Add default_field option to fields.yml

The number of fields in the Elasticsearch index template's `settings.index.query.default_field` option has grown over time, and is now greater than 1024 in Filebeat (Elastic licensed version). This causes queries to Elasticsearch to fail when a list of fields is not specified because there is a default limit of 1024 in Elasticsearch.

This adds a new setting to fields.yml called `default_field` whose value can be true/false (defaults to true). When true the text/keyword fields are added to the `default_field` list (as was the behavior before this change). And when set to false the field is omitted from the default_field list.

This adds a test for every beat to check if the default_field list contains more than 1000 fields. The limit is a little less than 1024 because `fields.*` is in the default_field list already and at query time that wildcard will be expanded and count toward the limit.

Fixes elastic#14262

CHANGELOG-developer.next.asciidoc

@@ -58,3 +58,4 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - Makefile included in generator copies files from beats repository using `git archive` instead of cp. {pull}13193[13193]
 - Strip debug symbols from binaries to reduce binary sizes. {issue}12768[12768]
 - Compare event by event in `testadata` framework to avoid sorting problems {pull}13747[13747]
+- Added a `default_field` option to fields in fields.yml to offer a way to exclude fields from the default_field list. {issue}14262[14262] {pull}14341[14341]

auditbeat/main_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/elastic/beats/auditbeat/cmd"
+	"github.com/elastic/beats/libbeat/tests/system/template"
 )
 
 var systemTest *bool
@@ -41,3 +42,7 @@ func TestSystem(t *testing.T) {
 		main()
 	}
 }
+
+func TestTemplate(t *testing.T) {
+	template.TestTemplate(t, cmd.Name)
+}

filebeat/main_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/elastic/beats/filebeat/cmd"
+	"github.com/elastic/beats/libbeat/tests/system/template"
 )
 
 var systemTest *bool
@@ -40,3 +41,7 @@ func TestSystem(t *testing.T) {
 		main()
 	}
 }
+
+func TestTemplate(t *testing.T) {
+	template.TestTemplate(t, cmd.Name)
+}

heartbeat/main_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/elastic/beats/heartbeat/cmd"
+	"github.com/elastic/beats/libbeat/tests/system/template"
 )
 
 var systemTest *bool
@@ -40,3 +41,7 @@ func TestSystem(t *testing.T) {
 		main()
 	}
 }
+
+func TestTemplate(t *testing.T) {
+	template.TestTemplate(t, cmd.Name)
+}

journalbeat/main_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/elastic/beats/journalbeat/cmd"
+	"github.com/elastic/beats/libbeat/tests/system/template"
 )
 
 var systemTest *bool
@@ -37,8 +38,11 @@ func init() {
 
 // Test started when the test binary is started. Only calls main.
 func TestSystem(t *testing.T) {
-
 	if *systemTest {
 		main()
 	}
 }
+
+func TestTemplate(t *testing.T) {
+	template.TestTemplate(t, cmd.Name)
+}

libbeat/libbeat_test.go

@@ -20,6 +20,8 @@ package main
 import (
 	"flag"
 	"testing"
+
+	"github.com/elastic/beats/libbeat/tests/system/template"
 )
 
 var systemTest *bool
@@ -37,3 +39,7 @@ func TestSystem(t *testing.T) {
 		main()
 	}
 }
+
+func TestTemplate(t *testing.T) {
+	template.TestTemplate(t, "mockbeat")
+}

libbeat/mapping/field.go

@@ -76,8 +76,9 @@ type Field struct {
 	UrlTemplate          []VersionizedString `config:"url_template"`
 	OpenLinkInCurrentTab *bool               `config:"open_link_in_current_tab"`
 
-	Overwrite bool `config:"overwrite"`
-	Path      string
+	Overwrite    bool  `config:"overwrite"`
+	DefaultField *bool `config:"default_field"`
+	Path         string
 }
 
 // ObjectTypeCfg defines type and configuration of object attributes

libbeat/template/processor.go

@@ -38,15 +38,27 @@ var (
 
 const scalingFactorKey = "scalingFactor"
 
