openvpn client reload only nat rules instead of whole hotspot

conf/openvpn_90-hotspot

@@ -1,3 +1,29 @@
 #!/bin/bash
 
-systemctl restart __SERVICE_NAME__
+source /usr/share/yunohost/helpers
+
+is_nat_set() {
+  local gateway_interface=${1}
+  iptables -w -nvt nat -L POSTROUTING | grep MASQUERADE | grep -q "${gateway_interface}"
+}
+
+unset_nat() {
+  local gateway_interface=${1}
+  iptables -w -t nat -D POSTROUTING -o "${gateway_interface}" -j MASQUERADE
+}
+
+set_nat() {
+  local gateway_interface=${1}
+  iptables -w -t nat -A POSTROUTING -o "${gateway_interface}" -j MASQUERADE
+}
+
+old_gateway_interface=$(ynh_app_setting_get --app=$app --key=gateway_interface)
+new_gateway_interface=$(ip route get 1.2.3.4 | awk '{ print $5; }')
+
+if [[ -n "$old_gateway_interface" ]] && [[ "$old_gateway_interface" != "$new_gateway_interface" ]] && is_nat_set "$old_gateway_interface"; then
+  unset_nat "${old_gateway_interface}"
+fi
+
+set_nat "${new_gateway_interface}"
+
+ynh_app_setting_set --app=$app --key=gateway_interface --value="${new_gateway_interface}"

conf/ynh-hotspot

@@ -258,7 +258,7 @@ start)
         exit 1
     fi
 
-    echo "[hotspot] Starting..."
+    echo "[$app] Starting..."
     touch /tmp/.${service_name}-started
 
     # Check old state of the ipv4 NAT settings
@@ -295,13 +295,13 @@ start)
     start_dhcpd
 
     # Update dynamic settings
-    ynh_app_setting_set hotspot gateway_interface "${new_gateway_interface}"
+    ynh_app_setting_set --app=$app --key=gateway_interface --value="${new_gateway_interface}"
 
     # Regen-conf dnsmasq to enable dns resolution on dnsmasq for the new interface
     yunohost tools regen-conf dnsmasq
     ;;
 stop)
-    echo "[hotspot] Stopping..."
+    echo "[$app] Stopping..."
     rm -f /tmp/.${service_name}-started
 
     if ! is_other_hostapd_running; then