网站设置免费letsencrypt HTTPS 证书以及配置nginx的https

给网站安装免费letsencrypt HTTPS 证书,配置nginx的https
letsencrypt 提供免费证书，有效期为90天。
过期后可以重新生成，相当于可以一直免费
letsencrypt网站
下面通过certbot 生成证书

1.下载certbot，并解压

wget https://codeload.github.com/certbot/certbot/zip/master

2.生成证书

./certbot-auto certonly --standalone --agree-tos -d example.com -d www.example.com

错误：
Problem binding to port 80: Could not bind to IPv4 or IPv6.
关闭服务器(nginx)之后再执行，即可解决
3.更新已过期证书

certbot renew --dry-run
./certbot-auto renew

注：（更新时问题）
Upgrading certbot-auto 0.40.1 to 1.2.0...
Couldn't download https://raw.githubusercontent.com/certbot/certbot/v1.2.0/letsencrypt-auto-source/letsencrypt-auto. <urlopen error [Errno 111] Connection refused>
可将其锁定到特定版本并且不接收自动更新，只需在命令后加 --no-self-upgrade 即可。即

./certbot-auto renew --no-self-upgrade

4.修改nginx配置

server {
......
listen  443 ssl;
ssl_certificate      /etc/letsencrypt/live/xxxxxx.com/fullchain.pem;
ssl_certificate_key  /etc/letsencrypt/live/xxxxxx.com/privkey.pem;
......
}
server {
        listen  80;
        server_name xxxxxx.com;
        return 301 https://$host$request_uri;
}