申请 Let’s Encrypt 通配符 HTTPS 证书

Let’s Encrypt 是 ISRG （Internet Security Research Group）提供的一个免费、开放、自动化的证书签发服务。

下载 Certbot

使用 wget 命令下载 certbot 客户端

由于 Let’s Encrypt 的有效期是 90 天，到期后我们需要对证书进行续签，因此每隔一段时间就需要使用到这个工具，所有建议将这个工具下载到 /sbin 目录。

1	wget https://dl.eff.org/certbot-auto -O /sbin/certbot-auto

设为可执行权限
1
chmod a+x /sbin/certbot-auto

申请证书

使用 Certbot 申请通配符证书

1 2	# 注xxx.com请根据自己的域名自行更改 /sbin/certbot-auto certonly -d *.newyingyong.cn --manual --preferred-challenges dns --server https://acme-v02.api.letsencrypt.org/directory

certonly，表示安装模式，Certbot 有安装模式和验证模式两种类型的插件。
–manual 表示手动安装插件，Certbot 有很多插件，不同的插件都可以申请证书，用户可以根据需要自行选择
-d 为那些主机申请证书，如果是通配符，输入 *.newyingyong.cn（可以替换为你自己的域名）
–preferred-challenges dns，使用 DNS 方式校验域名所有权
–server，Let’s Encrypt ACME v2 版本使用的服务器不同于 v1 版本，需要显示指定。

提示输入您的邮箱地址

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):

输入 A 同意 Let’s Encrypt 协议

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
-------------------------------------------------------------------------------
(A)gree/(C)ancel:

输入 Y 对域名和机器（IP）进行绑定

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?
-------------------------------------------------------------------------------
(Y)es/(N)o:

要求配置 DNS TEXT 记录，从而校验域名所有权

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

2_8KBE_jXH8nYZ2unEViIbW52LhIqxkg6i9mcwsRvhQ

Before continuing, verify the record is deployed.
-------------------------------------------------------------------------------
Press Enter to Continue

添加完解析后，稍等1分钟，按回车执行。如果证书申请成功，提示如下信息：

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/whai.me/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/whai.me/privkey.pem
   Your cert will expire on 2018-06-12. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot-auto
   again. To non-interactively renew *all* of your certificates, run
   "certbot-auto 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

设置自动更新

Let’s Encrypt 的单次授权有效时间为 90 天。
所以我们需要设置自动更新授权，在其没过期之前更新一遍。
命令行运行以下命令：

1	certbot-auto renew

会输出类似：

$ certbot-auto renew
Saving debug log to /var/log/letsencrypt/letsencrypt.log

-------------------------------------------------------------------------------
Processing /etc/letsencrypt/renewal/tiicle.com.conf
-------------------------------------------------------------------------------
Cert not yet due for renewal

The following certs are not due for renewal yet:
  /etc/letsencrypt/live/tiicle.com/fullchain.pem (skipped)
No renewals were attempted.

certbot-auto renew 命令会读取所有 /etc/letsencrypt/renewal 目录下的配置信息，遍历检查每一个授权域名是否离过期时间只有 30 天，如果是的话，执行更新。因为我们才刚刚授权过，所以如以上显示的，skipped 跳过了。

renew 命令自带了判断机制，我们可以放心地把它放到 cron 里去每日执行。

1	sudo crontab -e

增加以下内容：

1 2	30 2 * * * /usr/local/sbin/certbot-auto renew >> /var/log/le-renew.log 35 2 * * * /etc/init.d/nginx reload

这样就能每日检查，并保证 HTTPS 授权不过期。