sudo apt install apache2 certbot python3-certbot-apache

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

gamu.kr.conf
 
<VirtualHost *:443>
        ServerName  gamu.kr     ## 추가
        ServerAlias www.gamu.kr ## ServerAlias는 더 추가 가능 
 
        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/html
 
        ####### 중략 #######
        Include                /etc/letsencrypt/options-ssl-apache.conf     ## Certbot
        SSLCertificateFile     /etc/letsencrypt/live/gamu.kr/fullchain.pem  ## 추가한
        SSLCertificateKeyFile  /etc/letsencrypt/live/gamu.kr/privkey.pem    ## 부분
</VirtualHost>

sudo a2ensite gamu.kr.conf
sudo systemctl restart apache2

sudo certbot –apache   ## 실행후 질문에 선택사항 입력
sudo systemctl restart apache2
sudo systemctl status certbot.timer  ## 갱신 작동 확인

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

[Unit]
Description=gamu.kr & www.gamu.kr DDNS(DnsZi) Renewal Service
 
[Service]
Type=oneshot
ExecStart=/usr/local/bin/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

[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.kr     # 등록한 타이머 상태 확인