Add support for DelMarkerExpiration element

pkg/lifecycle:
- Add marshal/unmarshal support for DelMarkerExpiration action

pkg/notification:
- Add bucket event type for deletion of all versions of an object with
  DEL marker for current version
  "s3:LifecycleDelMarkerExpiration:Delete"

pkg/lifecycle/lifecycle.go

@@ -414,11 +414,32 @@ func (e Expiration) MarshalXML(en *xml.Encoder, startElement xml.StartElement) e
 	return en.EncodeElement(expirationWrapper(e), startElement)
 }
 
+// DelMarkerExpiration represents DelMarkerExpiration actions element in an ILM policy
+type DelMarkerExpiration struct {
+	XMLName xml.Name `xml:"DelMarkerExpiration" json:"-"`
+	Days    int      `xml:"Days,omitempty" json:"Days,omitempty"`
+}
+
+// IsNull returns true if Days isn't specified and false otherwise.
+func (de DelMarkerExpiration) IsNull() bool {
+	return de.Days == 0
+}
+
+// MarshalXML avoids serializing an empty DelMarkerExpiration element
+func (de DelMarkerExpiration) MarshalXML(enc *xml.Encoder, start xml.StartElement) error {
+	if de.IsNull() {
+		return nil
+	}
+	type delMarkerExp DelMarkerExpiration
+	return enc.EncodeElement(delMarkerExp(de), start)
+}
+
 // MarshalJSON customizes json encoding by omitting empty values
 func (r Rule) MarshalJSON() ([]byte, error) {
 	type rule struct {
 		AbortIncompleteMultipartUpload *AbortIncompleteMultipartUpload `json:"AbortIncompleteMultipartUpload,omitempty"`
 		Expiration                     *Expiration                     `json:"Expiration,omitempty"`
+		DelMarkerExpiration            *DelMarkerExpiration            `json:"DelMarkerExpiration,omitempty"`
 		ID                             string                          `json:"ID"`
 		RuleFilter                     *Filter                         `json:"Filter,omitempty"`
 		NoncurrentVersionExpiration    *NoncurrentVersionExpiration    `json:"NoncurrentVersionExpiration,omitempty"`
@@ -442,6 +463,9 @@ func (r Rule) MarshalJSON() ([]byte, error) {
 	if !r.Expiration.IsNull() {
 		newr.Expiration = &r.Expiration
 	}
+	if !r.DelMarkerExpiration.IsNull() {
+		newr.DelMarkerExpiration = &r.DelMarkerExpiration
+	}
 	if !r.Transition.IsNull() {
 		newr.Transition = &r.Transition
 	}
@@ -460,6 +484,7 @@ type Rule struct {
 	XMLName                        xml.Name                       `xml:"Rule,omitempty" json:"-"`
 	AbortIncompleteMultipartUpload AbortIncompleteMultipartUpload `xml:"AbortIncompleteMultipartUpload,omitempty" json:"AbortIncompleteMultipartUpload,omitempty"`
 	Expiration                     Expiration                     `xml:"Expiration,omitempty" json:"Expiration,omitempty"`
+	DelMarkerExpiration            DelMarkerExpiration            `xml:"DelMarkerExpiration,omitempty" json:"DelMarkerExpiration,omitempty"`
 	ID                             string                         `xml:"ID" json:"ID"`
 	RuleFilter                     Filter                         `xml:"Filter,omitempty" json:"Filter,omitempty"`
 	NoncurrentVersionExpiration    NoncurrentVersionExpiration    `xml:"NoncurrentVersionExpiration,omitempty"  json:"NoncurrentVersionExpiration,omitempty"`

pkg/notification/notification.go

@@ -50,6 +50,7 @@ const (
 	ObjectRemovedAll                                   EventType = "s3:ObjectRemoved:*"
 	ObjectRemovedDelete                                EventType = "s3:ObjectRemoved:Delete"
 	ObjectRemovedDeleteMarkerCreated                   EventType = "s3:ObjectRemoved:DeleteMarkerCreated"
+	ILMDelMarkerExpirationDelete                       EventType = "s3:LifecycleDelMarkerExpiration:Delete"
 	ObjectReducedRedundancyLostObject                  EventType = "s3:ReducedRedundancyLostObject"
 	ObjectTransitionAll                                EventType = "s3:ObjectTransition:*"
 	ObjectTransitionFailed                             EventType = "s3:ObjectTransition:Failed"