Image Mode: The Supported Way to Extend RHEL CoreOS
summary
Image mode (On-Cluster Layering) treats RHCOS as a buildable image inside the cluster, using a MachineOSConfig-driven build controller and build jobs to produce and push custom RHCOS images to a registry and roll them to nodes. It supports adding drivers, agents (example: ksh shell), and hotfixes in a declarative, upgrade-safe way while preserving immutability by using a move-and-link workaround for writable paths and clear guidance for `/var`. The process is supported, zero-maintenance at scale, and prevents unsafe rollouts when builds fail. MachineOSConfig Image mode / On-Cluster Layering
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chapters (8)
- 0:00Introduction and setup
- 1:07What is RHEL CoreOS Image
- 2:57Architecture and trade-offs
- 5:52Old vs new approach for custom tools
- 8:45How Image Mode builds images
- 11:18Solving immutability with Image Mode
- 13:03Real-world customer case
- 14:07Future of Image Mode
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