[Trouble Shooting] CentOs Could not retrieve mirrorlist

문제 발생

Docker를 학습하기 위해 CentOs7 Base Container에서 추가 환경 설정을 하는 도중에 발생했다.

환경 AWS Linux 2

docker run --name centos --it centos:7
yum install -y httpd curl

Container Build를 하려고 centos7 위에 apache web server와 curl을 설치하는데 아래와 같은 에러가 발생한다.

Loaded plugins: fastestmirror, ovl
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=container error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"


 One of the configured repositories failed (Unknown),
 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=<repoid> ...

     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 <repoid>
        or
            subscription-manager repos --disable=<repoid>

     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=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64

문제 원인 분석

핵심 키워드는 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=container error was 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error" 이 부분인 것 같다.

바로 이 부분을 검색했다.
해당 문제는 CentOs7에서 yum central repository 주소를 변경한 것 이었다.

문제 해결

sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

1. 처음 설치한 경우 CentOS 관련 파일에 작성된 모든 mirrorlist 정보들을 주석으로 처리한다.
2. central repository 주소를 vault.centos로 수정한다. 여기는 과거 centos 정보들을 아카이빙 하는 곳이다.

이 방법은 CentOS7 뿐만 아니라 다른 버전에서도 같은 문제가 발생 시 해결할 수 있다.

참고

https://developer-woong.tistory.com/112