Nginx configuration for domain, sub-domain and reverse proxy serup

wwwemirasgroup.conf.sh

# server blocks for incoming HTTP requests
# https://stackoverflow.com/questions/64955127/nginx-multiple-node-apps-with-multiple-subdomains
# https://stackoverflow.com/questions/5009324/node-js-nginx-what-now?noredirect=1&lq=1
server {
    listen 80;
    listen [::]:80;
    server_name emirasgroup.com www.emirasgroup.com;
    # redirect any HTTP request to HTTPS
    return 301 https://$http_host$request_uri;
}

server {
    # server block for 'sendmail.emirasgroup.com' domain
    listen 80;
    listen [::]:80;
    server_name sendmail.emirasgroup.com;

    location / {
        proxy_pass http://localhost:4000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

server {
    # server block for all the other requests
    # this block will be a default server block listening on port 80
    listen 80 default_server;
    listen [::]:80 default_server;
    # close the connection immediately
    return 444;
}

# server blocks for incoming HTTPS requests
server {
    listen [::]:443 ssl;
    listen 443 ssl;
    server_name emirasgroup.com www.emirasgroup.com;

    ssl_certificate     /home/ubuntu/ssl2021bundle.crt;
    ssl_certificate_key /home/ubuntu/ssl2021.key;
    access_log off;
    server_tokens off;
    error_log /tmp/log_nginx_err_wwwemirasgroupcom.log;

    location / {
        proxy_pass http://localhost:8000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}