Thanks to @廖雪峰 for the script
https://www.liaoxuefeng.com/article/0014189023237367e8d42829de24b6eaf893ca47df4fb5e000
#!/bin/sh
# create self-signed server certificate:
read -p "Enter your domain [www.example.com]: " DOMAIN
echo "Create server key..."
openssl genrsa -des3 -out $DOMAIN.key 1024
echo "Create server certificate signing request..."
SUBJECT="/C=US/ST=Mars/L=iTranswarp/O=iTranswarp/OU=iTranswarp/CN=$DOMAIN"
openssl req -new -subj $SUBJECT -key $DOMAIN.key -out $DOMAIN.csr
echo "Remove password..."
mv $DOMAIN.key $DOMAIN.origin.key
openssl rsa -in $DOMAIN.origin.key -out $DOMAIN.key
echo "Sign SSL certificate..."
openssl x509 -req -days 3650 -in $DOMAIN.csr -signkey $DOMAIN.key -out $DOMAIN.crt
echo "TODO:"
echo "Copy $DOMAIN.crt to /etc/nginx/ssl/$DOMAIN.crt"
echo "Copy $DOMAIN.key to /etc/nginx/ssl/$DOMAIN.key"
echo "Add configuration in nginx:"
echo "server {"
echo " ..."
echo " listen 443 ssl;"
echo " ssl_certificate /etc/nginx/ssl/$DOMAIN.crt;"
echo " ssl_certificate_key /etc/nginx/ssl/$DOMAIN.key;"
echo "}"