도커 컨테이너를 이용해서 Let's Encrypt 인증서를 DNS-01 챌린지로 발급받고 자동 갱신하는 방법

도커 컨테이너를 이용해서 Let's Encrypt 인증서를 DNS-01 챌린지로 발급받고 자동 갱신하는 방법

Cloudflare API Token 생성

Cloudflare API Token

Certbot 공식 DNS 플러그인 이미지 사용

작업 디렉토리 생성

sudo mkdir -p /docker-container/certbot
cd /docker-container/certbot

1. Cloudflare credentials 정보 파일 생성

letsencrypt 디렉토리 생성

mkdir -p letsencrypt

Cloudflare API Token 설정

cat > letsencrypt/cloudflare.ini << EOF
# Cloudflare API Token
dns_cloudflare_api_token = YOUR_CLOUDFLARE_API_TOKEN_HERE
EOF

보안을 위해 파일 권한 제한

chmod 600 letsencrypt/cloudflare.ini

2. 초기 인증서 발급(docker run으로 한 번 실행)

인증서 발급 테스트(dry-run)

docker run -it --rm \
  --name certbot-initial \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/dns-cloudflare:latest \
  certonly \
  --dns-cloudflare \
  --dns-cloudflare-credentials /etc/letsencrypt/cloudflare.ini \
  --dns-cloudflare-propagation-seconds 60 \
  -d scbyun.com \
  -d "*.scbyun.com" \
  --email your@gmail.com \
  --agree-tos \
  --non-interactive \
  --dry-run  # 테스트 모드

인증서 발급

docker run -it --rm \
  --name certbot-initial \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/dns-cloudflare:latest \
  certonly \
  --dns-cloudflare \
  --dns-cloudflare-credentials /etc/letsencrypt/cloudflare.ini \
  --dns-cloudflare-propagation-seconds 60 \
  -d scbyun.com \
  -d "*.scbyun.com" \
  --email your@gmail.com \
  --agree-tos \
  --non-interactive \
  --preferred-challenges dns-01

발급 성공 메시지

Waiting 60 seconds for DNS changes to propagate

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/scbyun.com/fullchain.pem
Key is saved at:         /etc/letsencrypt/live/scbyun.com/privkey.pem
This certificate expires on 2026-05-12.
These files will be updated when the certificate renews.

NEXT STEPS:
- The certificate will need to be renewed before it expires. Certbot can automatically renew the certificate in the background, but you may need to take steps to enable that functionality. See https://certbot.org/renewal-setup for instructions.

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If you like Certbot, please consider supporting our work by:
 * Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
 * Donating to EFF:                    https://eff.org/donate-le
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인증서 파일 확인

s -l letsencrypt/live/scbyun.com

total 4
lrwxrwxrwx 1 root root  34 Feb 11 20:10 cert.pem -> ../../archive/scbyun.com/cert1.pem
lrwxrwxrwx 1 root root  35 Feb 11 20:10 chain.pem -> ../../archive/scbyun.com/chain1.pem
lrwxrwxrwx 1 root root  39 Feb 11 20:10 fullchain.pem -> ../../archive/scbyun.com/fullchain1.pem
lrwxrwxrwx 1 root root  37 Feb 11 20:10 privkey.pem -> ../../archive/scbyun.com/privkey1.pem
-rw-r--r-- 1 root root 692 Feb 11 20:10 README

3. 자동 갱신용 docker-compose.yml

cat > docker-compose.yml << 'EOF'
services:

  certbot:
    image: certbot/dns-cloudflare:latest
    container_name: certbot-renew
    restart: unless-stopped
    volumes:
      - ./letsencrypt:/etc/letsencrypt
    environment:
      # 갱신 체크 주기: 12시간마다
      - CERTBOT_RENEW_INTERVAL=12h
    command: >
      sh -c "
      while true; do
        certbot renew \
          --dns-cloudflare \
          --dns-cloudflare-credentials /etc/letsencrypt/cloudflare.ini \
          --dns-cloudflare-propagation-seconds 60 \
          --quiet \
          --deploy-hook 'echo Certificate renewed at \$(date)' &&
        sleep 43200;
      done
      "
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"
EOF

컨테이너 실행(백그라운드 실행)

docker compose up -d

컨테이너 상태 확인

docker compose ps

로그 확인

docker compose logs -f

4. 관리 명령어

인증서 정보 확인

docker run --rm \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/dns-cloudflare:latest \
  certificates

Saving debug log to /var/log/letsencrypt/letsencrypt.log

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Found the following certs:
  Certificate Name: scbyun.com
    Serial Number: 552ff06aa1188605d2a81b0b1a475fdbb6f
    Key Type: ECDSA
    Identifiers: scbyun.com *.scbyun.com
    Expiry Date: 2026-05-12 10:11:38+00:00 (VALID: 89 days)
    Certificate Path: /etc/letsencrypt/live/scbyun.com/fullchain.pem
    Private Key Path: /etc/letsencrypt/live/scbyun.com/privkey.pem
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수동 갱신

docker run --rm \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/dns-cloudflare:latest \
  renew \
  --dns-cloudflare \
  --dns-cloudflare-credentials /etc/letsencrypt/cloudflare.ini \
  --force-renewal

인증서 폐기

docker run --rm \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/dns-cloudflare:latest \
  revoke \
  --cert-path /etc/letsencrypt/live/scbyun.com/cert.pem \
  --delete-after-revoke

인증서 백업

tar -czf certbot-backup-$(date +%Y%m%d).tar.gz letsencrypt/