Configuring repositories: remote, local and registered

Do these on your own system. They get harder. Check each result, then tick it off.

1. Warm-upDone

   What repositories does this system use?

   List the enabled repositories, then list all of them including disabled ones, and find the file that defines each. Count how many are enabled.

   Check your result

   dnf repolist prints repo id and name. dnf repolist all includes disabled entries. Definitions are under /etc/yum.repos.d/.

   Hint

   ls /etc/yum.repos.d and grep -H '^\[' /etc/yum.repos.d/*.repo.

   Solution

   dnf repolist
   dnf repolist all | head
   ls /etc/yum.repos.d
   grep -H '^\[' /etc/yum.repos.d/*.repo

2. PracticeDone

   Configure two remote repositories

   Your instructions say the system must use http://content.example.com/rhel10/BaseOS and http://content.example.com/rhel10/AppStream as its software sources. Create one file /etc/yum.repos.d/exam.repo with two repository sections named exam-baseos and exam-appstream, both enabled. The signing key is not available, so GPG checking is off. Confirm DNF accepts the file (the URLs may not resolve in your lab).

   Check your result

   dnf repolist lists exam-baseos and exam-appstream (or fails with a download error for the host, proving DNF read the file). grep gpgcheck /etc/yum.repos.d/exam.repo shows gpgcheck=0 twice.

   Hint

   Each section needs [id], name=, baseurl=, enabled=1, gpgcheck=0. The id goes in square brackets and must be unique.

   Solution

   sudo tee /etc/yum.repos.d/exam.repo <<'EOT'
   [exam-baseos]
   name=Exam BaseOS
   baseurl=http://content.example.com/rhel10/BaseOS
   enabled=1
   gpgcheck=0
   
   [exam-appstream]
   name=Exam AppStream
   baseurl=http://content.example.com/rhel10/AppStream
   enabled=1
   gpgcheck=0
   EOT
   dnf repolist

3. PracticeDone

   Use an ISO as a local repository, persistently

   Attach the RHEL 10 installation ISO (or any ISO with BaseOS and AppStream folders) as /dev/sr0. Mount it at /mnt/dvd read-only, make the mount survive a reboot, and write /etc/yum.repos.d/dvd.repo with two repositories pointing to file:///mnt/dvd/BaseOS and file:///mnt/dvd/AppStream. Show that you can install a package from it with all other repositories disabled.

   Check your result

   findmnt /mnt/dvd shows iso9660. mount -a produces no error. sudo dnf --disablerepo='' --enablerepo='dvd-' install -y tree succeeds.

   Hint

   /dev/sr0 /mnt/dvd iso9660 ro 0 0 in /etc/fstab. For a plain file: loop in the options. Two repo sections, each with its own baseurl.

   Solution

   sudo mkdir -p /mnt/dvd
   echo '/dev/sr0 /mnt/dvd iso9660 ro 0 0' | sudo tee -a /etc/fstab
   sudo systemctl daemon-reload
   sudo mount -a
   findmnt /mnt/dvd
   sudo tee /etc/yum.repos.d/dvd.repo <<'EOT'
   [dvd-baseos]
   name=DVD BaseOS
   baseurl=file:///mnt/dvd/BaseOS
   enabled=1
   gpgcheck=0
   
   [dvd-appstream]
   name=DVD AppStream
   baseurl=file:///mnt/dvd/AppStream
   enabled=1
   gpgcheck=0
   EOT
   sudo dnf --disablerepo='*' --enablerepo='dvd-*' install -y tree

4. PracticeDone

   Create a repository from a folder of RPMs

   Make /srv/localrepo, put the RPM for tree in it (dnf download --destdir), generate the repository metadata, add a repo definition and install tree from this repository only.

   Check your result

   /srv/localrepo/repodata/repomd.xml exists. dnf --disablerepo='*' --enablerepo=localrepo install -y tree works.

   Hint

   createrepo_c /srv/localrepo (package createrepo_c). Use baseurl=file:///srv/localrepo. Re-run createrepo_c whenever the folder changes.

   Solution

   sudo dnf install -y createrepo_c
   sudo mkdir -p /srv/localrepo
   sudo dnf download --destdir /srv/localrepo tree
   sudo createrepo_c /srv/localrepo
   sudo tee /etc/yum.repos.d/localrepo.repo <<'EOT'
   [localrepo]
   name=Local repository
   baseurl=file:///srv/localrepo
   enabled=1
   gpgcheck=0
   EOT
   sudo dnf --disablerepo='*' --enablerepo=localrepo install -y tree

5. ChallengeDone

   Repair a repository that fails

   Break localrepo in three different ways, one at a time, and read the error each time: a wrong baseurl path, a missing repodata folder, and gpgcheck=1 with no key. For each, note the error text and the fix. Finish with a clean dnf clean all and dnf repolist.

   Check your result

   The wrong path gives Cannot download repomd.xml or No such file. The missing metadata gives the same message. gpgcheck=1 gives Public key for tree-... is not installed or a GPG check failure. After fixing all, dnf repolist lists localrepo.

   Hint

   dnf clean all removes cached metadata so the next command re-reads it. Fix GPG by importing the key (rpm --import) or, for a lab repo you trust, gpgcheck=0.

   Solution

   sudo sed -i 's#file:///srv/localrepo#file:///srv/nowhere#' /etc/yum.repos.d/localrepo.repo
   sudo dnf clean all; dnf --disablerepo='*' --enablerepo=localrepo repolist
   sudo sed -i 's#nowhere#localrepo#' /etc/yum.repos.d/localrepo.repo
   sudo mv /srv/localrepo/repodata /srv/repodata.off
   sudo dnf clean all; dnf --disablerepo='*' --enablerepo=localrepo repolist
   sudo mv /srv/repodata.off /srv/localrepo/repodata
   sudo sed -i 's/gpgcheck=0/gpgcheck=1/' /etc/yum.repos.d/localrepo.repo
   sudo dnf --disablerepo='*' --enablerepo=localrepo install -y tree
   sudo sed -i 's/gpgcheck=1/gpgcheck=0/' /etc/yum.repos.d/localrepo.repo
   sudo dnf clean all; dnf repolist