mirror of
https://github.com/bluenviron/mediamtx
synced 2024-12-13 10:14:58 +00:00
197 lines
4.0 KiB
Go
197 lines
4.0 KiB
Go
// Package env contains a function to load configuration from environment.
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package env
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import (
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"encoding/json"
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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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)
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type envUnmarshaler interface {
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UnmarshalEnv(string) error
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}
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func envHasAtLeastAKeyWithPrefix(env map[string]string, prefix string) bool {
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for key := range env {
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if strings.HasPrefix(key, prefix) {
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return true
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}
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}
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return false
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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 i, ok := rv.Addr().Interface().(envUnmarshaler); ok {
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if ev, ok := env[prefix]; ok {
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err := i.UnmarshalEnv(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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}
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return nil
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}
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switch rt {
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case reflect.TypeOf(""):
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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.TypeOf(int(0)):
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if ev, ok := env[prefix]; ok {
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iv, err := strconv.ParseInt(ev, 10, 32)
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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.TypeOf(uint64(0)):
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if ev, ok := env[prefix]; ok {
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iv, err := strconv.ParseUint(ev, 10, 32)
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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.TypeOf(float64(0)):
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if ev, ok := env[prefix]; ok {
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iv, err := strconv.ParseFloat(ev, 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.SetFloat(iv)
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}
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return nil
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case reflect.TypeOf(bool(false)):
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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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}
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switch rt.Kind() {
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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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if unm, ok := nv.Interface().(json.Unmarshaler); ok {
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unm.UnmarshalJSON(nil) // load defaults
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}
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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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case reflect.Slice:
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if rt.Elem() == reflect.TypeOf("") {
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if ev, ok := env[prefix]; ok {
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if ev == "" {
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rv.Set(reflect.MakeSlice(rv.Type(), 0, 0))
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} else {
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rv.Set(reflect.ValueOf(strings.Split(ev, ",")))
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}
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}
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return nil
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}
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if rt.Elem().Kind() == reflect.Struct {
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if ev, ok := env[prefix]; ok && ev == "" { // special case: empty list
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rv.Set(reflect.MakeSlice(rv.Type(), 0, 0))
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} else {
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for i := 0; ; i++ {
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itemPrefix := prefix + "_" + strconv.FormatInt(int64(i), 10)
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if !envHasAtLeastAKeyWithPrefix(env, itemPrefix) {
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break
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}
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elem := reflect.New(rt.Elem())
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err := loadEnvInternal(env, itemPrefix, elem.Elem())
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if err != nil {
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return err
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}
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rv.Set(reflect.Append(rv, elem.Elem()))
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}
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}
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return nil
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}
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}
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return fmt.Errorf("unsupported type: %v", rt)
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}
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// Load loads the configuration from the environment.
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func Load(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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