig.Notify.GetRedis() {
if !redisN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeRedis, newRedisNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load Webhook targets, initialize their respective loggers.
for accountID, webhookN := range serverConfig.Notify.GetWebhook() {
if !webhookN.Enable {
continue
}
if _, err := addQueueTarget(queueTargets, accountID, queueTypeWebhook, newWebhookNotify); err != nil {
return nil, err
}
}
// Load elastic targets, initialize their respective loggers.
for accountID, elasticN := range serverConfig.Notify.GetElasticSearch() {
if !elasticN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeElastic, newElasticNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load PostgreSQL targets, initialize their respective loggers.
for accountID, pgN := range serverConfig.Notify.GetPostgreSQL() {
if !pgN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypePostgreSQL, newPostgreSQLNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load MySQL targets, initialize their respective loggers.
for accountID, msqlN := range serverConfig.Notify.GetMySQL() {
if !msqlN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeMySQL, newMySQLNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Load Kafka targets, initialize their respective loggers.
for accountID, kafkaN := range serverConfig.Notify.GetKafka() {
if !kafkaN.Enable {
continue
}
if queueARN, err := addQueueTarget(queueTargets, accountID, queueTypeKafka, newKafkaNotify); err != nil {
if _, ok := err.(net.Error); ok {
err = &net.OpError{
Op: "Connecting to " + queueARN,
Net: "tcp",
Err: err,
}
}
return nil, err
}
}
// Successfully initialized queue targets.
return queueTargets, nil
}
// Global instance of event notification queue.
var globalEventNotifier *eventNotifier
// Initialize event notifier.
func initEventNotifier(objAPI ObjectLayer) error {
if objAPI == nil {
return errInvalidArgument
}
// Read all saved bucket notifications.
nConfigs, lConfigs, err := loadAllBucketNotifications(objAPI)
if err != nil {
errorIf(err, "Error loading bucket notifications - %v", err)
return err
}
// Initializes all queue targets.
queueTargets, err := loadAllQueueTargets()
if err != nil {
return err
}
// Initialize internal listener targets
listenTargets := make(map[string]*listenerLogger)
for _, listeners := range lConfigs {
for _, listener := range listeners {
ln, err := newListenerLogger(
listener.TopicConfig.TopicARN,
listener.TargetServer,
)
if err != nil {
errorIf(err, "Unable to initialize listener target logger.")
//TODO: improve error
return fmt.Errorf("Error initializing listner target logger - %v", err)
}
listenTargets[listener.TopicConfig.TopicARN] = ln
}
}
// Initialize event notifier queue.
globalEventNotifier = &eventNotifier{
external: externalNotifier{
notificationConfigs: nConfigs,
targets: queueTargets,
rwMutex: &sync.RWMutex{},
},
internal: internalNotifier{
rwMutex: &sync.RWMutex{},
targets: listenTargets,
listenerConfigs: lConfigs,
connectedListeners: make(map[string]chan []NotificationEvent),
},
}
return nil
}