Better EPEL repository detection on RHEL and CentOS

[vutny]

Hi,

I had a problem with bootstrapping some CentOS machines were was pre-configured YUM repository which name contains "epel" substring, but that's not main Fedora's EPEL.

In such case script failed with very uninformative error:

         *  INFO: Running install_centos_stable_deps()
        Loaded plugins: fastestmirror


        Error getting repository data for epel, repository not found
         * ERROR: Failed to run install_centos_stable_deps()!!!

Providing more specific regex for grep fixes it.

P.S. I know this is kind of edge case, but somebody may fall into it as well.

[jfindlay]

@vutny, thanks for the pull request. When I do yum repolist I get !epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64 8,918, which doesn't look like it will be matched by your modified regex.

centos-7-main ~ master # yum repolist | grep -i '^epel/'
centos-7-main ~ master # yum repolist | grep -i 'epel/'
!epel/x86_64          Extra Packages for Enterprise Linux 7 - x86_64      8,918
centos-7-main ~ master #

[vutny]

Yeah, I got it also. (!) Exclamation mark from yum repolist command output means that repository metadata was expired.
By the way, this is the only one place in the script where hard-coded epel string is used. Everywhere else we have something similar to this command:

yum -y install ${package} --enablerepo=${_EPEL_REPO}

And this caused the error message for me before:

Error getting repository data for epel, repository not found

if the repo with exact name from $_EPEL_REPO variable was not configured. Another case, I've noticed that repo name would be epel-testing when I choose testing installation type on bootstrap.
All those cases are covered now.

The final improvement in my last commit is suppression of grep output with 'quiet' option instead of /dev/null redirection. It just looks more clear.

Thanks.

[jfindlay]

This is excellent, thanks, @vutny!

[sp1r]

Hello,

There is an issue with current grep pattern. Exclamation mark is optional in yum repolist output, and string without it does not match.

# yum repolist | grep '^[!]epel/'
# yum repolist  
...  
epel/7Server/x86_64                                         Extra Packages for RHEL Linux 7Server - x86_64                                     10,580
...

[vutny]

Ooops! Indeed, this should be

yum repolist | grep -q '^!\?'"${_EPEL_REPO}/"

Have I really wrote that? 😄
@sp1r Feel free to submit a PR to fix it!

[sp1r]

@vutny Thank you. I will be glad to join the contributors ;)