Merge pull request #125 from devtron-labs/env-gen-common-lib-move

chore: env gen common lib

common-lib/fetchAllEnv/fetchAllEnv.go

@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2024. Devtron Inc.
+ *
+ * Licensed 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 fetchAllEnv
+
+import (
+	"encoding/json"
+	"errors"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"log"
+	"os"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"strings"
+	"text/template"
+)
+
+type EnvField struct {
+	Env            string
+	EnvType        string
+	EnvValue       string
+	EnvDescription string
+	Example        string
+	Deprecated     string
+}
+
+type CategoryField struct {
+	Category string
+	Fields   []EnvField
+}
+
+const (
+	categoryCommentStructPrefix = "CATEGORY="
+	defaultCategory             = "DEVTRON"
+	deprecatedDefaultValue      = "false"
+
+	envFieldTypeTag               = "env"
+	envDefaultFieldTypeTag        = "envDefault"
+	envDescriptionFieldTypeTag    = "description"
+	envPossibleValuesFieldTypeTag = "example"
+	envDeprecatedFieldTypeTag     = "deprecated"
+	MARKDOWN_FILENAME             = "env_gen.md"
+	MARKDOWN_JSON_FILENAME        = "env_gen.json"
+)
+
+const MarkdownTemplate = `
+{{range . }}
+## {{ .Category }} Related Environment Variables
+| Key   | Type     | Default Value     | Description       | Example       | Deprecated       |
+|-------|----------|-------------------|-------------------|-----------------------|------------------|
+{{range .Fields }} | {{ .Env }} | {{ .EnvType }} |{{ .EnvValue }} | {{ .EnvDescription }} | {{ .Example }} | {{ .Deprecated }} |
+{{end}}
+{{end}}`
+
+func FetchEnvAndWriteToFile() {
+	WalkThroughProject()
+	return
+}
+
+func WalkThroughProject() {
+	categoryFieldsMap := make(map[string][]EnvField)
+	uniqueKeys := make(map[string]bool)
+	err := filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() && strings.HasSuffix(path, ".go") {
+			err = processGoFile(path, categoryFieldsMap, uniqueKeys)
+			if err != nil {
+				log.Println("error in processing go file", err)
+				return err
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return
+	}
+	writeToFile(categoryFieldsMap)
+}
+
+func processGoFile(filePath string, categoryFieldsMap map[string][]EnvField, uniqueKeys map[string]bool) error {
+	fset := token.NewFileSet()
+	node, err := parser.ParseFile(fset, filePath, nil, parser.ParseComments)
+	if err != nil {
+		log.Println("error parsing file:", err)
+		return err
+	}
+	ast.Inspect(node, func(n ast.Node) bool {
+		if genDecl, ok := n.(*ast.GenDecl); ok {
+			// checking if type declaration, one of [func, map, struct, array, channel, interface]
+			if genDecl.Tok == token.TYPE {
+				for _, spec := range genDecl.Specs {
+					if typeSpec, ok := spec.(*ast.TypeSpec); ok {
+						// only checking struct type declarations
+						if structType, ok2 := typeSpec.Type.(*ast.StructType); ok2 {
+							allFields := make([]EnvField, 0, len(structType.Fields.List))
+							for _, field := range structType.Fields.List {
+								if field.Tag != nil {
+									envField := getEnvKeyAndValue(field)
+									envKey := envField.Env
+									if len(envKey) == 0 || uniqueKeys[envKey] {
+										continue
+									}
+									allFields = append(allFields, envField)
+									uniqueKeys[envKey] = true
+								}
+							}
+							if len(allFields) > 0 {
+								category := getCategoryForAStruct(genDecl)
+								categoryFieldsMap[category] = append(categoryFieldsMap[category], allFields...)
+							}
+						}
+					}
+				}
+			}
+		}
+		return true
+	})
+	return nil
+}
+
+func getEnvKeyAndValue(field *ast.Field) EnvField {
+	tag := reflect.StructTag(strings.Trim(field.Tag.Value, "`")) // remove surrounding backticks
+
+	envKey := addReadmeTableDelimiterEscapeChar(tag.Get(envFieldTypeTag))
+	envValue := addReadmeTableDelimiterEscapeChar(tag.Get(envDefaultFieldTypeTag))
+	envDescription := addReadmeTableDelimiterEscapeChar(tag.Get(envDescriptionFieldTypeTag))
+	envPossibleValues := addReadmeTableDelimiterEscapeChar(tag.Get(envPossibleValuesFieldTypeTag))
+	envDeprecated := addReadmeTableDelimiterEscapeChar(tag.Get(envDeprecatedFieldTypeTag))
+	// check if there exist any value provided in env for this field
+	if value, ok := os.LookupEnv(envKey); ok {
+		envValue = value
+	}
+	env := EnvField{
+		Env:            envKey,
+		EnvValue:       envValue,
+		EnvDescription: envDescription,
+		Example:        envPossibleValues,
+		Deprecated:     envDeprecated,
+	}
+	if indent, ok := field.Type.(*ast.Ident); ok && indent != nil {
+		env.EnvType = indent.Name
+	}
+	if len(envDeprecated) == 0 {
+		env.Deprecated = deprecatedDefaultValue
+	}
+	return env
+}
+
+func getCategoryForAStruct(genDecl *ast.GenDecl) string {
+	category := defaultCategory
+	if genDecl.Doc != nil {
+		commentTexts := strings.Split(genDecl.Doc.Text(), "\n")
+		for _, comment := range commentTexts {
+			commentText := strings.TrimPrefix(strings.ReplaceAll(comment, " ", ""), "//") // this can happen if comment group is in /* */
+			if strings.HasPrefix(commentText, categoryCommentStructPrefix) {
+				categories := strings.Split(strings.TrimPrefix(commentText, categoryCommentStructPrefix), ",")
+				if len(categories) > 0 && len(categories[0]) > 0 { //only supporting one category as of now
+					category = categories[0] //overriding category
+					break
+				}
+			}
+		}
+	}
+	return category
+}
+
+func addReadmeTableDelimiterEscapeChar(s string) string {
+	return strings.ReplaceAll(s, "|", `\|`)
+}
+
+func writeToFile(categoryFieldsMap map[string][]EnvField) {
+	cfs := make([]CategoryField, 0, len(categoryFieldsMap))
+	for category, allFields := range categoryFieldsMap {
+		sort.Slice(allFields, func(i, j int) bool {
+			return allFields[i].Env < allFields[j].Env
+		})
+
+		cfs = append(cfs, CategoryField{
+			Category: category,
+			Fields:   allFields,
+		})
+	}
+	sort.Slice(cfs, func(i, j int) bool {
+		return cfs[i].Category < cfs[j].Category
+	})
+	file, err := os.Create(MARKDOWN_FILENAME)
+	if err != nil && !errors.Is(err, os.ErrExist) {
+		panic(err)
+	}
+	defer file.Close()
+	tmpl, err := template.New("markdown").Parse(MarkdownTemplate)
+	if err != nil {
+		panic(err)
+	}
+	err = tmpl.Execute(file, cfs)
+	if err != nil {
+		panic(err)
+	}
+	cfsMarshaled, err := json.Marshal(cfs)
+	if err != nil {
+		log.Println("error marshalling category fields:", err)
+		panic(err)
+	}
+	err = os.WriteFile(MARKDOWN_JSON_FILENAME, cfsMarshaled, 0644)
+	if err != nil {
+		panic(err)
+	}
+}