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/search_queries_template_query.go

@@ -0,0 +1,84 @@
+// Copyright 2012-2015 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
+
+// TemplateQuery is a query that accepts a query template and a
+// map of key/value pairs to fill in template parameters.
+//
+// For more details, see
+// https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-template-query.html
+type TemplateQuery struct {
+	template     string
+	templateType string
+	vars         map[string]interface{}
+}
+
+// NewTemplateQuery creates and initializes a new TemplateQuery.
+func NewTemplateQuery(name string) *TemplateQuery {
+	return &TemplateQuery{
+		template: name,
+		vars:     make(map[string]interface{}),
+	}
+}
+
+// Template specifies the name of the template.
+func (q *TemplateQuery) Template(name string) *TemplateQuery {
+	q.template = name
+	return q
+}
+
+// TemplateType defines which kind of query we use. The values can be:
+// inline, indexed, or file. If undefined, inline is used.
+func (q *TemplateQuery) TemplateType(typ string) *TemplateQuery {
+	q.templateType = typ
+	return q
+}
+
+// Var sets a single parameter pair.
+func (q *TemplateQuery) Var(name string, value interface{}) *TemplateQuery {
+	q.vars[name] = value
+	return q
+}
+
+// Vars sets parameters for the template query.
+func (q *TemplateQuery) Vars(vars map[string]interface{}) *TemplateQuery {
+	q.vars = vars
+	return q
+}
+
+// Source returns the JSON serializable content for the search.
+func (q *TemplateQuery) Source() (interface{}, error) {
+	// {
+	//   "template" : {
+	//     "query" : {"match_{{template}}": {}},
+	//     "params" : {
+	//       "template": "all"
+	//     }
+	//   }
+	// }
+
+	query := make(map[string]interface{})
+
+	tmpl := make(map[string]interface{})
+	query["template"] = tmpl
+
+	// TODO(oe): Implementation differs from online documentation at http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-template-query.html
+	var fieldname string
+	switch q.templateType {
+	case "file": // file
+		fieldname = "file"
+	case "indexed", "id": // indexed
+		fieldname = "id"
+	default: // inline
+		fieldname = "query"
+	}
+
+	tmpl[fieldname] = q.template
+	if len(q.vars) > 0 {
+		tmpl["params"] = q.vars
+	}
+
+	return query, nil
+}