Move generator packages of Filebeat from scripts/generator to generat…

…or (elastic#9147)

From now on generator functions are located under generator package.

CHANGELOG-developer.asciidoc

@@ -32,6 +32,7 @@ The list below covers the major changes between 6.3.0 and master only.
 - Outputs must implement String. {pull}6404[6404]
 - Renamed `-beat-name` CLI option used in `kibana_index_pattern.go` to `-beat` for consistency with other scripts in `dev-tools/cmd`. {pull}8615[8615]
 - Removed dashboards and index patterns generation for Kibana 5. {pull}8927[8927]
+- Move generator packages of Filebeat from `scripts/generator` to `generator`. {pull}9147[9147]
 
 ==== Bugfixes
 

filebeat/generator/fields/fields.go

@@ -0,0 +1,389 @@
+// 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 fields
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"reflect"
+	"regexp"
+	"strings"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+const (
+	pipelinePath  = "%s/module/%s/%s/ingest/pipeline.json"
+	fieldsYmlPath = "%s/module/%s/%s/_meta/fields.yml"
+
+	typeIdx     = 0
+	elementsIdx = 1
+	hintIdx     = 2
+)
+
+var (
+	types = map[string]string{
+		"group":           "group",
+		"DATA":            "text",
+		"GREEDYDATA":      "text",
+		"GREEDYMULTILINE": "text",
+		"HOSTNAME":        "keyword",
+		"IPHOST":          "keyword",
+		"IPORHOST":        "keyword",
+		"LOGLEVEL":        "keyword",
+		"MULTILINEQUERY":  "text",
+		"NUMBER":          "long",
+		"POSINT":          "long",
+		"SYSLOGHOST":      "keyword",
+		"SYSLOGTIMESTAMP": "text",
+		"LOCALDATETIME":   "text",
+		"TIMESTAMP":       "text",
+		"USERNAME":        "keyword",
+		"WORD":            "keyword",
+	}
+)
+
+type pipeline struct {
+	Description string                   `json:"description"`
+	Processors  []map[string]interface{} `json:"processors"`
+	OnFailure   interface{}              `json:"on_failure"`
+}
+
+type field struct {
+	Syntax           string
+	SemanticElements []string
+	Type             string
+}
+
+type fieldYml struct {
+	Name        string      `yaml:"name"`
+	Description string      `yaml:"description,omitempty"`
+	Example     string      `yaml:"example,omitempty"`
+	Type        string      `yaml:"type,omitempty"`
+	Fields      []*fieldYml `yaml:"fields,omitempty"`
+}
+
+// Generate reads a pipeline and creates a fields.yml file based on it.
+func Generate(beatsPath, module, fileset string, noDoc bool) error {
+	filesetPath := filepath.Join(beatsPath, "module", module, fileset)
+	p, err := readPipeline(filesetPath)
+	if err != nil {
+		return fmt.Errorf("cannot read pipeline: %+v", err)
+	}
+
+	data, err := p.toFieldsYml(noDoc)
+	if err != nil {
+		return fmt.Errorf("cannot generate fields.yml: %+v", err)
+	}
+
+	err = writeFieldsYml(filesetPath, data)
+	if err != nil {
+		return fmt.Errorf("cannot write field.yml: %+v", err)
+	}
+	return nil
+}
+
+func readPipeline(filesetPath string) (*pipeline, error) {
+	pipelinePath := filepath.Join(filesetPath, "ingest/pipeline.json")
+	r, err := ioutil.ReadFile(pipelinePath)
+	if err != nil {
+		return nil, err
+	}
+
+	var p pipeline
+	err = json.Unmarshal(r, &p)
+	if err != nil {
+		return nil, err
+	}
+
+	return &p, nil
+}
+
+func writeFieldsYml(filesetPath string, fieldsBytes []byte) error {
+	output := filepath.Join(filesetPath, "_meta/fields.yml")
+	return ioutil.WriteFile(output, fieldsBytes, 0644)
+}
+
+func newFieldYml(name, typeName string, noDoc bool) *fieldYml {
+	if noDoc {
+		return &fieldYml{
+			Name: name,
+			Type: typeName,
+		}
+	}
+
+	return &fieldYml{
+		Name:        name,
+		Type:        typeName,
+		Description: "Please add description",
+		Example:     "Please add example",
+	}
+}
+
+func newField(pattern string) field {
+	if len(pattern) <= 2 {
+		return field{}
+	}
+	pattern = pattern[1 : len(pattern)-1]
+
+	elements := strings.Split(pattern, ":")
+	if !isValidFormat(elements) {
+		return field{}
+	}
+
+	hint := ""
+	if containsType(elements) {
+		hint = elements[hintIdx]
+	}
+
+	return field{
+		Syntax:           elements[typeIdx],
+		SemanticElements: strings.Split(elements[elementsIdx], "."),
+		Type:             hint,
+	}
+}
+
+// isValidFormat checks if the input can be split correctly
+// 1. if length is 2, the format is {type}:{field.elements}
+// 2. if the length is 3, the format is {type}:{field.elements}:{hint}
+func isValidFormat(ee []string) bool {
+	return len(ee) == 2 || len(ee) == 3
+}
+
+// the last element is the type hint
+func containsType(ee []string) bool {
+	return len(ee) == 3
+}
+
+func addNewField(fs []field, f field) []field {
+	for _, ff := range fs {
+		if reflect.DeepEqual(ff, f) {
+			return fs
