api: Implement bucket notification. (#2271)

* Implement basic S3 notifications through queues

Supports multiple queues and three basic queue types:

1. NilQueue -- messages don't get sent anywhere
2. LogQueue -- messages get logged
3. AmqpQueue -- messages are sent to an AMQP queue

* api: Implement bucket notification.

Supports two different queue types

- AMQP
- ElasticSearch.

* Add support for redis

bucket-notification-datatypes.go

@@ -0,0 +1,155 @@
+/*
+ * Minio Cloud Storage, (C) 2016 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 main
+
+import "encoding/xml"
+
+type filterRule struct {
+	Name  string `xml:"FilterRuleName"`
+	Value string
+}
+
+type keyFilter struct {
+	FilterRules []filterRule `xml:"FilterRule"`
+}
+
+type notificationConfigFilter struct {
+	Key keyFilter `xml:"S3Key"`
+}
+
+// Queue SQS configuration.
+type queueConfig struct {
+	Events   []string `xml:"Event"`
+	Filter   notificationConfigFilter
+	ID       string `xml:"Id"`
+	QueueArn string `xml:"Queue"`
+}
+
+// Topic SNS configuration, this is a compliance field
+// not used by minio yet.
+type topicConfig struct {
+	Events   []string `xml:"Event"`
+	Filter   notificationConfigFilter
+	ID       string `xml:"Id"`
+	TopicArn string `xml:"Topic"`
+}
+
+// Lambda function configuration, this is a compliance field
+// not used by minio yet.
+type lambdaFuncConfig struct {
+	Events            []string `xml:"Event"`
+	Filter            notificationConfigFilter
+	ID                string `xml:"Id"`
+	LambdaFunctionArn string `xml:"CloudFunction"`
+}
+
+// Notification configuration structure represents the XML format of
+// notification configuration of buckets.
+type notificationConfig struct {
+	XMLName              xml.Name           `xml:"NotificationConfiguration"`
+	QueueConfigurations  []queueConfig      `xml:"QueueConfiguration"`
+	TopicConfigurations  []topicConfig      `xml:"TopicConfiguration"`
+	LambdaConfigurations []lambdaFuncConfig `xml:"CloudFunctionConfiguration"`
+}
+
+// EventName is AWS S3 event type:
+// http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html
+type EventName int
+
+const (
+	// ObjectCreatedPut is s3:ObjectCreated:Put
+	ObjectCreatedPut EventName = iota
+	// ObjectCreatedPost is s3:ObjectCreated:POst
+	ObjectCreatedPost
+	// ObjectCreatedCopy is s3:ObjectCreated:Post
+	ObjectCreatedCopy
+	// ObjectCreatedCompleteMultipartUpload is s3:ObjectCreated:CompleteMultipartUpload
+	ObjectCreatedCompleteMultipartUpload
+	// ObjectRemovedDelete is s3:ObjectRemoved:Delete
+	ObjectRemovedDelete
+)
+
+// Stringer interface for event name.
+func (eventName EventName) String() string {
+	switch eventName {
+	case ObjectCreatedPut:
+		return "s3:ObjectCreated:Put"
+	case ObjectCreatedPost:
+		return "s3:ObjectCreated:Post"
+	case ObjectCreatedCopy:
+		return "s3:ObjectCreated:Copy"
+	case ObjectCreatedCompleteMultipartUpload:
+		return "s3:ObjectCreated:CompleteMultipartUpload"
+	case ObjectRemovedDelete:
+		return "s3:ObjectRemoved:Delete"
+	default:
+		return "s3:Unknown"
+	}
+}
+
+// Indentity represents the user id, this is a compliance field.
+type identity struct {
+	PrincipalID string `json:"principalId"`
+}
+
+func defaultIdentity() identity {
+	return identity{"minio"}
+}
+
+type s3BucketReference struct {
+	Name          string   `json:"name"`
+	OwnerIdentity identity `json:"ownerIdentity"`
+	ARN           string   `json:"arn"`
+}
+
+type s3ObjectReference struct {
+	Key       string `json:"key"`
+	Size      int64  `json:"size,omitempty"`
+	ETag      string `json:"eTag,omitempty"`
+	VersionID string `json:"versionId,omitempty"`
+	Sequencer string `json:"sequencer"`
+}
+
+type s3Reference struct {
+	SchemaVersion   string            `json:"s3SchemaVersion"`
+	ConfigurationID string            `json:"configurationId"`
+	Bucket          s3BucketReference `json:"bucket"`
+	Object          s3ObjectReference `json:"object"`
+}
+
+// NotificationEvent represents an Amazon an S3 bucket notification event.
+type NotificationEvent struct {
+	EventVersion      string            `json:"eventVersion"`
+	EventSource       string            `json:"eventSource"`
+	AwsRegion         string            `json:"awsRegion"`
+	EventTime         string            `json:"eventTime"`
+	EventName         string            `json:"eventName"`
+	UserIdentity      identity          `json:"userIdentity"`
+	RequestParameters map[string]string `json:"requestParameters"`
+	ResponseElements  map[string]string `json:"responseElements"`
+	S3                s3Reference       `json:"s3"`
+}
+
+// Represents the minio sqs type and inputs.
+type arnMinioSqs struct {
+	sqsType string
+}
+
+// Stringer for constructing AWS ARN compatible string.
+func (m arnMinioSqs) String() string {
+	return minioSqs + serverConfig.GetRegion() + ":" + m.sqsType
+}