Procedure

1. Back up your system and verify that you can restore your system.
2. Check Known issues and limitations and verify that your system is supported for conversion. Apply workarounds where applicable.

3. Ensure that the standard kernel is the booted kernel:

   • CentOS Linux: the standard CentOS Linux kernel

   • Oracle Linux: the Red Hat Compatible Kernel (RHCK)

     If the kernel your system is booted into is not the standard kernel, for example CentOS realtime kernel or Oracle Linux Unbreakable Enterprise Kernel (UEK), change the default kernel to the standard kernel and reboot your system.

4. If converting from CentOS Linux 8, remove any CentOS Stream packages from your system. CentOS Stream is not currently supported for conversion, and the conversion might fail if any packages are present on the system.

5. If you are converting with a firewall, using Red Hat Satellite, or through a proxy server, ensure that you have access to the following connections:

   • https://ftp.redhat.com
   • https://cdn-ubi.redhat.com
   • https://cdn.redhat.com
   • https://subscription.rhsm.redhat.com - required only for systems with firewalls
   • https://*.akamaiedge.net - required only for systems with firewalls
   • https://static.redhat.com

6. If converting from CentOS Linux 8, update the CentOS repository URLs:

   # sed -i 's/^mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
   # sed -i 's|#baseurl=http://mirror.centos.org|baseurl=https://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

   Important

   CentOS Linux 8 has reached end of life. For more information, see CentOS Linux EOL.

7. Install Convert2RHEL:

   1. Download the Red Hat GPG key:

      # curl -o /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release https://www.redhat.com/security/data/fd431d51.txt

   2. Download the SSL certificate of the https://cdn.redhat.com server, which contains the Convert2RHEL repositories:

      # curl --create-dirs -o /etc/rhsm/ca/redhat-uep.pem https://ftp.redhat.com/redhat/convert2rhel/redhat-uep.pem

   3. Install the Convert2RHEL repository file:

      # curl -o /etc/yum.repos.d/convert2rhel.repo https://ftp.redhat.com/redhat/convert2rhel/<version_number>/convert2rhel.repo

      Replace version_number with the appropriate major version of the OS, for example 7 or 8.

      Note

      You must perform the conversion with the latest version of the Convert2RHEL repository file. If you had previously installed an earlier version of the repository file, remove the earlier version and install the current version.

   4. Install the Convert2RHEL utility:

      # yum -y install convert2rhel

8. Ensure you have access to RHEL packages through one of the following methods:

   1. Red Hat Content Delivery Network (CDN) through Red Hat Subscription Manager (RHSM). You must have a Red Hat account and an appropriate RHEL subscription to access RHSM. Note that the OS will be converted to the corresponding minor version of RHEL per Table 1.1.

   2. Red Hat Satellite in a version that has Full or Maintenance support. For more information, see Red Hat Satellite Product Life Cycle.

      Note

      Ensure that the Satellite server meets the following conditions:

      • Satellite has a subscription manifest with RHEL repositories imported. For more information, see the Managing Subscriptions chapter in the Content Management Guide for the particular version of Red Hat Satellite, for example, for version 6.10.

      • All required repositories are enabled and synchronized with the latest target OS updates and published on Satellite. Enable at minimum the following repositories for the appropriate major version of the OS:

        • Red Hat Enterprise Linux 7 Server RPMs x86_64 7Server
        • Red Hat Enterprise Linux 8 for x86_64 - AppStream RPMs <target_os>
        • Red Hat Enterprise Linux 8 for x86_64 - BaseOS RPMs <target_os>

      Replace target_os with 8.4 or 8.5 for CentOS Linux conversions and 8.7 for Oracle Linux conversions.

   3. Custom repositories configured in the /etc/yum.repos.d/ directory and pointing to a mirror of the target OS repositories. Use custom repositories for systems that have access to only local networks or portable media and therefore cannot access Red Hat CDN through RHSM. Make sure that the repositories contain the latest content available for that RHEL minor version to prevent downgrading and potential conversion failures. For more information, see Creating a Local Repository and Sharing With Disconnected/Offline/Air-gapped Systems.

      Note

      RHEL 8 content is distributed through two default repositories, BaseOS and AppStream. If you are accessing RHEL packages through custom repositories, you must configure both default repositories for a successful conversion. When running the Convert2RHEL utility, make sure to enable both repositories using the --enablerepo option. For more information about RHEL 8 repositories, see Considerations in adopting RHEL 8.

