add livereloading for rule config

Author: c-f

internal/runner/runner.go

@@ -42,6 +42,8 @@ func New(options *Options) (*Runner, error) {
 		if err != nil {
 			return nil, err
 		}
+		watchFile(r.options.RulesFile, serverTCP.LoadTemplate)
+
 		r.serverTCP = serverTCP
 		return &r, nil
 	}

internal/runner/watchdog.go

@@ -0,0 +1,36 @@
+package runner
+
+import (
+	"log"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+type WatchEvent func(fname string) error
+
+func watchFile(fname string, callback WatchEvent) (watcher *fsnotify.Watcher, err error) {
+	watcher, err = fsnotify.NewWatcher()
+	if err != nil {
+		return
+	}
+	go func() {
+		for {
+			select {
+			case event, ok := <-watcher.Events:
+				if !ok {
+					continue
+				}
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if err := callback(fname); err != nil {
+						log.Println("err", err)
+					}
+				}
+			case <-watcher.Errors:
+				// ignore errors for now
+			}
+		}
+	}()
+
+	err = watcher.Add(fname)
+	return
+}