Cherry-pick #16570 to 7.x: Add support for histogram type in fields.yml

CHANGELOG.next.asciidoc

@@ -190,6 +190,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add `aws_ec2` provider for autodiscover. {issue}12518[12518] {pull}14823[14823]
 - Add monitoring variable `libbeat.config.scans` to distinguish scans of the configuration directory from actual reloads of its contents. {pull}16440[16440]
 - Add support for multiple password in redis output. {issue}16058[16058] {pull}16206[16206]
+- Add support for Histogram type in fields.yml {pull}16570[16570]
 - Remove experimental flag from `setup.template.append_fields` {pull}16576[16576]
 - Add `add_cloudfoundry_metadata` processor to annotate events with Cloud Foundry application data. {pull}16621[16621]
 

libbeat/mapping/field.go

@@ -134,7 +134,7 @@ func (f *Field) validateType() error {
 		return geoPointType.validate(f.Format)
 	case "date_range":
 		return dateRangeType.validate(f.Format)
-	case "boolean", "binary", "ip", "alias", "array":
+	case "boolean", "binary", "ip", "alias", "array", "histogram":
 		if f.Format != "" {
 			return fmt.Errorf("no format expected for field %s, found: %s", f.Name, f.Format)
 		}

libbeat/template/processor.go

@@ -80,6 +80,8 @@ func (p *Processor) Process(fields mapping.Fields, state *fieldState, output com
 			indexMapping = p.array(&field)
 		case "alias":
 			indexMapping = p.alias(&field)
+		case "histogram":
+			indexMapping = p.histogram(&field)
 		case "group":
 			indexMapping = common.MapStr{}
 			if field.Dynamic.Value != nil {
@@ -287,6 +289,18 @@ func (p *Processor) alias(f *mapping.Field) common.MapStr {
 	return properties
 }
 
+func (p *Processor) histogram(f *mapping.Field) common.MapStr {
+	// Histograms were introduced in Elasticsearch 7.6, ignore if unsupported
+	if p.EsVersion.LessThan(common.MustNewVersion("7.6.0")) {
+		return nil
+	}
+
+	properties := getDefaultProperties(f)
+	properties["type"] = "histogram"
+
+	return properties
+}
+
 func (p *Processor) object(f *mapping.Field) common.MapStr {
 	matchType := func(onlyType string, mt string) string {
 		if mt != "" {
@@ -324,6 +338,9 @@ func (p *Processor) object(f *mapping.Field) common.MapStr {
 		case "byte", "double", "float", "long", "short", "boolean":
 			dynProperties["type"] = otp.ObjectType
 			addDynamicTemplate(f, dynProperties, matchType(otp.ObjectType, otp.ObjectTypeMappingType))
+		case "histogram":
+			dynProperties["type"] = otp.ObjectType
+			addDynamicTemplate(f, dynProperties, matchType("*", otp.ObjectTypeMappingType))
 		}
 	}
 

libbeat/template/processor_test.go

@@ -34,6 +34,7 @@ func TestProcessor(t *testing.T) {
 	pEsVersion2 := &Processor{EsVersion: *common.MustNewVersion("2.0.0")}
 	pEsVersion64 := &Processor{EsVersion: *common.MustNewVersion("6.4.0")}
 	pEsVersion63 := &Processor{EsVersion: *common.MustNewVersion("6.3.6")}
+	pEsVersion76 := &Processor{EsVersion: *common.MustNewVersion("7.6.0")}
 
 	tests := []struct {
 		output   common.MapStr
@@ -300,6 +301,14 @@ func TestProcessor(t *testing.T) {
 			output:   migrationP.alias(&mapping.Field{Type: "alias", AliasPath: "a.f", MigrationAlias: true}),
 			expected: common.MapStr{"path": "a.f", "type": "alias"},
 		},
+		{
+			output:   p.histogram(&mapping.Field{Type: "histogram"}),
+			expected: nil,
+		},
+		{
+			output:   pEsVersion76.histogram(&mapping.Field{Type: "histogram"}),
+			expected: common.MapStr{"type": "histogram"},
+		},
 	}
 
 	for _, test := range tests {