Two domains with SSL on same nginx server - duplicate listen options for 443

Question

I've set up two web applications in my DigitalOcean droplet, and I'm trying to run both applications on different domains, with SSL encryption.

I can confirm that everything works if I only use one of the domains, and the error occurs when I try to run both at the same time.

nginx -t
duplicate listen options for [::]:443 in /etc/nginx/sites-enabled/hello.com:26

/etc/nginx/sites-avilable/hello.com

server {
    server_name hello.com www.hello.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;
    }

    listen [::]:443 ssl ipv6only=on default_server; # managed by Certbot
    listen 443 ssl default_server; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/hello.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/hello.com/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


}

server {
        if ($host = www.hello.com) {
                return 301 https://$host$request_uri;
        } # managed by Certbot


    if ($host = hello.com) {
            return 301 https://$host$request_uri;
    } # managed by Certbot


    listen 80 default_server;
    listen [::]:80 default_server;

    server_name hello.com www.hello.com;
    return 404; # managed by Certbot
}

/etc/nginx/sites-available/example.com

server {
    server_name example.com www.example.com;

    location / {
            proxy_pass http://localhost:3000;
            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;
    }

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com/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


}

server {
        if ($host = www.example.com) {
                return 301 https://$host$request_uri;
        } # managed by Certbot


    if ($host = example.com) {
            return 301 https://$host$request_uri;
    } # managed by Certbot


    listen 80;
    listen [::]:80;

    server_name example.com www.example.com;
    return 404; # managed by Certbot
}

What can I do to avoid this error? Further improvements in the nginx files are very much appreciated.

I've used the following guides:

How To Set Up Nginx Server Blocks: https://www.digitalocean.com/community/tutorials/how-to-set-up-nginx-server-blocks-virtual-hosts-on-ubuntu-14-04-lts

How To Set Up a Node.js Application for Production on Ubuntu 16.04: https://www.digitalocean.com/community/tutorials/how-to-set-up-a-node-js-application-for-production-on-ubuntu-16-04

How To Secure Nginx with Let's Encrypt on Ubuntu 16.04: https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-ubuntu-16-04

Answer 1

The problem is ipv6only=on, which can only be specified once according to the documentation.

The default value is on anyway, so the option can be safely removed.