146 lines
2.8 KiB
Go
146 lines
2.8 KiB
Go
package conf
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import (
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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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)
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func loadEnvInternal(env map[string]string, prefix string, rv reflect.Value) error {
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rt := rv.Type()
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if rt == reflect.TypeOf(time.Duration(0)) {
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if ev, ok := env[prefix]; ok {
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d, err := time.ParseDuration(ev)
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if err != nil {
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return fmt.Errorf("%s: %s", prefix, err)
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}
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rv.Set(reflect.ValueOf(d))
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}
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return nil
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}
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switch rt.Kind() {
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case reflect.String:
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if ev, ok := env[prefix]; ok {
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rv.SetString(ev)
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}
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return nil
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case reflect.Int:
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if ev, ok := env[prefix]; ok {
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iv, err := strconv.ParseInt(ev, 10, 64)
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if err != nil {
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return fmt.Errorf("%s: %s", prefix, err)
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}
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rv.SetInt(iv)
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}
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return nil
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case reflect.Uint64:
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if ev, ok := env[prefix]; ok {
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iv, err := strconv.ParseUint(ev, 10, 64)
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if err != nil {
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return fmt.Errorf("%s: %s", prefix, err)
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}
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rv.SetUint(iv)
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}
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return nil
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case reflect.Bool:
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if ev, ok := env[prefix]; ok {
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switch strings.ToLower(ev) {
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case "yes", "true":
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rv.SetBool(true)
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case "no", "false":
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rv.SetBool(false)
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default:
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return fmt.Errorf("%s: invalid value '%s'", prefix, ev)
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}
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}
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return nil
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case reflect.Slice:
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if rt.Elem().Kind() == reflect.String {
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if ev, ok := env[prefix]; ok {
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nv := reflect.Zero(rt)
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for _, sv := range strings.Split(ev, ",") {
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nv = reflect.Append(nv, reflect.ValueOf(sv))
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}
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rv.Set(nv)
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}
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return nil
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}
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case reflect.Map:
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for k := range env {
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if !strings.HasPrefix(k, prefix+"_") {
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continue
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}
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mapKey := strings.Split(k[len(prefix+"_"):], "_")[0]
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if len(mapKey) == 0 {
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continue
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}
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// allow only keys in uppercase
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if mapKey != strings.ToUpper(mapKey) {
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continue
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}
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// initialize only if there's at least one key
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if rv.IsNil() {
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rv.Set(reflect.MakeMap(rt))
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}
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mapKeyLower := strings.ToLower(mapKey)
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nv := rv.MapIndex(reflect.ValueOf(mapKeyLower))
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zero := reflect.Value{}
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if nv == zero {
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nv = reflect.New(rt.Elem().Elem())
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rv.SetMapIndex(reflect.ValueOf(mapKeyLower), nv)
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}
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err := loadEnvInternal(env, prefix+"_"+mapKey, nv.Elem())
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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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case reflect.Struct:
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flen := rt.NumField()
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for i := 0; i < flen; i++ {
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f := rt.Field(i)
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// load only public fields
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if f.Tag.Get("json") == "-" {
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continue
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}
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err := loadEnvInternal(env, prefix+"_"+strings.ToUpper(f.Name), rv.Field(i))
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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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return fmt.Errorf("unsupported type: %v", rt)
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}
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func loadFromEnvironment(prefix string, v interface{}) error {
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env := make(map[string]string)
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for _, kv := range os.Environ() {
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tmp := strings.SplitN(kv, "=", 2)
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env[tmp[0]] = tmp[1]
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}
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return loadEnvInternal(env, prefix, reflect.ValueOf(v).Elem())
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}
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