How to convert CentOS Linux to RHEL in-place on AWS

On June 30, 2024, CentOS Linux 7 will reach End of Life (EOL). Explore Red Hat’s options to help ease your migration, including Red Hat Enterprise Linux 7 for Third Party Linux Migration. Find out more

Red Hat Enterprise Linux (RHEL) provides convert2rhel, a utility that enables a guided and supported conversion of select RHEL-derived operating systems such as CentOS Linux and Oracle Linux to fully supported RHEL systems in three basic steps:

1. Configures access to authentic RHEL content in your instance
2. Performs various safety checks and reviews informational and remediation guidance on how to proceed
3. Performs the conversion by replacing every operating system package with the RHEL equivalent. There is no application or data to migrate—CentOS Linux bits are simply replaced by the RHEL equivalents. This is somewhat equivalent to a minor release update in which most or all of the packages are updated, and takes the same amount of time.

For a demonstration of how RHEL’s convert2rhel tool makes this an easy process, watch the following video or try our self-paced labs tutorial to become familiar with the process.

This blog post explains how the convert2rhel tool simplifies two commonly requested paths for converting CentOS Linux instances running on Amazon Web Services (AWS) to fully supported RHEL, including: 

1. Converting a CentOS Linux instance in-place to RHEL with Bring Your Own Subscription (BYOS)
2. Converting a CentOS Linux instance in-place to RHEL with Pay As You Go (PAYG) using the BYOS model

“Wait, why would I want to convert to RHEL?”

We are very glad you asked!  The obvious benefits include the ability to open a support case and access to the thousands of knowledgebase articles at the Red Hat Customer Portal.  However, the RHEL product and subscription provides much more that is not obvious to many users, including content and capabilities that simply do not exist with non-RHEL options.

RHEL provides a flexible and stable foundation to support hybrid cloud innovation. Deploy applications and critical workloads faster with a consistent experience across physical, virtual, private and public cloud, and edge deployments.

Security and compliance

RHEL has an industry-leading reputation for security and compliance, providing a software supply chain with a stronger security footprint, tools to apply and audit, as well as certifications to better meet industry and government security requirements.

Red Hat Enterprise Linux life cycle

The RHEL life cycle provides:

• A well defined and predictable cadence for life cycle planning for our customers, partners, ISVs and the RHEL ecosystem
• The ability to request feature enhancements and maintenance fixes according to well-defined life cycle phases
• Options for Extended Update Support (EUS) providing two year streams of security and bug fixes for select minor releases 
• The option for Extended Life Cycle Support (ELS) providing a bridge of critical security fixes to assist you in upgrading from end of maintenance releases
• Major release upgrade paths to RHEL 7, 8, 9 and later are fully tested and supported

Red Hat Insights

Red Hat Insights is a managed service that continuously analyzes platforms and applications to predict risk, recommend actions and analyze costs to help you better manage IT spending and your hybrid cloud environments. Included with all RHEL subscriptions, Insights gathers configuration and utilization data, then analyzes and provides insights from that data to proactively identify and fix issues. It delivers continuous vulnerability alerts and targeted guidance to help you maximize uptime and avoid emergencies due to security issues, non-compliant settings, unpatched systems and configuration drift. Insights is included with every RHEL subscription.

Red Hat Hybrid Cloud Console is a feature-rich management experience within Insights and is also included with every RHEL subscription.

In addition to purchasing a subscription for access to all that RHEL has to offer, Red Hat provides multiple ways to learn about and access RHEL for development use cases.

For an individual developer, learner and casual user, Red Hat offers a developer subscription for individuals for use on personal servers, home labs and in small open source communities. 

For the business and enterprise, Red Hat provides the leading experience for a secure and manageable platform for applications. For development teams within organizations already using other Red Hat technologies, we offer a Red Hat Developer Subscription for Teams that provides a no-cost subscription with all of the same features to help you to become an expert.

“That sounds great!  So, how do I convert my CentOS Linux to RHEL?”

The first thing to consider is how you intend to pay for your RHEL subscription.  You have a few different options.

Bring Your Own Subscription (BYOS)

The first option is an annual subscription for RHEL which you obtain directly from Red Hat or a reseller. If you choose to replace your CentOS Linux with an annual subscription of RHEL, review the following options depending on how you obtain your subscription.

“My company already has RHEL subscriptions.”

Great!  Follow these steps to create an activation key and begin.

1. Login to the Red Hat Hybrid Cloud Console and view your subscriptions.

2. For the best experience, ensure that Simple Content Access (SCA) is enabled.  Otherwise, you will need to manually specify which subscription to use when you register the instance you wish to convert.
3. If using SCA, click on menu item All Apps & Services > Remote Host Configuration > Activation Keys.  This will allow you to create a named Activation Key, such as “my_conversions”, to provide to the convert2rhel utility in a later step.  If you choose not to use SCA and Activation keys, you will need to follow the instructions for registering with the subscription manager tool using a username and password, and attaching a specific subscription.  SCA + Activation Keys are far easier and are the recommended method.

“What if I do not already have a subscription?”

No problem! We have a few options for you.

Option 1 - purchase a RHEL subscription 

You can purchase a RHEL subscription by speaking with your Red Hat sales representative or Red Hat partner if you have one, or by simply clicking the blue "Purchase subscriptions" button as shown in the image above.

Option 2 - request a 60 day self-supported RHEL evaluation subscription 

This 60-day trial subscription provides a single evaluation subscription to help you get started with a single instance. This is a great way to evaluate this experience on a test system. Please note that evaluation trial subscriptions are not recommended for production or longer term solutions. After 60 days it will expire at which time the instance would no longer be able to receive updates such as security and bug fixes. This will require obtaining some other subscription in the future. 

