Chapter 1. Introducing RHEL for Edge images
A RHEL for Edge image is an rpm-ostree
image that includes system packages to remotely install RHEL on Edge servers.
The system packages include:
-
Base OS
package - Podman as the container engine
- Additional RPM Package Manager (RPM) content
Differently from RHEL images, RHEL for Edge is an immutable operating system, that is, it contains a read-only
root directory with the following characteristics:
- The packages are isolated from the root directory.
- Each version of the operating system is a separate deployment. Therefore, you can roll back the system to a previous deployment when needed.
- Offers efficient updates over the network.
- Supports multiple operating system branches and repositories.
-
Contains a hybrid
rpm-ostree
package system
You can deploy a RHEL for Edge image on Bare Metal, Appliance, and Edge servers.
With a RHEL for Edge image, you can achieve the following benefits:
- Atomic upgrades
- You know the state of each update, and no changes are seen until you reboot your system.
- Custom health checks and intelligent rollbacks
- You can create custom health checks, and if a health check fails, the operating system rolls back to the previous stable state.
- Container-focused workflow
- The image updates are staged in the background, minimizing any workload interruptions to the system.
- Optimized Over-the-Air updates
- You can make sure that your systems are up-to-date, even with intermittent connectivity, thanks to efficient over-the-air (OTA) delta updates.
1.1. Difference between RHEL RPM images and RHEL for Edge images
You can create RHEL system images in traditional package-based RPM format and also as RHEL for Edge (rpm-ostree
) images.
You can use the traditional package-based RPMs to deploy RHEL on traditional data centers. However, with RHEL for Edge images you can deploy RHEL on servers other than traditional data centers. These servers include systems where processing of large amounts of data is done closest to the source where data is generated, the Edge servers.
The RHEL for Edge (rpm-ostree
) images are not a package manager. They only support complete bootable file system trees, not individual files. These images do not have information regarding the individual files such as how these files were generated or anything related to their origin.
The rpm-ostree
images need a separate mechanism, the package manager, to install additional applications in the /var
directory. With that, the rpm-ostree
image keeps the operating system unchanged, while maintaining the state of the /var
and /etc
directories. The atomic updates enable rollbacks and background staging of updates.
Refer to the following table to know how RHEL for Edge images differ from the package-based RHEL RPM images.
Key attributes | RHEL RPM image | RHEL for Edge image |
| You can assemble the packages locally to form an image. | The packages are assembled in an OSTree which you can install on a system. |
|
You can use |
You can use |
| The package contains DNF repositories | The package contains OSTree remote repository |
| Read write |
Read-only ( |
|
You can mount the image to any non |
|