+		}
+	}
+	return append(fs, f)
+}
+
+func getSemanticElementsFromPatterns(patterns []string) ([]field, error) {
+	r, err := regexp.Compile("{[\\.\\w\\:]*}")
+	if err != nil {
+		return nil, err
+	}
+
+	var fs []field
+	for _, lp := range patterns {
+		pp := r.FindAllString(lp, -1)
+		for _, p := range pp {
+			f := newField(p)
+			if f.SemanticElements == nil {
+				continue
+			}
+			fs = addNewField(fs, f)
+		}
+
+	}
+	return fs, nil
+}
+
+func accumulatePatterns(grok interface{}) ([]string, error) {
+	for k, v := range grok.(map[string]interface{}) {
+		if k == "patterns" {
+			vs := v.([]interface{})
+			var p []string
+			for _, s := range vs {
+				p = append(p, s.(string))
+			}
+			return p, nil
+		}
+	}
+	return nil, fmt.Errorf("No patterns in pipeline")
+}
+
+func accumulateRemoveFields(remove interface{}, out []string) []string {
+	for k, v := range remove.(map[string]interface{}) {
+		if k == "field" {
+			switch vs := v.(type) {
+			case string:
+				return append(out, vs)
+			case []string:
+				for _, vv := range vs {
+					out = append(out, vv)
+				}
+			case []interface{}:
+				for _, vv := range vs {
+					vvs := vv.(string)
+					out = append(out, vvs)
+				}
+			default:
+				return out
+
+			}
+		}
+	}
+	return out
+}
+
+func accumulateRenameFields(rename interface{}, out map[string]string) map[string]string {
+	var from, to string
+	for k, v := range rename.(map[string]interface{}) {
+		if k == "field" {
+			from = v.(string)
+		}
+		if k == "target_field" {
+			to = v.(string)
+		}
+	}
+	out[from] = to
+	return out
+}
+
+type processors struct {
+	patterns []string
+	remove   []string
+	rename   map[string]string
+}
+
+func (p *processors) processFields() ([]field, error) {
+	f, err := getSemanticElementsFromPatterns(p.patterns)
+	if err != nil {
+		return nil, err
+	}
+
+	for i, ff := range f {
+		fs := strings.Join(ff.SemanticElements, ".")
+		for k, mv := range p.rename {
+			if k == fs {
+				ff.SemanticElements = strings.Split(mv, ".")
+			}
+		}
+		for _, rm := range p.remove {
+			if fs == rm {
+				f = append(f[:i], f[i+1:]...)
+			}
+		}
+	}
+	return f, nil
+}
+
+func getProcessors(p []map[string]interface{}) (*processors, error) {
+	var patterns, rmFields []string
+	mvFields := make(map[string]string)
+
+	for _, e := range p {
+		if ee, ok := e["grok"]; ok {
+			pp, err := accumulatePatterns(ee)
+			if err != nil {
+				return nil, err
+			}
+			patterns = append(patterns, pp...)
+		}
+		if rm, ok := e["remove"]; ok {
+			rmFields = accumulateRemoveFields(rm, rmFields)
+		}
+		if mv, ok := e["rename"]; ok {
+			mvFields = accumulateRenameFields(mv, mvFields)
+		}
+	}
+
+	if patterns == nil {
+		return nil, fmt.Errorf("No patterns in pipeline")
+	}
+
+	return &processors{
+		patterns: patterns,
+		remove:   rmFields,
+		rename:   mvFields,
+	}, nil
+}
+
+func getFieldByName(f []*fieldYml, name string) *fieldYml {
+	for _, ff := range f {
+		if ff.Name == name {
+			return ff
+		}
+	}
+	return nil
+}
+
+func insertLastField(f []*fieldYml, name string, field field, noDoc bool) []*fieldYml {
+	ff := getFieldByName(f, name)
+	if ff != nil {
+		return f
+	}
+
+	fieldType := field.Type
+	if fieldType == "" {
+		fieldType = types[field.Syntax]
+	}
+	nf := newFieldYml(name, fieldType, noDoc)
+	return append(f, nf)
+}
+
+func insertGroup(out []*fieldYml, field field, index, count int, noDoc bool) []*fieldYml {
+	g := getFieldByName(out, field.SemanticElements[index])
+	if g != nil {
+		g.Fields = generateField(g.Fields, field, index+1, count, noDoc)
+		return out
+	}
+
+	var groupFields []*fieldYml
+	groupFields = generateField(groupFields, field, index+1, count, noDoc)
+	group := newFieldYml(field.SemanticElements[index], "group", noDoc)
+	group.Fields = groupFields
+	return append(out, group)
+}
+
+func generateField(out []*fieldYml, field field, index, count int, noDoc bool) []*fieldYml {
+	if index+1 == count {
+		return insertLastField(out, field.SemanticElements[index], field, noDoc)
+	}
+	return insertGroup(out, field, index, count, noDoc)
+}
+
+func generateFields(f []field, noDoc bool) []*fieldYml {
+	var out []*fieldYml
+	for _, ff := range f {
+		index := 1
+		if len(ff.SemanticElements) == 1 {
+			index = 0
+		}
+		out = generateField(out, ff, index, len(ff.SemanticElements), noDoc)
+	}
+	return out
+}
+
+func (p *pipeline) toFieldsYml(noDoc bool) ([]byte, error) {
+	pr, err := getProcessors(p.Processors)
+	if err != nil {
+		return nil, err
+	}
+
+	var fs []field
+	fs, err = pr.processFields()
+	if err != nil {
+		return nil, err
+	}
+
+	f := generateFields(fs, noDoc)
+	var d []byte
+	d, err = yaml.Marshal(&f)
+
+	return d, nil
+}