How to implement restriction of access to a personal web resource?

Question

Access rights

For personal purposes, a small site has been raised on the VPS, there are no rights or any restrictions on this application. The application is spinning in the docker, the docker is on ubuntu.
At the moment, the application simply looks to the external network and anyone can enter. How to properly restrict access so that accessibility is only from personal devices?

Answer 1

IPTABLES, access only private ip

Answer 2

Or set up a firewall on the vps server to restrict access from a personal ip address (it must be static), usually a firewall in linux based on iptables, but there are corresponding items in the administration panel (for example, Amazon).
Restrictions on the ip address of the client are also configured on the web server itself, usually it is easier than a firewall.
Either (if, for example, the personal ip address is dynamic) set up the server on a local network for the vps server (or localhost) and set up port forwarding (for example, using ssh) or raise a vpn connection (vps and your local network are connected to someone else's vpn or set up vpn server on vps)
Or, the simplest, configure authentication using a web server on vps, basic auth is configured in a couple of lines in the config:
https://docs.nginx.com/nginx/admin-guide/security-...
https://httpd.apache.org/docs/2.4/howto/auth.html
basic auth will ask the browser once for the first time access, when you close the page and reopen it will ask for a password again.