inside LXC container you can archieve it by installation of monit
apt-get install monit
then you have to edit /etc/monit/conf-enabled files and create particular files for services that you want to monitor and restart
then you can google monit openvpn example and adjust it somehow for your needs
example of monit config for openvpn but there are more on the net :
check process vpn-network with pidfile /var/run/vpn-network.pid
start program = “/etc/init.d/openvpn start vpn-network.com”
stop program = “/etc/init.d/openvpn stop vpn-network.com”
check host tap0 with address 1.1.1.1
start program = “/etc/init.d/openvpn start vpn-network.com”
stop program = “/etc/init.d/openvpn stop vpn-network.com”
if failed
icmp type echo count 5 with timeout 15 seconds
then restart
great thing you can also monitor other daemons and make sure monit restart them when necessary
also you can install monit into turris/openwrt by opkg install monit as it is part of turris packages and even I could not find example of monit config for LXC I suppose with a bit googling or experimenting also lxc should be monitored and restarted by monit
monit got web interface that can be accessed via login/password on http://your_lxc_container_ip:2812 by default or check status from ssh console via monit status command