+type fieldState struct {
+	DefaultField bool
+	Path         string
+}
+
 // Process recursively processes the given fields and writes the template in the given output
-func (p *Processor) Process(fields mapping.Fields, path string, output common.MapStr) error {
-	for _, field := range fields {
+func (p *Processor) Process(fields mapping.Fields, state *fieldState, output common.MapStr) error {
+	if state == nil {
+		// Set the defaults.
+		state = &fieldState{DefaultField: true}
+	}
 
+	for _, field := range fields {
 		if field.Name == "" {
 			continue
 		}
 
-		field.Path = path
+		field.Path = state.Path
+		if field.DefaultField == nil {
+			field.DefaultField = &state.DefaultField
+		}
 		var indexMapping common.MapStr
 
 		switch field.Type {
@@ -69,12 +81,6 @@ func (p *Processor) Process(fields mapping.Fields, path string, output common.Ma
 		case "alias":
 			indexMapping = p.alias(&field)
 		case "group":
-			var newPath string
-			if path == "" {
-				newPath = field.Name
-			} else {
-				newPath = path + "." + field.Name
-			}
 			indexMapping = common.MapStr{}
 			if field.Dynamic.Value != nil {
 				indexMapping["dynamic"] = field.Dynamic.Value
@@ -93,17 +99,26 @@ func (p *Processor) Process(fields mapping.Fields, path string, output common.Ma
 				}
 			}
 
-			if err := p.Process(field.Fields, newPath, properties); err != nil {
+			groupState := &fieldState{Path: field.Name, DefaultField: true}
+			if state.Path != "" {
+				groupState.Path = state.Path + "." + field.Name
+			}
+			if field.DefaultField != nil {
+				groupState.DefaultField = *field.DefaultField
+			}
+			if err := p.Process(field.Fields, groupState, properties); err != nil {
 				return err
 			}
 			indexMapping["properties"] = properties
 		default:
 			indexMapping = p.other(&field)
 		}
 
-		switch field.Type {
-		case "", "keyword", "text":
-			addToDefaultFields(&field)
+		if field.DefaultField == nil || *field.DefaultField {
+			switch field.Type {
+			case "", "keyword", "text":
+				addToDefaultFields(&field)
+			}
 		}
 
 		if len(indexMapping) > 0 {
@@ -207,7 +222,7 @@ func (p *Processor) keyword(f *mapping.Field) common.MapStr {
 
 	if len(f.MultiFields) > 0 {
 		fields := common.MapStr{}
-		p.Process(f.MultiFields, "", fields)
+		p.Process(f.MultiFields, nil, fields)
 		property["fields"] = fields
 	}
 
@@ -243,7 +258,7 @@ func (p *Processor) text(f *mapping.Field) common.MapStr {
 
 	if len(f.MultiFields) > 0 {
 		fields := common.MapStr{}
-		p.Process(f.MultiFields, "", fields)
+		p.Process(f.MultiFields, nil, fields)
 		properties["fields"] = fields
 	}
 

libbeat/template/processor_test.go

@@ -522,7 +522,7 @@ func TestPropertiesCombine(t *testing.T) {
 	}
 
 	p := Processor{EsVersion: *version}
-	err = p.Process(fields, "", output)
+	err = p.Process(fields, nil, output)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -570,7 +570,7 @@ func TestProcessNoName(t *testing.T) {
 	}
 
 	p := Processor{EsVersion: *version}
-	err = p.Process(fields, "", output)
+	err = p.Process(fields, nil, output)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -589,3 +589,81 @@ func TestProcessNoName(t *testing.T) {
 
