CentOS mirrorlist导致的OpenStack 镜像制作失败

前段时间参考如下方法做了一个Centos6.4的镜像很顺利：

https://github.com/globocom/references/wiki/Building-a-CentOS-6.2-image-for-openstack  [1]

其实顺利的原因在于6.4是目前版本最新的CentOS。相信当时那个作者写那篇文档的时候，最新的版本是6.2.

在完成Install the OS这一步时，[1]中是先装了centos-release-6-3.el6.centos.9.x86_64.rpm，这个包初始化了yum需要的repository.

初始化之后的repo配置文件在/mnt/centos-image/etc/yum.repos.d/下面，其中CentOS-Base.repo内容大致如下：

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
#

[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 
[updates]
name=CentOS-$releasever - Updates
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
#baseurl=http://mirror.centos.org/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

其中的mirrorlist是这样的一个url:

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os

其中的$releasever是6.2、6之类的CentOs版本号,  basearch是x86_64之类的。

在浏览器中访问：

http://mirrorlist.centos.org/?release=6.2&arch=x86_64&repo=os

返回了6.2 is not a valid release or hasnt been released yet。这个结果显然是无效的。

访问http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os

返回了：

http://mirror.neu.edu.cn/centos/6.4/os/x86_64/
http://mirrors.hust.edu.cn/centos/6.4/os/x86_64/
http://mirrors.grandcloud.cn/centos/6.4/os/x86_64/
http://mirrors.163.com/centos/6.4/os/x86_64/
http://mirrors.tuna.tsinghua.edu.cn/centos/6.4/os/x86_64/
http://mirrors.hustunique.com/centos/6.4/os/x86_64/
http://centos.ustc.edu.cn/centos/6.4/os/x86_64/
http://mirror.esocc.com/centos/6.4/os/x86_64/
http://mirrors.btte.net/centos/6.4/os/x86_64/
http://mirror.bit.edu.cn/centos/6.4/os/x86_64/

这个是CentOS6.4，也就是目前最新版本的mirrorlist。这就说明如果不改掉repo文件，安装系统时，是从CentOS6.4的源上下载包和依赖的，那么装出来的一定是最新CentOS 6的版本。

如果想在系统镜像中装CentOS6.2的系统，那么必须在安装系统之前将repo文件改掉。

可以在本地网络自己建一个源。参考http://blog.csdn.net/bhq2010/article/details/9237727