Option 3 - request a Developer subscription for individuals

The developer subscription for individuals is a great option for an individual developer, learner, and casual user.  It provides 16 subscriptions that can be used for personal servers, home labs and in small open source communities.

“Okay, that is done.  Can I convert now?”

Yes, you are now ready to register a system and begin the conversion process!  Use the Organization ID (found on the  Activation Keys page) and the activation key that you created in the previous steps. This enables the convert2RHEL utility to register the system and perform the conversion.

1. Red Hat cares about your data and systems.  Red Hat strongly recommends creating backups of your volume in the event of unexpected problems.  Within AWS, you can do this by taking a snapshot of the associated Elastic BlockStorage (EBS) volume. More information can be found at in the AWS User Guide 
2. Review the documentation for Converting from an RPM-based Linux distribution to RHEL.  Please review this carefully so that you understand the support matrix, preparations, and other important details.
3. A reminder that backups are strongly encouraged!
4. Login to the instance using SSH or the AWS terminal to access a shell prompt.  This will allow you to execute the following commands.  The user account will require permissions to use the sudo command or become the root super user.
5. Update to the latest supported version and install errata updates. Reboot the instance to ensure the latest updates and kernel are applied.

# sudo yum -y update

6. Install a few prerequisites and initiate the conversion.

Copy files to validate that the content is signed by Red Hat. 

# sudo curl -o /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release https://www.redhat.com/security/data/fd431d51.txt
# sudo curl --create-dirs -o /etc/rhsm/ca/redhat-uep.pem https://ftp.redhat.com/redhat/convert2rhel/redhat-uep.pem

For CentOS 7

# sudo curl -o /etc/yum.repos.d/convert2rhel.repo https://ftp.redhat.com/redhat/convert2rhel/7/convert2rhel.repo

For CentOS 8

# sudo curl -o /etc/yum.repos.d/convert2rhel.repo https://ftp.redhat.com/redhat/convert2rhel/8/convert2rhel.repo
# sudo yum -y install convert2rhel

7. Create a configuration file containing the activation key and save the file in the .ini file format.  This is the recommended method for activation keys and passwords to ensure that sensitive information is not leaked.  You can delete the file when the process is complete.  In this example, the vi text editor is used but you can use your editor of choice.

# sudo vi /etc/convert2rhel.ini

[subscription_manager]
activation_key = <activation_key>

8. Initiate the conversion tool

# sudo convert2rhel --org <Organization_ID> --config-file <config_file_name>

9. After conversion, it is highly recommended to register with the insights-client to enable your additional management capabilities at the Red Hat Hybrid Cloud Console.

# sudo insights-client --register

10. After following any remaining guidance in the documentation, the system will be ready to be restarted as 100% authentic RHEL.  If you registered with Insights, you will now see your system in the Inventory.
11. And you’re done!

Pay As You Go (PAYG)

PAYG, sometimes referred to as on-demand billing, is commonly used in public clouds to allow for metered usage billing of cloud instances, typically by the hour or day.  PAYG allows for a single payment transaction to the cloud provider to pay for both the instance compute and third party software licenses or subscriptions.

With this scenario, a specific annual subscription associated with a specific cloud instance may not be the best option. For example, ephemeral workloads which dynamically launch short-lived virtual machine instances and then destroy them after the task finishes, make it challenging to manage the subscriptions that they consume. 

This requires consideration for how to enable the conversion process to RHEL.  Because cloud partners typically enable PAYG metered billing using codes embedded at a very low level of the cloud instance, it is not possible to change these billing codes today in order to enable metered billing of the RHEL instances after conversion.  Therefore, if you want to pay for RHEL in a metered way, such as hourly consumption, you will need to instead use the RHEL images prebuilt and published in the AWS Console or Marketplace.

You may, however, proceed to convert instances to RHEL using the same process as the BYOS method outlined above.  If you choose to do this, we have some tooling to improve the experience and make it easy for you to manage your subscriptions.

Cloud-Based Auto-Registration

By enabling Auto-Registration, Simple Content Access (SCA), and Subscription Watch, you will enable fleet-level registration for Red Hat workloads running in select public cloud environments to auto-connect and gain full access to Red Hat content, analytics and tools to manage your fleet across multiple hybrid cloud environments.  No matter how you choose to pay for Red Hat subscriptions, BYOS or PAYG, you will have the best and most comprehensive experience possible.

• Step 1:  Follow the simple instructions to configure the mapping of Sources between your Red Hat and Cloud Partner accounts in Cloud Based Auto-Registration.
• Step 2: Enable Subscription Watch (optional but recommended).
• Step 3: Follow the same instructions defined in the BYOS section above to convert in-place to RHEL.

Want to learn more?

More about conversions and migrations to RHEL

• Converting from an RPM-based Linux distribution to RHEL 
• Convert2RHEL Support Policy
• Convert2RHEL FAQ (Frequently Asked Questions) 
• Top 10 considerations for moving from CentOS Linux to RHEL
• Convert from CentOS Linux to Red Hat Enterprise Linux
• Self-Paced Labs: Migrating from CentOS Linux to Red Hat Enterprise Linux  
• Convert from CentOS Linux with Convert2RHEL

More about Red Hat subscriptions

1. Hybrid cloud your way: Automating the RHEL registration process 
2. Cloud Based Auto-Registration.
3. Transition of Red Hat's subscription services to console.redhat.com 
4. Simple Content Access - Red Hat Customer Portal 

We’re here to help

As convert2rhel has been enhanced over the past several years, Red Hat Consulting Services  has been instrumental in assisting many customers with very large enterprise conversions.  If the thought of converting a large environment has you feeling overwhelmed or not sure where to begin, Red Hat Consulting Services can share their expertise and guidance to help you get there, and possibly save you time and money in the process.