Red Hat System Administration I

Objectives

After completing this section, students should be able to enable and disable the use of Red Hat or third-party yum repositories.

Enabling Red Hat software repositories

Registering a system to the subscription management service automatically configures access to software repositories based on the attached subscriptions. To view all available repositories:

[root@serverX ~]# yum repolist all
Loaded plugins: langpacks
repo id                                    repo name                                        status
rhel-7-server-debug-rpms/7Server/x86_64    Red Hat Enterprise Linux 7 Server (Debug RPMs)   disabled
rhel-7-server-rpms/7Server/x86_64          Red Hat Enterprise Linux 7 Server (RPMs)         enabled: 5,071
rhel-7-server-source-rpms/7Server/x86_64   Red Hat Enterprise Linux 7 Server (Source RPMs)  disabled
repolist: 5,071

Enable and disable repositories with yum-config-manager. This will change the enabled parameter in the /etc/yum.repos.d/redhat.repo file.

[root@serverX ~]# yum-config-manager --enable rhel-7-server-debug-rpms
Loaded plugins: langpacks
===================== repo: rhel-7-server-debug-rpms ======================
[rhel-7-server-debug-rpms]
async = True
bandwidth = 0
base_persistdir = /var/lib/yum/repos/x86_64/7Server
baseurl = https://cdn.redhat.com/content/dist/rhel/server/7/7Server/x86_64/debug
cache = 0
cachedir = /var/cache/yum/x86_64/7Server/rhel-7-server-debug-rpms
check_config_file_age = True
cost = 1000
deltarpm_percentage = 
enabled = 1
...

Enabling third-party software repositories

Third-party repositories are directories of software package files provided by a non-Red Hat source, which can be accessed by yum from a website, FTP server, or local file system. Yum repositories are used by non-Red Hat distributors of software, or for small collections of local packages. (For example, Adobe provides some of its free software for Linux through a yum repository.) The content.example.com classroom server actually hosts yum repositories for this class.

Put a file in the /etc/yum.repos.d/ directory to enable support for a new third-party repository. Repository configuration files must end in .repo. The repository definition contains the URL of the repository, a name, whether to use GPG to check the package signatures, and if so, the URL pointing to the trusted GPG key.

Using yum-config-manager

If the URL for a yum repository is known, a configuration file can be created with yum-config-manager.

[root@serverX ~]# yum-config-manager --add-repo="http://dl.fedoraproject.org/pub/epel/7/x86_64/"
Loaded plugins: langpacks
adding repo from: http://dl.fedoraproject.org/pub/epel/7/x86_64/

[dl.fedoraproject.org_pub_epel_7_x86_64_]
name=added from: http://dl.fedoraproject.org/pub/epel/7/x86_64/
baseurl=http://dl.fedoraproject.org/pub/epel/7/x86_64/
enabled=1

A file was created in the /etc/yum.repos.d directory with the output shown. This file can now be modified to provide a customized name and the location of the GPG key. Administrators should download the key to a local file rather than allowing yum to retrieve the key from an external source.

[EPEL]
name=EPEL 7
baseurl=http://dl.fedoraproject.org/pub/epel/7/x86_64/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

RPM configuration package for the repository

Some repositories provide this configuration file and GPG public key as part of an RPM package that can be downloaded and installed using yum localinstall. One example of this is the volunteer project EPEL (Extra Packages for Enterprise Linux), which provides software not supported by Red Hat but compatible with Red Hat Enterprise Linux.

Installing the Red Hat Enterprise Linux 7 EPEL repo package:

[root@serverX ~]# rpm --import http://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-7
[root@serverX ~]# yum install http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-2.noarch.rpm

Configuration files often list multiple repository references in a single file. Each repository reference begins with a single-word name in square brackets.

[root@serverX ~]# cat /etc/yum.repos.d/epel.repo
[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
#baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

[epel-debuginfo]
name=Extra Packages for Enterprise Linux 7 - $basearch - Debug
#baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch/debug
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=1

[epel-source]
name=Extra Packages for Enterprise Linux 7 - $basearch - Source
#baseurl=http://download.fedoraproject.org/pub/epel/7/SRPMS
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-source-7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=1

The enabled=0 parameter can be included so that a repository is defined but not searched by default. Repositories can be enabled and disabled persistently with yum-config-manager or temporarily with --enablerepo=PATTERN and --disablerepo=PATTERN options on yum.