[bug] cannot ping www.baidu.com inside container since the dns doesn't work

[fuweid]

Ⅰ. Issue Description

I want to yum install something in contianer, but it always fails during update.
Try to ping the web site and it still fails

Ⅱ. Describe what happened

It seems that dns doesn't work.

This is log from pouchd.

INFO[2018-07-27T16:19:08.441250612+08:00] End of Calling POST /v1.24/containers/de4149/start, costs 552 ms. client @
DEBU[2018-07-27T16:19:14.86949067+08:00] Name To resolve: www.baidu.com.
DEBU[2018-07-27T16:19:14.870032089+08:00] [resolver] query www.baidu.com. (A) from 192.168.5.2:57648, forwarding to udp:10.0.2.3
DEBU[2018-07-27T16:19:18.87136515+08:00] [resolver] read from DNS server failed, read udp 192.168.5.2:57648->10.0.2.3:53: i/o timeout
DEBU[2018-07-27T16:19:19.881720123+08:00] Name To resolve: www.baidu.com.
DEBU[2018-07-27T16:19:19.881944046+08:00] [resolver] query www.baidu.com. (A) from 192.168.5.2:60755, forwarding to udp:10.0.2.3
DEBU[2018-07-27T16:19:23.882718424+08:00] [resolver] read from DNS server failed, read udp 192.168.5.2:60755->10.0.2.3:53: i/o timeout
DEBU[2018-07-27T16:19:24.902993006+08:00] Name To resolve: www.baidu.com.xx.yyy.com.
DEBU[2018-07-27T16:19:24.903270366+08:00] [resolver] query www.baidu.com.xx.yyy.com. (A) from 192.168.5.2:35746, forwarding to udp:10.0.2.3
DEBU[2018-07-27T16:19:28.904889835+08:00] [resolver] read from DNS server failed, read udp 192.168.5.2:35746->10.0.2.3:53: i/o timeout
DEBU[2018-07-27T16:19:29.908813492+08:00] Name To resolve: www.baidu.com.xx.yyy.com.
DEBU[2018-07-27T16:19:29.909107644+08:00] [resolver] query www.baidu.com.xx.yyy.com. (A) from 192.168.5.2:33135, forwarding to udp:10.0.2.3
DEBU[2018-07-27T16:19:33.909777218+08:00] [resolver] read from DNS server failed, read udp 192.168.5.2:33135->10.0.2.3:53: i/o timeout

$ sudo pouch run -it centos /bin/bash
[root@de41498b89cc /]# ping www.baidu.com
ping: www.baidu.com: Name or service not known
[root@de41498b89cc /]#

Ⅲ. Describe what you expected to happen

It should be ping successfully.

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. create container
2. ping www.baidu.com

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

$ sudo pouch version
KernelVersion:   4.4.0-130-generic
Os:              linux
Version:         1.0.0-rc1
APIVersion:      1.24
Arch:            amd64
BuildTime:       2018-07-27T11:06:18+08:00
GitCommit:       1.0.0.rc1-52-g8362c7b
GoVersion:       go1.9.1

[pouchrobot]

Thanks for your report, @fuweid
😱 This is a priority/P1 issue which is highest.
Seems to be severe enough.
ping @alibaba/pouch , PTAL.