Installing an SSL certificate is very simple. One drawback of having the server directly issue a certificate is that it is only valid for three months per issuance. It is recommended that if you are using domestic cloud providers, you log in directly to the backend, go to the domain center, and apply for an SSL certificate. Applying once can ensure it lasts for a year without needing to be touched.

The steps for the server to issue an SSL certificate are as follows:

1. Install the certificate issuing client: apt install Certbot

2. Execute: certbot --nginx -d abc.com -d www.abc.com # Replace abc.com with your domain name.

3. If the following error is reported:

Error message

# certbot --nginx
Saving debug log to /var/log/letsencrypt/letsencrypt.log
The requested nginx plugin does not appear to be installed

Solution

sudo apt install python3-certbot-nginx

Then re-execute

certbot --nginx -d abc.com -d www.abc.com 

Follow the prompts to enter your email, agree to the statement, and finally fill in whether to update the current certificate location in the nginx configuration file.