upstream dns-backend {
    server 127.0.0.1:8053;
    keepalive 30;
}
server {
        server_name dns.bentasker.co.uk;
        root /tmp/NOEXIST;
        location /dns-query {

                # Apply rate limiting
                limit_req zone=doh_limit burst=50 nodelay;

                # Process the IP to build a cache key
                set $ip_str $remote_addr;

                if ($ip_str ~ ([0-9,\.]*)\.([0-9]*)){
                        set $ip_str "$1.0/24";
                }


                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host $http_host;
                proxy_set_header X-NginX-Proxy true;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "";
                proxy_redirect off;
                proxy_set_header        X-Forwarded-Proto $scheme;
                proxy_read_timeout 86400;
                proxy_pass http://dns-backend/dns-query;


                # Include the client's /24 in the cache key
                proxy_cache doh-cache;
                proxy_cache_key https$host$request_uri|$ip_str;
                proxy_cache_valid  200 30s;
                proxy_ignore_headers X-Accel-Expires Expires Cache-Control Set-Cookie;

                # If two identical requests are received simnultaneously, make one wait
                proxy_cache_lock on;

        }


        location / {
            return 404;
        }

    listen 443 ssl http2; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/dns.bentasker.co.uk/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/dns.bentasker.co.uk/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}