gitlab修改DNS解析配置文件

 在Linux （CentOS 7.9） 云服务器上解压 gitlab 时提示需要 Python 的环境

[root@rainyun-v1vct1jo src]# rpm -ivh gitlab-ce-10.8.4-ce.0.el7.x86_64.rpm 
warning: gitlab-ce-10.8.4-ce.0.el7.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID f27eab47: NOKEY
error: Failed dependencies:
	policycoreutils-python is needed by gitlab-ce-10.8.4-ce.0.el7.x86_64

yum 下载Python环境时，又提示镜像错误

[root@rainyun-v1vct1jo src]# sudo yum install policycoreutils-python
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
http://mirrors.aliyun.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.aliyun.com; Unknown error"
Trying other mirror.
http://mirrors.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.


 One of the configured repositories failed (CentOS-7 - Base - mirrors.aliyun.com),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=base ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable base
        or
            subscription-manager repos --disable=base

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=base.skip_if_unavailable=true

failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
http://mirrors.aliyun.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.aliyun.com; Unknown error"
http://mirrors.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.aliyuncs.com; Unknown error"
http://mirrors.cloud.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"

ping mirrors.aliyun.com 测试一下，出现域名无法解析的错误

ping: mirrors.aliyun.com: Name or service not known

需要检查并修复 /etc/resolv.conf 文件，添加可用的 DNS 服务器

vi /etc/resolv.conf

清空或修改内容为如下内容，使用阿里DNS

nameserver 223.5.5.5
nameserver 223.6.6.6