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

vendor/gopkg.in/olivere/elastic.v3/canonicalize.go

@@ -0,0 +1,38 @@
+// Copyright 2012-present Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+import "net/url"
+
+// canonicalize takes a list of URLs and returns its canonicalized form, i.e.
+// remove anything but scheme, userinfo, host, path, and port.
+// It also removes all trailing slashes. It also skips invalid URLs or
+// URLs that do not use protocol http or https.
+//
+// Example:
+// http://127.0.0.1:9200/?query=1 -> http://127.0.0.1:9200
+// http://127.0.0.1:9200/db1/ -> http://127.0.0.1:9200/db1
+// 127.0.0.1:9200 -> http://127.0.0.1:9200
+func canonicalize(rawurls ...string) []string {
+	var canonicalized []string
+	for _, rawurl := range rawurls {
+		u, err := url.Parse(rawurl)
+		if err == nil {
+			if len(u.Scheme) == 0 {
+				u.Scheme = DefaultScheme
+			}
+			if u.Scheme == "http" || u.Scheme == "https" {
+				// Trim trailing slashes
+				for len(u.Path) > 0 && u.Path[len(u.Path)-1] == '/' {
+					u.Path = u.Path[0 : len(u.Path)-1]
+				}
+				u.Fragment = ""
+				u.RawQuery = ""
+				canonicalized = append(canonicalized, u.String())
+			}
+		}
+	}
+	return canonicalized
+}