使用 Certbot 工具来生成一个泛域名证书

以 Ubuntu 为例，使用以下命令进行安装Certbot

sudo apt update
sudo apt install certbot

生成泛域名证书"*.example.com"

sudo certbot certonly --manual --preferred-challenges=dns -d "*.example.com"

参数说明：

--manual：手动模式，需要手动添加 DNS TXT 记录。
--preferred-challenges=dns：指定使用DNS-01验证域名。
-d "*.example.com"：指定泛域名或单域名。

# certbot certonly --manual --preferred-challenges=dns -d "*.example.com"
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator manual, Installer None
Enter email address (used for urgent renewal and security notices) (Enter 'c' to
cancel): test@example.com

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Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.4-April-3-2024.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

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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.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
(Y)es/(N)o: Y
Obtaining a new certificate
Performing the following challenges:
dns-01 challenge for example.com

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NOTE: The IP of this machine will be publicly logged as having requested this
certificate. If you're running certbot in manual mode on a machine that is not
your server, please ensure you're okay with that.

Are you OK with your IP being logged?
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(Y)es/(N)o: Y

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Please deploy a DNS TXT record under the name
_acme-challenge.example.com with the following value:

hyyI-h8Ct1SCB2tArLnRCbeYvzhNfKvetONPOb_hc3k

Before continuing, verify the record is deployed.
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Press Enter to Continue
Waiting for verification...
Cleaning up challenges

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/example.com/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/example.com/privkey.pem
   Your cert will expire on 2024-11-10. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"
 - 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

验证成功后，Certbot 会在 /etc/letsencrypt/live/ 目录下生成证书和密钥文件。

在nginx中使用证书

server {
    listen 443 ssl;
    server_name *.example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;

    # 其他配置
}

证书有效期为3个月，到期会自动更新证书，证书更新后重新加载nginx配置。
进入/etc/letsencrypt/renewal-hooks/deploy目录，新建reload-nginx.sh文件，添加执行权限sudo chmod +x reload-nginx.sh。
添加nginx重启脚本

#!/bin/bash

# 重载Nginx配置
systemctl reload nginx