Are there any settings for docker to block access to my website for specific country?
Or I need to do all programming myself? Is it optimal to create a block in .htaccess?
Or which 3rd party services to use. Preferably free, of course.
Yes. You can use a firewall like iptables to block the IP address blocks associated with a country. This process is not 100% as any users using a VPN outside their country, using a service like TOR or a web proxy outside their country would still be able to access your server since they would not be assigned an IP address associated with their country.
I found this guide that should be helpful.
This references blocking Chinese IPs and the script near the bottom uses a third party service to source the IP lists. These can be found here.
Found a solution - I had Prestashop, and just wanted to block specific country. Appeared it is native setting in Preferences→Geolocation