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-utils.go

@@ -0,0 +1,128 @@
+/*
+ * 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 "strings"
+
+// List of valid event types.
+var suppportedEventTypes = map[string]struct{}{
+	// Object created event types.
+	"s3:ObjectCreated:*":                       {},
+	"s3:ObjectCreated:Put":                     {},
+	"s3:ObjectCreated:Post":                    {},
+	"s3:ObjectCreated:Copy":                    {},
+	"s3:ObjectCreated:CompleteMultipartUpload": {},
+	// Object removed event types.
+	"s3:ObjectRemoved:*":      {},
+	"s3:ObjectRemoved:Delete": {},
+}
+
+// checkEvent - checks if an event is supported.
+func checkEvent(event string) APIErrorCode {
+	_, ok := suppportedEventTypes[event]
+	if !ok {
+		return ErrEventNotification
+	}
+	return ErrNone
+}
+
+// checkEvents - checks given list of events if all of them are valid.
+// given if one of them is invalid, this function returns an error.
+func checkEvents(events []string) APIErrorCode {
+	for _, event := range events {
+		if s3Error := checkEvent(event); s3Error != ErrNone {
+			return s3Error
+		}
+	}
+	return ErrNone
+}
+
+// checkQueueArn - check if the queue arn is valid.
+func checkQueueArn(queueArn string) APIErrorCode {
+	if !strings.HasPrefix(queueArn, minioSqs) {
+		return ErrARNNotification
+	}
+	if !strings.HasPrefix(queueArn, minioSqs+serverConfig.GetRegion()+":") {
+		return ErrRegionNotification
+	}
+	return ErrNone
+}
+
+// Check - validates queue configuration and returns error if any.
+func checkQueueConfig(qConfig queueConfig) APIErrorCode {
+	// Check queue arn is valid.
+	if s3Error := checkQueueArn(qConfig.QueueArn); s3Error != ErrNone {
+		return s3Error
+	}
+
+	// Unmarshals QueueArn into structured object.
+	sqsArn := unmarshalSqsArn(qConfig.QueueArn)
+	// Validate if sqsArn requested any of the known supported queues.
+	if !isAMQPQueue(sqsArn) || !isElasticQueue(sqsArn) || !isRedisQueue(sqsArn) {
+		return ErrARNNotification
+	}
+
+	// Check if valid events are set in queue config.
+	if s3Error := checkEvents(qConfig.Events); s3Error != ErrNone {
+		return s3Error
+	}
+
+	// Success.
+	return ErrNone
+}
+
+// Validates all incoming queue configs, checkQueueConfig validates if the
+// input fields for each queues is not malformed and has valid configuration
+// information.  If validation fails bucket notifications are not enabled.
+func validateQueueConfigs(queueConfigs []queueConfig) APIErrorCode {
+	for _, qConfig := range queueConfigs {
+		if s3Error := checkQueueConfig(qConfig); s3Error != ErrNone {
+			return s3Error
+		}
+	}
+	// Success.
+	return ErrNone
+}
+
+// Validates all the bucket notification configuration for their validity,
+// if one of the config is malformed or has invalid data it is rejected.
+// Configuration is never applied partially.
+func validateNotificationConfig(nConfig notificationConfig) APIErrorCode {
+	if s3Error := validateQueueConfigs(nConfig.QueueConfigurations); s3Error != ErrNone {
+		return s3Error
+	}
+	// Add validation for other configurations.
+	return ErrNone
+}
+
+// Unmarshals input value of AWS ARN format into minioSqs object.
+// Returned value represents minio sqs types, currently supported are
+// - amqp
+// - elasticsearch
+func unmarshalSqsArn(queueArn string) (mSqs arnMinioSqs) {
+	sqsType := strings.TrimPrefix(queueArn, minioSqs+serverConfig.GetRegion()+":")
+	mSqs = arnMinioSqs{}
+	switch sqsType {
+	case queueTypeAMQP:
+		mSqs.sqsType = queueTypeAMQP
+	case queueTypeElastic:
+		mSqs.sqsType = queueTypeElastic
+	case queueTypeRedis:
+		mSqs.sqsType = queueTypeRedis
+	} // Add more cases here.
+	return mSqs
+}