檢查Ubuntu是否設定了DNS，確保解析正常

Ubuntu DNS配置方法

interfaces方式
修改/etc/network/interfaces，配置DNS需要在該檔案中加入

dns-nameserver xx.xx.xx.xx
dns-nameserver xxx.xxx.xx.xx
dns-nameservers xxx.xxx.xxx.xxx xxx.xxx.xx.xxx

•dns-nameserver: 指定一條DNS地址，如果需要指定多個DNS則需要使用新增多行。
•dns-nameservers: 指定多個DNS地址，用空格隔開。
需要重啟電腦方可生效

resolvconf方式

nameserver xxx.xxx.xx.xxx
nameserver xx.xx.xx.xx

•nameserver: 指定DNS地址，當有多個DNS記錄時每個DNS記錄佔一行。

sudo resolvconf -u      #更新/etc/resolv.conf檔案

Ubuntu 更換國內源

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak1

更換源為阿里源

sudo gedit /etc/apt/sources.list
 


deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse  
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse  
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse  
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse  
deb http://mirrors.aliyun
 
.com/ubuntu/ trusty-backports main restricted universe multiverse  
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse  
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse  
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse  
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse  
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe
multiverse

更新源

sudo apt-get update

這時候你會發現docker pull正常了~