server {
  listen 80;
  listen [::]:80 ipv6only=on;

  ...
}

server {
  listen 443;
  listen [::]:443 ipv6only=on;

  ...
}

server {
  listen 80 default_server;
  listen [::]:80 ipv6only=on;

  server_name localhost;

  root /var/www/http;
}