refactor: openpitrix module
Signed-off-by: hongming <talonwan@yunify.com>
This commit is contained in:
hongming
263
vendor/openpitrix.io/openpitrix/pkg/config/env_loader.go
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vendored
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263
vendor/openpitrix.io/openpitrix/pkg/config/env_loader.go
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package config
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import (
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"flag"
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"fmt"
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"os"
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"reflect"
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"strconv"
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"strings"
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"time"
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"github.com/fatih/camelcase"
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"github.com/fatih/structs"
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)
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func newLoader(prefix string) *loader {
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return &loader{CamelCase: true, DefaultTagName: "default", Prefix: prefix}
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}
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// loader satisfies the loader interface. It parses a struct's field tags
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// and populates the each field with that given tag.
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type loader struct {
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// DefaultTagName is the default tag name for struct fields to define
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// default values for a field. Example:
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//
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// // Field's default value is "koding".
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// Name string `default:"koding"`
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//
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// The default value is "default" if it's not set explicitly.
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DefaultTagName string
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// Prefix prepends given string to every environment variable
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// {STRUCTNAME}_FIELDNAME will be {PREFIX}_FIELDNAME
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Prefix string
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// CamelCase adds a separator for field names in camelcase form. A
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// fieldname of "AccessKey" would generate a environment name of
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// "STRUCTNAME_ACCESSKEY". If CamelCase is enabled, the environment name
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// will be generated in the form of "STRUCTNAME_ACCESS_KEY"
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CamelCase bool
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}
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func (l *loader) getPrefix(s *structs.Struct) string {
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if l.Prefix != "" {
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return l.Prefix
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}
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return s.Name()
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}
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func (l *loader) Load(s interface{}) error {
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strct := structs.New(s)
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prefix := l.getPrefix(strct)
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if l.DefaultTagName == "" {
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l.DefaultTagName = "default"
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}
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for _, field := range structs.Fields(s) {
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if err := l.processTagField(l.DefaultTagName, field); err != nil {
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return err
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}
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if err := l.processEnvField(prefix, field); err != nil {
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return err
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}
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}
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return nil
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}
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// processTagField gets tagName and the field, recursively checks if the field has the given
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// tag, if yes, sets it otherwise ignores
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func (l *loader) processTagField(tagName string, field *structs.Field) error {
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switch field.Kind() {
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case reflect.Struct:
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for _, f := range field.Fields() {
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if err := l.processTagField(tagName, f); err != nil {
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return err
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}
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}
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default:
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defaultVal := field.Tag(l.DefaultTagName)
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if defaultVal == "" {
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return nil
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}
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err := fieldSet(field, defaultVal)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// processEnvField gets leading name for the env variable and combines the current
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// field's name and generates environment variable names recursively
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func (l *loader) processEnvField(prefix string, field *structs.Field) error {
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fieldName := l.getEnvFieldName(prefix, field.Name())
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switch field.Kind() {
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case reflect.Struct:
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for _, f := range field.Fields() {
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if err := l.processEnvField(fieldName, f); err != nil {
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return err
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}
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}
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default:
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v := os.Getenv(fieldName)
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if v == "" {
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return nil
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}
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if err := fieldSet(field, v); err != nil {
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return err
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}
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}
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return nil
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}
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// PrintEnvs prints the generated environment variables to the std out.
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func (l *loader) PrintEnvs(s interface{}) {
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strct := structs.New(s)
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prefix := l.getPrefix(strct)
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for _, field := range structs.Fields(s) {
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l.printEnvField(prefix, field)
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}
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}
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// printEnvField prints the field of the config struct for the flag.Usage
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func (l *loader) printEnvField(prefix string, field *structs.Field) {
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fieldName := l.getEnvFieldName(prefix, field.Name())
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switch field.Kind() {
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case reflect.Struct:
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for _, f := range field.Fields() {
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l.printEnvField(fieldName, f)
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}
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default:
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fmt.Printf(" %s (default value: '%s')\n", fieldName, field.Tag(l.DefaultTagName))
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}
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}
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// getEnvFieldName generates the field name combined with the prefix and the
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// struct's field name
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func (l *loader) getEnvFieldName(prefix string, name string) string {
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fieldName := strings.ToUpper(name)
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if l.CamelCase {
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fieldName = strings.ToUpper(strings.Join(camelcase.Split(name), "_"))
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}
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return strings.ToUpper(prefix) + "_" + fieldName
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}
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// fieldSet sets field value from the given string value. It converts the
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// string value in a sane way and is usefulf or environment variables or flags
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// which are by nature in string types.
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func fieldSet(field *structs.Field, v string) error {
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switch f := field.Value().(type) {
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case flag.Value:
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if v := reflect.ValueOf(field.Value()); v.IsNil() {
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typ := v.Type()
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if typ.Kind() == reflect.Ptr {
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typ = typ.Elem()
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}
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if err := field.Set(reflect.New(typ).Interface()); err != nil {
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return err
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}
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f = field.Value().(flag.Value)
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}
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return f.Set(v)
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}
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// TODO: add support for other types
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switch field.Kind() {
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case reflect.Bool:
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val, err := strconv.ParseBool(v)
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if err != nil {
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return err
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}
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if err := field.Set(val); err != nil {
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return err
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}
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case reflect.Int:
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i, err := strconv.Atoi(v)
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if err != nil {
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return err
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}
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if err := field.Set(i); err != nil {
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return err
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}
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case reflect.String:
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if err := field.Set(v); err != nil {
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return err
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}
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case reflect.Slice:
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switch t := field.Value().(type) {
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case []string:
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if err := field.Set(strings.Split(v, ",")); err != nil {
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return err
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}
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case []int:
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var list []int
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for _, in := range strings.Split(v, ",") {
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i, err := strconv.Atoi(in)
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if err != nil {
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return err
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}
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list = append(list, i)
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}
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if err := field.Set(list); err != nil {
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return err
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}
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default:
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return fmt.Errorf("multiconfig: field '%s' of type slice is unsupported: %s (%T)",
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field.Name(), field.Kind(), t)
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}
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case reflect.Float64:
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f, err := strconv.ParseFloat(v, 64)
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if err != nil {
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return err
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}
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if err := field.Set(f); err != nil {
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return err
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}
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case reflect.Int64:
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switch t := field.Value().(type) {
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case time.Duration:
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d, err := time.ParseDuration(v)
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if err != nil {
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return err
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}
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if err := field.Set(d); err != nil {
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return err
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}
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case int64:
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p, err := strconv.ParseInt(v, 10, 0)
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if err != nil {
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return err
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}
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if err := field.Set(p); err != nil {
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return err
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}
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default:
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return fmt.Errorf("multiconfig: field '%s' of type int64 is unsupported: %s (%T)",
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field.Name(), field.Kind(), t)
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}
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default:
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return fmt.Errorf("multiconfig: field '%s' has unsupported type: %s", field.Name(), field.Kind())
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}
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return nil
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}
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