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_aggs_pipeline_derivative.go

@@ -0,0 +1,124 @@
+// 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
+
+// DerivativeAggregation is a parent pipeline aggregation which calculates
+// the derivative of a specified metric in a parent histogram (or date_histogram)
+// aggregation. The specified metric must be numeric and the enclosing
+// histogram must have min_doc_count set to 0 (default for histogram aggregations).
+//
+// For more details, see
+// https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-pipeline-derivative-aggregation.html
+type DerivativeAggregation struct {
+	format    string
+	gapPolicy string
+	unit      string
+
+	subAggregations map[string]Aggregation
+	meta            map[string]interface{}
+	bucketsPaths    []string
+}
+
+// NewDerivativeAggregation creates and initializes a new DerivativeAggregation.
+func NewDerivativeAggregation() *DerivativeAggregation {
+	return &DerivativeAggregation{
+		subAggregations: make(map[string]Aggregation),
+		bucketsPaths:    make([]string, 0),
+	}
+}
+
+func (a *DerivativeAggregation) Format(format string) *DerivativeAggregation {
+	a.format = format
+	return a
+}
+
+// GapPolicy defines what should be done when a gap in the series is discovered.
+// Valid values include "insert_zeros" or "skip". Default is "insert_zeros".
+func (a *DerivativeAggregation) GapPolicy(gapPolicy string) *DerivativeAggregation {
+	a.gapPolicy = gapPolicy
+	return a
+}
+
+// GapInsertZeros inserts zeros for gaps in the series.
+func (a *DerivativeAggregation) GapInsertZeros() *DerivativeAggregation {
+	a.gapPolicy = "insert_zeros"
+	return a
+}
+
+// GapSkip skips gaps in the series.
+func (a *DerivativeAggregation) GapSkip() *DerivativeAggregation {
+	a.gapPolicy = "skip"
+	return a
+}
+
+// Unit sets the unit provided, e.g. "1d" or "1y".
+// It is only useful when calculating the derivative using a date_histogram.
+func (a *DerivativeAggregation) Unit(unit string) *DerivativeAggregation {
+	a.unit = unit
+	return a
+}
+
+// SubAggregation adds a sub-aggregation to this aggregation.
+func (a *DerivativeAggregation) SubAggregation(name string, subAggregation Aggregation) *DerivativeAggregation {
+	a.subAggregations[name] = subAggregation
+	return a
+}
+
+// Meta sets the meta data to be included in the aggregation response.
+func (a *DerivativeAggregation) Meta(metaData map[string]interface{}) *DerivativeAggregation {
+	a.meta = metaData
+	return a
+}
+
+// BucketsPath sets the paths to the buckets to use for this pipeline aggregator.
+func (a *DerivativeAggregation) BucketsPath(bucketsPaths ...string) *DerivativeAggregation {
+	a.bucketsPaths = append(a.bucketsPaths, bucketsPaths...)
+	return a
+}
+
+func (a *DerivativeAggregation) Source() (interface{}, error) {
+	source := make(map[string]interface{})
+	params := make(map[string]interface{})
+	source["derivative"] = params
+
+	if a.format != "" {
+		params["format"] = a.format
+	}
+	if a.gapPolicy != "" {
+		params["gap_policy"] = a.gapPolicy
+	}
+	if a.unit != "" {
+		params["unit"] = a.unit
+	}
+
+	// Add buckets paths
+	switch len(a.bucketsPaths) {
+	case 0:
+	case 1:
+		params["buckets_path"] = a.bucketsPaths[0]
+	default:
+		params["buckets_path"] = a.bucketsPaths
+	}
+
+	// AggregationBuilder (SubAggregations)
+	if len(a.subAggregations) > 0 {
+		aggsMap := make(map[string]interface{})
+		source["aggregations"] = aggsMap
+		for name, aggregate := range a.subAggregations {
+			src, err := aggregate.Source()
+			if err != nil {
+				return nil, err
+			}
+			aggsMap[name] = src
+		}
+	}
+
+	// Add Meta data if available
+	if len(a.meta) > 0 {
+		source["meta"] = a.meta
+	}
+
+	return source, nil
+}