sudo apt install apache2 certbot python3-certbot-apache

sudo a2enmod ssl
sudo cp /etc/apache2/sites-available/{default-ssl,gamu.kr}.conf

<VirtualHost *:443>
	ServerName  gamu.kr     ## 추가
    ServerAlias www.gamu.kr ## ServerAlias는 더 추가 가능	
	
	ServerAdmin webmaster@localhost
	DocumentRoot /var/www/html

	ErrorLog ${APACHE_LOG_DIR}/error.log
	CustomLog ${APACHE_LOG_DIR}/access.log combined

	SSLEngine on

	SSLCertificateFile      /etc/ssl/certs/ssl-cert-snakeoil.pem
	SSLCertificateKeyFile   /etc/ssl/private/ssl-cert-snakeoil.key
	<FilesMatch "\.(?:cgi|shtml|phtml|php)$">
		SSLOptions +StdEnvVars
	</FilesMatch>
	<Directory /usr/lib/cgi-bin>
		SSLOptions +StdEnvVars
	</Directory>
</VirtualHost>

sudo a2ensite gamu.kr.conf
sudo systemctl restart apache2

sudo certbot --apache   ## 실행후 질문에 선택사항 입력. !!Double Dash!!
sudo systemctl restart apache2
sudo systemctl status certbot.timer  ## 갱신 작동 확인

다음과 같은 메세지 출력시에는

Unable to find corresponding HTTP vhost; 
Unable to create one as intended addresses conflict; 
Current configuration does not support automated redirection

이 방법으로 적용

certbot certonly --standalone -d gamu.kr,www.gamu.kr

/usr/lib/systemd/system/gamu.service 작성

[Unit]
Description=gamu.kr & www.gamu.kr DDNS(DnsZi) Renewal Service

[Service]
Type=oneshot
## DNSZi 사이트에서 코드 발행후 입력
ExecStart=$(type -p wget) -q -O - 'http://ddns.dnszi.com/set.html?user=<ddnzi-id>&auth=<dnszi-auth-key>&domain=gamu.kr&record='

/usr/lib/systemd/system/gamu.timer 작성

[Unit]
Description=Run DDNS(https://dnszi.com) Service Renewal twice daily

[Timer]
OnCalendar=*-*-* 00,12:00:00
RandomizedDelaySec=43200
Persistent=true

[Install]
WantedBy=timers.target

systemd 등록, 실행

sudo systemctl enable gamu.timer  # 부팅시 타이머 실행 설정
sudo systemctl start gamu.timer   # 타이머 실행
sudo systemctl status gamu     # 등록한 타이머 상태 확인