获取Docker IP，找到 Docker0 对应的IP

$ ifconfig

结果如下， 172.17.0.1 就是我们要的IP

docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255
        ether 02:42:70:c3:4b:fd  txqueuelen 0  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

编辑虚拟主机配置，配置 proxy_pass 即可。这样就可以使用Nginx容器反向代理到宿主机上的服务。

location /
    {
        proxy_pass http://172.17.0.1:3000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header REMOTE-HOST $remote_addr;
        add_header X-Cache $upstream_cache_status;
        expires 12h;
    }