+
+func copyConfig(cfg *arvados.Config) *arvados.Config {
+ pr, pw := io.Pipe()
+ go func() {
+ err := json.NewEncoder(pw).Encode(cfg)
+ if err != nil {
+ panic(err)
+ }
+ pw.Close()
+ }()
+ cfg2 := new(arvados.Config)
+ err := json.NewDecoder(pr).Decode(cfg2)
+ if err != nil {
+ panic(err)
+ }
+ return cfg2
+}
+
+func watchConfig(ctx context.Context, logger logrus.FieldLogger, cfgPath string, prevcfg *arvados.Config, fn func()) {
+ watcher, err := fsnotify.NewWatcher()
+ if err != nil {
+ logger.WithError(err).Error("fsnotify setup failed")
+ return
+ }
+ defer watcher.Close()
+
+ err = watcher.Add(cfgPath)
+ if err != nil {
+ logger.WithError(err).Error("fsnotify watcher failed")
+ return
+ }
+
+ for {
+ select {
+ case <-ctx.Done():
+ return
+ case err, ok := <-watcher.Errors:
+ if !ok {
+ return
+ }
+ logger.WithError(err).Warn("fsnotify watcher reported error")
+ case _, ok := <-watcher.Events:
+ if !ok {
+ return
+ }
+ for len(watcher.Events) > 0 {
+ <-watcher.Events
+ }
+ loader := config.NewLoader(&bytes.Buffer{}, &logrus.Logger{Out: ioutil.Discard})
+ loader.Path = cfgPath
+ loader.SkipAPICalls = true
+ cfg, err := loader.Load()
+ if err != nil {
+ logger.WithError(err).Warn("error reloading config file after change detected; ignoring new config for now")
+ } else if reflect.DeepEqual(cfg, prevcfg) {
+ logger.Debug("config file changed but is still DeepEqual to the existing config")
+ } else {
+ logger.Debug("config changed, notifying supervisor")
+ fn()
+ prevcfg = cfg
+ }
+ }
+ }
+}