event system

src/config.go

@@ -3,7 +3,9 @@ package main
 import (
 	"fmt"
 
+	"git.openpdu.org/OpenPDU/openpdu/events"
 	"git.openpdu.org/OpenPDU/openpdu/syslog"
+	"github.com/fsnotify/fsnotify"
 	"github.com/spf13/viper"
 )
 
@@ -16,4 +18,10 @@ func init() {
 	if err != nil {                      // Handle errors reading the config file
 		syslog.Err(fmt.Sprintf("Can't read config file: %s \n", err.Error()))
 	}
+	viper.WatchConfig()
+	viper.OnConfigChange(func(e fsnotify.Event) {
+		//The Viper configuration has changed to perform the responding operation
+		fmt.Println("Config file changed:", e.Name)
+		events.FireEvent("config_changed")
+	})
 }

src/events/events.go

@@ -0,0 +1,28 @@
+package events
+
+var handlers map[string][]func()
+
+func init() {
+	handlers = make(map[string][]func())
+}
+
+func AddListener(event string, f func()) {
+	l, isPresent := handlers[event]
+	if !isPresent {
+		handlers[event] = []func(){
+			f,
+		}
+	} else {
+		handlers[event] = append(l, f)
+	}
+}
+
+func FireEvent(event string) {
+	l, isPresent := handlers[event]
+	if !isPresent {
+		return
+	}
+	for _, v := range l {
+		v()
+	}
+}

src/go.mod

@@ -12,6 +12,7 @@ require (
 	golang.org/x/image v0.0.0-20201208152932-35266b937fa6
 	gopkg.in/macaron.v1 v1.4.0
 	periph.io/x/periph v3.6.7+incompatible
+	github.com/fsnotify/fsnotify v1.4.7
 )
 
 replace git.openpdu.org/OpenPDU/openpdu => ./src

src/ups/ups.go

@@ -1,6 +1,7 @@
 package ups
 
 import (
+	"git.openpdu.org/OpenPDU/openpdu/events"
 	"git.openpdu.org/OpenPDU/openpdu/syslog"
 	nut "github.com/robbiet480/go.nut"
 	"github.com/spf13/viper"
@@ -10,11 +11,18 @@ var upsClient nut.Client
 var ups nut.UPS
 var Vars map[string]nut.Variable
 
+var defaults = map[string]interface{}{
+	"Ups.Host":     "localhost",
+	"Ups.Name":     "ups",
+	"Ups.Username": "",
+	"Ups.Password": "",
+}
+
 func init() {
-	viper.SetDefault("Ups.Host", "localhost")
-	viper.SetDefault("Ups.Name", "ups")
-	viper.SetDefault("Ups.Username", "")
-	viper.SetDefault("Ups.Password", "")
+	for k, v := range defaults {
+		viper.SetDefault(k, v)
+	}
+	events.AddListener("config_changed", Reconfigure)
 }
 
 func UpsConnect() {
@@ -51,6 +59,7 @@ func UpsConnect() {
 		if u.Name == viper.GetString("Ups.Name") {
 			ups = u
 			syslog.Notice("UPS connected")
+			events.FireEvent("ups_connected")
 			UpsReadVars()
 		}
 	}
@@ -67,5 +76,6 @@ func Reconfigure() {
 	ups = nut.UPS{}
 	upsClient = nut.Client{}
 	syslog.Notice("UPS disconnected")
+	events.FireEvent("ups_disconnected")
 	go UpsConnect()
 }