[root]# wget http://nginx.org/download/nginx-1.12.0.tar.gz
[root]# tar zxvf nginx-1.12.0.tar.gz
[root]# cd nginx-1.12.0
[root]# ./configure --prefix=/usr/local/nginx --with-http_ssl_module \
--with-openssl=./openssl-1.0.1e \
--with-openssl-opt="enable-tlsext"

[root]# wget https://nchc.dl.sourceforge.net/project/pcre/pcre/8.35/pcre-8.35.tar.gz
[root]# tar zxvf pcre-8.35
[root]# yum -y install gcc
[root]# yum -y install gcc-c++
[root]# yum install -y zlib-devel

[root]# ./configure --prefix=/usr/local/nginx --with-http_ssl_module \
--with-openssl=./openssl-1.0.1e \
--with-openssl-opt="enable-tlsext" \
--with-pcre=./pcre-8.35

  ...
  server {
    listen    443 ssl;
    listen    [::]:443 ssl;
    server_name abc.com;
    root     /usr/share/nginx/html;

    ssl_certificate "/root/keys/abc.com.pem";
    ssl_certificate_key "/root/keys/abc.com.private.pem";
    include /etc/nginx/default.d/*.conf;

    location / {
    }
    error_page 404 /404.html;
      location = /40x.html {
    }
    error_page 500 502 503 504 /50x.html;
      location = /50x.html {
    }
  }

  server {
    listen    443 ssl;
    listen    [::]:443 ssl;
    server_name def.com;
    root     /usr/share/nginx/html;

    ssl_certificate "/root/keys/def.com.pem";
    ssl_certificate_key "/root/keys/def.com.private.pem";
    include /etc/nginx/default.d/*.conf;

    location / {
    }
    error_page 404 /404.html;
      location = /40x.html {
    }
    error_page 500 502 503 504 /50x.html;
      location = /50x.html {
    }
  }

[root]# yum install -y epel-releasesudo 
[root]# yum install -y certbot

server {
   listen    80 default_server;

   ...

  location ^~ /.well-known/acme-challenge/ {  
    default_type "text/plain";  
    root   /usr/share/nginx/html;
  }

  location = /.well-known/acme-challenge/ {  
    return 404;
  }
}

[root]# certbot certonly --webroot -w /usr/share/nginx/html/ -d your.domain.com

|-- fullchain.pem 
|-- privkey.pem

server {
  listen    443 ssl;
  listen    [::]:443 ssl;
  server_name def.com;
  root     /usr/share/nginx/html;

  ssl_certificate "/etc/letsencrypt/live/your.domain.com/fullchain.pem";
  ssl_certificate_key "/etc/letsencrypt/live/your.domain.com/privkey.pem";
  include /etc/nginx/default.d/*.conf;

  location / {
  }
  error_page 404 /404.html;
    location = /40x.html {
  }
  error_page 500 502 503 504 /50x.html;
    location = /50x.html {
  }
}

certbot renew --dry-run

[root]# crontab -e
30 2 * * 1 /usr/bin/certbot renew >> /var/log/le-renew.log