feat: if service can not found fqdn, replace fqdn with hostname (#1435)

Signed-off-by: Gaius <gaius.qi@gmail.com>

pkg/net/fqdn/fqdn.go

@@ -17,7 +17,11 @@
 package fqdn
 
 import (
+	"os"
+
 	"github.com/Showmax/go-fqdn"
+
+	logger "d7y.io/dragonfly/v2/internal/dflog"
 )
 
 var FQDNHostname string
@@ -29,9 +33,15 @@ func init() {
 // Get FQDN hostname
 func fqdnHostname() string {
 	fqdn, err := fqdn.FqdnHostname()
+	if err != nil {
+		logger.Warnf("can not found fqdn: %s", err.Error())
+		hostname, err := os.Hostname()
 		if err != nil {
 			panic(err)
 		}
 
+		return hostname
+	}
+
 	return fqdn
 }