T7453: Enhance raw/qcow2 image creation #972
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Gabin-CC
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dmbaturin
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Jun 5, 2025
Description This pull request introduces improvements to the raw_image.py script responsible for building raw disk images in the VyOS build process. Main Changes Added use of kpartx to reliably map EFI and root partitions from the loop device. Introduced disk_details as an attribute on the BuildContext object to pass partition metadata through the image build steps. Improved the __exit__ method for BuildContext to unmount all mount points and clean up kpartx mappings and loop devices, even in failure cases. Fixed a crash in mount_image() when con.disk_details was not set. Added useful debug logs for loop device usage and partition mapping. Motivation The previous implementation assumed partitions like /dev/loopXp3 would appear automatically, which is unreliable across some environments (especially containers or newer systems). This PR makes the process more reliable by explicitly mapping partitions with kpartx, a tool designed for this purpose. It also ensures proper resource cleanup by unmounting and detaching everything cleanly, preventing leaked loop devices or stale mount points. Test Instructions Flavor : cloud-init.toml packages = [ "cloud-init", "qemu-guest-agent" ] image_format = ["qcow2"] disk_size = 10 [boot_settings] console_type = "ttyS0" Run: sudo ./build-vyos-image --architecture amd64 \ --build-by "[email protected]" \ --reuse-iso vyos-1.5-rolling-*.iso \ cloud-init Expected behavior: The build completes without errors. The .qcow2 image file is generated and bootable (e.g., in KVM or Proxmox). Partitions are mounted correctly via /dev/mapper/loopXp*. Signed-off-by: Gabin-CC <[email protected]>
Enhanced the raw image creation logic to dynamically detect and assign EFI and root partitions based on the number of partitions created by kpartx. - Supports both 2-partition and 3-partition layouts - Adds debug output for mapped partitions - Avoids hardcoded assumptions about partition order - Improves resilience in cloud-init and containerized build contexts Fixes build failure when /dev/loopXp3 is missing or not mapped properly. Signed-off-by: Gabin-CC <[email protected]>
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Change summary
This pull request improves the reliability and robustness of the raw image generation process in raw_image.py, specifically addressing partition mapping and environment cleanup.
Types of changes
Description
Added support for kpartx to explicitly map partitions (EFI, root) from loop devices instead of relying on /dev/loopXp*, which can be unreliable.
Introduced disk_details as an attribute of BuildContext to persist partition info throughout the image creation process.
Enhanced BuildContext.exit() to unmount all mount points, remove kpartx mappings, and detach the loop device even in failure scenarios.
Fixed a potential crash when con.disk_details was missing in mount_image().
Added debug output for better observability (e.g., loop device in use, partitions mapped).
These changes improve compatibility across a variety of environments (containers, hosts with strict udev policies) and ensure a cleaner teardown process during builds.
How Has This Been Tested?
Flavor file: cloud-init.toml
packages = [
"cloud-init",
"qemu-guest-agent"
]
image_format = ["qcow2"]
disk_size = 10
[boot_settings]
console_type = "ttyS0"
Command:
sudo ./build-vyos-image --architecture amd64 --build-by "[email protected]" --reuse-iso vyos-1.5-rolling-*.iso cloud-init
Result:
Related Task(s)
T7453
Related PR(s)
Checklist: