超簡単ubuntu20.04 + nginx + Let's Encrypt https初期設定

https初期設定（ubuntu20.04 + nginx + Let's Encrypt）

1. certbotインストール

$ sudo apt install certbot python3-certbot-nginx

2. certbot実行

$ sudo certbot --nginx -d <hostname>

# メールアドレス入力
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator nginx, Installer nginx
Enter email address (used for urgent renewal and security notices) (Enter 'c' to
cancel): <email address>

# ライセンス認証 
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Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf. You must
agree in order to register with the ACME server at
https://acme-v02.api.letsencrypt.org/directory
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(A)gree/(C)ancel: A

# メール共有
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Would you be willing to share your email address with the Electronic Frontier
Foundation, a founding partner of the Let's Encrypt project and the non-profit
organization that develops Certbot? We'd like to send you email about our work
encrypting the web, EFF news, campaigns, and ways to support digital freedom.
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(Y)es/(N)o: N

# 証明書を/etc/nginx/sites-enabled/myappへ格納
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for <hostname>
Waiting for verification...
Cleaning up challenges
Deploying Certificate to VirtualHost /etc/nginx/sites-enabled/myapp

# httpをhttpsへリダイレクト
Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
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1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
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Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Redirecting all traffic on port 80 to ssl in /etc/nginx/sites-enabled/myapp

# 成功すれば以下のメッセージ
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Congratulations! You have successfully enabled https://<hostname>

You should test your configuration at:
https://www.ssllabs.com/ssltest/analyze.html?d=<hostname>
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IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at:
  /etc/letsencrypt/live/<hostname>/fullchain.pem
  Your key file has been saved at:
  /etc/letsencrypt/live/<hostname>/privkey.pem
  Your cert will expire on 2021-03-21. To obtain a new or tweaked
  version of this certificate in the future, simply run certbot again
  with the "certonly" option. To non-interactively renew *all* of
  your certificates, run "certbot renew"
- Your account credentials have been saved in your Certbot
  configuration directory at /etc/letsencrypt. You should make a
  secure backup of this folder now. This configuration directory will
  also contain certificates and private keys obtained by Certbot so
  making regular backups of this folder is ideal.
- 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

3. certbot自動更新の確認

$ sudo systemctl status certbot.timer
$ sudo certbot renew --dry-run

以上、超簡単！

4. 参考

How To Secure Nginx with Let's Encrypt on Ubuntu 20.04 | DigitalOcean