官网地址：https://certbot.eff.org/
本文主要是介绍配置Nignx的证书，做了一些关键步骤的记录，其实官网已经非常详细，所以大家最好参考官网。

1、安装相关工具

[root@online nginx]# yum -y install yum-utils

2、安装certbot

[root@online nginx]# yum install certbot python2-certbot-nginx

3、如果第二步安装成功，就跳过下面，下面主要是介绍Python报的一些问题，需要用下面两条命令解决

[root@online nginx]# pip install requests urllib3 pyOpenSSL --force --upgrade

[root@online nginx]# pip install --upgrade --force-reinstall 'requests==2.6.0'

4、生成证书过程

[root@online nginx]# certbot --nginx --nginx-server-root=/usr/local/nginx/conf/
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): xxxxx@qq.com #填写自己邮箱地址
Starting new HTTPS connection (1): acme-v02.api.letsencrypt.org

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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 #同意

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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: Y #Yes
Starting new HTTPS connection (1): supporters.eff.org

Which names would you like to activate HTTPS for?
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1: www.xxxx.com
2: www.yyyy.com
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Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 1 #选项对应域名的编号
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for dev.online.qsyuwen.cn
Waiting for verification...
Cleaning up challenges
Resetting dropped connection: acme-v02.api.letsencrypt.org
Deploying Certificate to VirtualHost /usr/local/nginx/conf/vhost/dev.online.api.conf

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): 1 #是否跳转

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Congratulations! You have successfully enabled https://dev.online.qsyuwen.cn

You should test your configuration at:
https://www.ssllabs.com/ssltest/analyze.html?d=dev.online.qsyuwen.cn
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IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/dev.online.qsyuwen.cn/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/dev.online.qsyuwen.cn/privkey.pem
   Your cert will expire on 2019-08-19. 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