Add DDNS support (#324)

* feat: add ddns updater framework

Note: no functionality implemented yet

* feat: add webhook ddns provider

* feat: update dashboard template

* fix: check nil and cron task string

* fix: webhook string formated with unexcepted param

* fix: webhook header split error

* feat: cloudflare ddns provider

* refract: move ddns update trigger into ReportSystemInfo

* lang: update other languages text

* fix: clear codes and logics

* fix: move update ddns to goroutine to avoid blocking

* fix: clear unused codes

* fix: update timestamp to prevent cache

service/singleton/singleton.go

@@ -1,6 +1,7 @@
 package singleton
 
 import (
+	"fmt"
 	"log"
 	"time"
 
@@ -46,6 +47,21 @@ func InitConfigFromPath(path string) {
 	if err != nil {
 		panic(err)
 	}
+	ValidateConfig()
+}
+
+// ValidateConfig 验证配置文件有效性
+func ValidateConfig() {
+	// 如果DDNS启用则检查Provider是否存在, 不存在直接退出
+	if Conf.DDNS.Enable {
+		_, err := GetDDNSProviderFromString(Conf.DDNS.Provider)
+		if err != nil {
+			panic(err)
+		}
+		if Conf.DDNS.MaxRetries < 1 || Conf.DDNS.MaxRetries > 10 {
+			panic(fmt.Errorf("DDNS.MaxRetries值域为[1, 10]的整数, 当前为 %d", Conf.DDNS.MaxRetries))
+		}
+	}
 }
 
 // InitDBFromPath 从给出的文件路径中加载数据库