9. If you are accessing RHEL packages through a Red Hat Satellite server, download the consumer RPM to the /usr/share/convert2rhel/subscription-manager/ directory:

   # curl --insecure --output /usr/share/convert2rhel/subscription-manager/katello-ca-consumer-latest.noarch.rpm https://<satellite.example.com>/pub/katello-ca-consumer-latest.noarch.rpm

   Replace satellite.example.com with the hostname of your Satellite server.

10. Temporarily disable antivirus software to prevent the conversion from failing.

11. Update the original OS to the minor version supported for conversion as specified in Table 1.1 and then reboot the system.

    You must perform the conversion with the latest packages from the minor version of the OS that is supported for conversion to use the rollback feature in case the conversion fails. For more information, see Conversion rollback.

Procedure

1. Start the Convert2RHEL utility.

   You can use Convert2RHEL with either RHSM or custom repositories. To display all available options, use the -h, --help option:

   # convert2rhel -h

   • To convert using RHSM with the organization ID and activation key, complete the following steps. You must use this method if you are accessing RHEL packages using Satellite:

     • Add your activation key to the /etc/convert2rhel.ini file:

       [subscription_manager]
       activation_key = <activation_key>

       Replace activation_key with the activation key from the Red Hat Customer Portal if you are using Red Hat CDN or the Satellite web UI if you are using Red Hat Satellite.

     • Start the Convert2RHEL utility:

       # convert2rhel --org <organization_ID>

       Replace organization_ID with the organization ID from the Red Hat Customer Portal if you are using Red Hat CDN or the Satellite web UI if you are using Red Hat Satellite.

       Note

       If you are accessing RHEL packages using Satellite and your system does not have internet access, add the --keep-rhsm option. Note that you must have the subscription-manager and katello-ca-consumer packages already installed and must provide both your organization ID and the configuration file containing the activation key when running the convert2rhel command.

   • To convert using RHSM with the username, password, and pool ID, complete the following steps:

     • Add your Red Hat Account password to the /etc/convert2rhel.ini file:

       [subscription_manager]
       password = <password>

       Replace password with your Red Hat Account password credentials.

     • Start the Convert2RHEL utility:

       # convert2rhel --username <username> --pool <pool_ID>

       Replace username with your Red Hat Account username credentials. Replace pool_ID with the pool ID of the subscription that you want to attach to the system. If you do not know the pool ID, omit the --pool option to generate a list of all subscriptions available for the account.

   • To convert using custom repositories, start the Convert2RHEL utility:

     # convert2rhel --no-rhsm --enablerepo <RHEL_RepoID1> --enablerepo <RHEL_RepoID2>

     Replace RHEL_RepoID with your custom repository configured in the /etc/yum.repos.d/ directory, for example, rhel-7-server-rpms or rhel-8-baseos and rhel-8-appstream.

     Note

     When converting using RHSM or custom repositories, you can enable the RHEL 7 Extras or Optional repositories manually by using the --enablerepo option to replace additional packages with their RHEL counterparts. Note that packages in the Optional repository are unsupported. For more information, see Support policy of the optional and supplementary channels in Red Hat Enterprise Linux.

2. Before Convert2RHEL starts replacing packages from the original distribution with RHEL packages, the following warning message is displayed:

   The tool allows rollback of any action until this point.
   By continuing, all further changes on the system will need to be reverted manually by the user, if necessary.

   Changes made by Convert2RHEL up to this point can be automatically reverted. Confirm that you wish to proceed with the conversion process.

3. Wait until Convert2RHEL installs the RHEL packages and finishes successfully.
4. Recommended: If you used custom repositories for the conversion, register and subscribe your RHEL system. For more information, see How to register and subscribe a system offline to the Red Hat Customer Portal?.

5. At this point, the system still runs with the original distribution kernel loaded in RAM. Reboot the system to boot the newly installed RHEL kernel.

   # reboot

6. Remove third-party packages from the original OS that remained unchanged (typically packages that do not have a RHEL counterpart). To get a list of these packages, use:

   # yum list extras --disablerepo="*" --enablerepo=<RHEL_RepoID>

   Replace RHEL_RepoID with your repository.

7. Optional: If you converted to RHEL 8.4 or RHEL 8.5, update your system to the latest minor version:

   # yum update -y

8. Optional: Perform an in-place upgrade to RHEL 9 to ensure your system is updated with the latest enhancements, security features, and bug fixes. For more information, see the Upgrading from RHEL 7 to RHEL 8 and Upgrading from RHEL 8 to RHEL 9 guides. Note that if you have converted to RHEL 7, you must first perform the in-place upgrade from RHEL 7 to RHEL 8, and then from RHEL 8 to RHEL 9.