Simpler way to generate HTTPS self-signed certificates for local development

The simplest way to make locally-trusted certificates is to use mkcert, a simple zero-config tool.

Assuming a macOs machine, the process is the following:

Install mkcert:

brew install mkcert
brew install nss # required if we're using firefox

Install the local CA in the system trust store

mkcert -install

Generate the certicate for any names you'd like. Here I'm generating one for newsletter.local

mkcert -cert-file fullchain.pem -key-file privkey.pem newsletter.local

Point the new name to the local address in the hosts(/etc/hosts) file if it doesn't exist already

127.0.0.1 	localhost newsletter.local

fe80::1%lo0 	localhost
::1         	localhost

Here we're loading the certificates in nginx:

server{
    # ipv6
    listen [::]:443 ssl http2 ipv6only=on;
    # ipv4
    listen 443 ssl http2;
    server_name newsletter.local;

    ssl_certificate /var/www/newsletter.place/fullchain.pem; 
    ssl_certificate_key /var/www/newsletter.place/privkey.pem; 

    root /srv/newsletter.place/src/public; 

    index index.html;
    
}

Assuming everything was set up correctly we can now see that https://newsletter.local is now using a locally-trusted self-signed certificate, and it's valid for two years.