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Step-by-Step Guide to Patching Red Hat Systems in Air-Gapped Environments

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If you work on the air gapped systems like I do, here are the steps to follow to download, transfer the updates to the air gapped systems and update.

On the Red Hat system with internet access

Set up a Red Hat Satellite server or use Red Hat CDN to download the necessary updates and create a local repository.

To download necessary updates and create a local repository, you can use the ‘reposync‘ and ‘createrepo‘ utilities. Here are the steps you can follow:
Install the ‘yum-utils‘ package which provides the ‘reposync’ utility

sudo yum install yum-utils

Create a directory where you want to store the repository files.

sudo mkdir -p /opt/local-repo

Use the reposync command to download the necessary updates and store them in the directory you created in step 2.

sudo reposync --gpgcheck -r <repository-id> -p /opt/local-repo/
or
reposync --repoid=rhel-8-for-x86_64-baseos-rpms --download-path=/opt/local-repo/

Replace with the ID of the repository you want to download updates for, such as rhel-8-for-x86_64-baseos-rpms or rhel-8-for-x86_64-appstream-rpms.This command downloads the updates for the Red Hat 8 BaseOS repository and stores them in the /opt/local-repo/ directory. You can repeat this step for other repositories as needed.

Use the createrepo command to create a repository metadata in the directory where you stored the updates.

sudo createrepo /opt/local-repo/

Set the correct ownership and permissions on the repository files using the following commands:

sudo chown -R root:root /opt/local-repo
sudo chmod -R 755 /opt/local-repo

If you plan to export the repository to a portable media, create a tarball of the repository files using the following command:

sudo tar -czvf /opt/local-repo.tar.gz /opt/local-repo/

This command creates a compressed tarball of the repository files in the /opt/ directory.

Once the updates are downloaded, created a tarball of the repository, export to a portable media such as USB drive or DVD.

On the air-gapped Red Hat System:

Insert the portable media and copy the repository to a local directory.

cp -r /media/usb/repo /opt/local-repo/

Replace /media/usb/repo with the path to the directory containing the repository on the portable media, and /opt/local-repo/ with the directory where you want to store the repository on the air-gapped system.

Create a new repository file in the /etc/yum.repos.d/ directory using your preferred text editor.

sudo vi /etc/yum.repos.d/local. Repo

Add the following lines to the file:

[local]
name=Local Repository
baseurl=file:///opt/local-repo
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

Note that baseurl should point to the directory where you copied the repository in step 1.

Save and close the repository file.

Import the Red Hat GPG key using the following command:

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

Verify that the repository is accessbible by running the following command:

yum check-update

If the command returns a list of available updates, you can install the using the following command:

yum update

If you wan tot install a specific package, you can use the following command:

yum install <package-name>

That’s it! You’ve successfully patched an air-gapped Red Hat 8 system.

Sync only the recent updates

To sync only the recent updates for a Red Hat repository, you can use the reposync utility with the –newest-only option. This option downloads only the most recent version of each package in the repository, rather than downloading all available versions.

sudo reposync --gpgcheck -r <repository-id> -p /opt/local-repo/ --newest-only

Replace <repository-id> with the ID of the repository you want to sync. You can repeat this command for multiple repositories to download only the most recent updates for all of them.

After the updates have been downloaded, you can create a local repository using the createrepo command, as described in my previous response.

By using the –newest-only option, you can reduce the amount of data that needs to be downloaded and save time and bandwidth when syncing repositories in air-gapped environments.

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