hns_doh_loadbalancer/nginx.conf

upstream loadbalancer {
    server doh.hnshosting.au:443 weight=1 max_fails=1 fail_timeout=30s;
    server easyhandshake.com:8053 weight=1 max_fails=1 fail_timeout=30s;
    server doh.hnsdns.com:443 weight=1 max_fails=1 fail_timeout=30s;
    server hs.dnssec.dev:443 weight=1 max_fails=1 fail_timeout=30s;
    server hnsns.net:443 weight=1 max_fails=1 fail_timeout=30s;
}

map $host $upstream {
    ~^doh\.hnshosting\.au$ doh.hnshosting.au;
    ~^easyhandshake\.com$ easyhandshake.com;
    ~^doh\.hnsdns\.com$ doh.hnsdns.com;
    ~^hs\.dnssec\.dev$ hs.dnssec.dev;
    ~^hnsns\.net$ hnsns.net;
}

server {
    listen 80;
    server_name _;

    location / {
        # Dynamically set the Host header based on the chosen upstream
        set $upstream_host "";

        if ($host ~* ^doh\.hnshosting\.au$) {
            set $upstream_host doh.hnshosting.au;
        }
        if ($host ~* ^easyhandshake\.com$) {
            set $upstream_host easyhandshake.com;
        }
        if ($host ~* ^doh\.hnsdns\.com$) {
            set $upstream_host doh.hnsdns.com;
        }
        if ($host ~* ^hs\.dnssec\.dev$) {
            set $upstream_host hs.dnssec.dev;
        }
        if ($host ~* ^hnsns\.net$) {
            set $upstream_host hnsns.net;
        }

        proxy_pass https://dynamic_upstream;
    }

    location @dynamic_upstream {
        # Use a named location to set proxy_pass dynamically
        proxy_pass https://$upstream_host;
        proxy_ssl_verify off;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        add_header X-Load-Balancer-Node $upstream_addr;
    }
}