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

api-errors.go

@@ -105,6 +105,12 @@ const (
 	ErrBucketAlreadyOwnedByYou
 	// Add new error codes here.
 
+	// Bucket notification related errors.
+	ErrEventNotification
+	ErrARNNotification
+	ErrRegionNotification
+	ErrOverlappingFilterNotification
+
 	// S3 extended errors.
 	ErrContentSHA256Mismatch
 
@@ -411,6 +417,28 @@ var errorCodeResponse = map[APIErrorCode]APIError{
 		HTTPStatusCode: http.StatusConflict,
 	},
 
+	/// Bucket notification related errors.
+	ErrEventNotification: {
+		Code:           "InvalidArgument",
+		Description:    "A specified event is not supported for notifications.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
+	ErrARNNotification: {
+		Code:           "InvalidArgument",
+		Description:    "A specified destination ARN does not exist or is not well-formed. Verify the destination ARN.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
+	ErrRegionNotification: {
+		Code:           "InvalidArgument",
+		Description:    "A specified destination is in a different region than the bucket. You must use a destination that resides in the same region as the bucket.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
+	ErrOverlappingFilterNotification: {
+		Code:           "InvalidArgument",
+		Description:    "An object key name filtering rule defined with overlapping prefixes, overlapping suffixes, or overlapping combinations of prefixes and suffixes for the same event types.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
+
 	/// S3 extensions.
 	ErrContentSHA256Mismatch: {
 		Code:           "XAmzContentSHA256Mismatch",