 	assert.Equal(t, expectedOutput, output)
 }
+
+func TestProcessDefaultField(t *testing.T) {
+	// NOTE: This package stores global state. It must be cleared before this test.
+	defaultFields = nil
+
+	var (
+		enableDefaultField  = true
+		disableDefaultField = false
+	)
+
+	fields := mapping.Fields{
+		// By default foo will be included in default_field.
+		mapping.Field{
+			Name: "foo",
+			Type: "keyword",
+		},
+		// bar is explicitly set to be included in default_field.
+		mapping.Field{
+			Name:         "bar",
+			Type:         "keyword",
+			DefaultField: &enableDefaultField,
+		},
+		// baz is explicitly set to be excluded from default_field.
+		mapping.Field{
+			Name:         "baz",
+			Type:         "keyword",
+			DefaultField: &disableDefaultField,
+		},
+		mapping.Field{
+			Name:         "nested",
+			Type:         "group",
+			DefaultField: &enableDefaultField,
+			Fields: mapping.Fields{
+				mapping.Field{
+					Name: "bar",
+					Type: "keyword",
+				},
+			},
+		},
+		// The nested group is disabled default_field but one of the children
+		// has explicitly requested to be included.
+		mapping.Field{
+			Name:         "nested",
+			Type:         "group",
+			DefaultField: &disableDefaultField,
+			Fields: mapping.Fields{
+				mapping.Field{
+					Name:         "foo",
+					Type:         "keyword",
+					DefaultField: &enableDefaultField,
+				},
+				mapping.Field{
+					Name: "baz",
+					Type: "keyword",
+				},
+			},
+		},
+	}
+
+	version, err := common.NewVersion("7.0.0")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p := Processor{EsVersion: *version}
+	output := common.MapStr{}
+	if err = p.Process(fields, nil, output); err != nil {
+		t.Fatal(err)
+	}
+
+	assert.Len(t, defaultFields, 4)
+	assert.Contains(t, defaultFields,
+		"foo",
+		"bar",
+		"nested.foo",
+		"nested.bar",
+	)
+}

libbeat/template/template.go

@@ -155,7 +155,7 @@ func (t *Template) load(fields mapping.Fields) (common.MapStr, error) {
 	// Start processing at the root
 	properties := common.MapStr{}
 	processor := Processor{EsVersion: t.esVersion, Migration: t.migration}
-	if err := processor.Process(fields, "", properties); err != nil {
+	if err := processor.Process(fields, nil, properties); err != nil {
 		return nil, err
 	}
 	output := t.Generate(properties, dynamicTemplates)

libbeat/tests/system/template/template.go

@@ -0,0 +1,85 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 template
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/elastic/beats/libbeat/asset"
+	"github.com/elastic/beats/libbeat/common"
+	"github.com/elastic/beats/libbeat/template"
+	"github.com/elastic/beats/libbeat/version"
+)
+
+// MaxDefaultFieldLength is the limit on the number of default_field values
+// allowed by the test.
+const MaxDefaultFieldLength = 1000
+
+// TestTemplate executes tests on the Beat's index template.
+func TestTemplate(t *testing.T, beatName string) {
+	t.Run("default_field length", testTemplateDefaultFieldLength(beatName))
+}
+
+// testTemplateDefaultFieldLength constructs a template based on the embedded
+// fields.yml data verifies that the length is less than 1000.
+func testTemplateDefaultFieldLength(beatName string) func(*testing.T) {
+	return func(t *testing.T) {
+		// 7.0 is when default_field was introduced.
+		esVersion, err := common.NewVersion("7.0.0")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		// Generate a template based on the embedded fields.yml data.
+		tmpl, err := template.New(version.GetDefaultVersion(), beatName, *esVersion, template.TemplateConfig{}, false)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		fieldsBytes, err := asset.GetFields(beatName)
+		if err != nil {
+			t.Fatal("Failed to get embedded fields.yml asset data:", err)
+		}
+
+		fields, err := tmpl.LoadBytes(fieldsBytes)
+		if err != nil {
+			t.Fatal("Failed to load template bytes:", err)
+		}
+
+		templateMap := tmpl.Generate(fields, nil)
+
+		v, _ := templateMap.GetValue("settings.index.query.default_field")
+		defaultValue, ok := v.([]string)
+		if !ok {
+			t.Fatalf("settings.index.query.default_field value has an unexpected type: %T", v)
+		}
+
+		if len(defaultValue) > MaxDefaultFieldLength {
+			t.Fatalf("Too many fields (%d>%d) in %v index template"+
+				"settings.index.query.default_field for comfort. By default "+
+				"Elasticsearch has a limit of 1024 fields in a query so we need "+
+				"to keep the number of fields below 1024. Adding 'default_field: "+
+				"false' to fields or groups in a fields.yml can be used to "+
+				"reduce the number of text/keyword fields that end up in "+
+				"default_field.",
+				len(defaultValue), MaxDefaultFieldLength, strings.Title(beatName))
+		}
+		t.Logf("%v template has %d fields in default_field.", strings.Title(beatName), len(defaultValue))
+	}
+}