Updating a Container's Kernel in Warewulf
Introduction
By default, Warewulf automatically fetches the latest kernel from the assigned container image and provides that kernel during PXE booting. Using the auto-detected kernel is recommended in the vast majority of cases. In addition, performing dnf update within the container should update to the latest kernel available.
Problem
Some container images are created for specific Rocky Linux releases (e.g., Rocky Linux 8.8) and they would not have the right repositories to fetch updates, since they are built for that specific reason. Therefore the update process will not complete successfully.
Symptoms
You may see the following when running dnf update:
# dnf update
Rocky Linux 8.8 - AppStream 4.6 MB/s | 12 MB 00:02
Rocky Linux 8.8 - BaseOS 6.2 MB/s | 7.2 MB 00:01
Rocky Linux 8.8 - Extras 24 kB/s | 14 kB 00:00
Dependencies resolved.
Nothing to do.
Complete!
Resolution
There are few options available:
1 - Use a different image
Install a different image to make sure you can upgrade or downgrade to distinct versions. To change the container for your nodes without affecting operations, please follow Best Practices for Applying OS Updates Across Node Images.
2 - Use the dnf upgrade command
Use the dnf upgrade command instead and specify the release version you want to upgrade to:
$ dnf upgrade --releasever=8.10
Transaction Summary
=============================================================================================================================
Install 24 Packages
Upgrade 127 Packages
Total download size: 593 M
Is this ok [y/N]:
If you run into the following error while running the above command:
Errors during downloading metadata for repository 'appstream':
- Status code: 404 for http://dl.rockylinux.org/vault/rocky/8.10/AppStream/x86_64/os/repodata/repomd.xml (IP: 151.101.54.132)
Error: Failed to download metadata for repo 'appstream': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried
Make sure to comment out the _baseurl_ line in the /etc/yum.repos.d directory and uncomment the _mirror_ line. You can use the command below:
sed -i -E 's/^(baseurl)/#\1/; s/^#(mirror)/\1/' /etc/yum.repos.d/*
Verify changes and try again.
3 - Change the repositories within the container image
You can manually set the /etc/yum.repos.d/* repositories to your preferred URLs for the version you want to upgrade to.