fix: resolve kernel version detection for Debian/Ubuntu meta-packages

[RuTHlessBEat200]

Fix: Resolve kernel version detection for Debian/Ubuntu meta-packages

Problem

On Debian-based virtualized systems, the agent incorrectly reported kernel version mismatches, causing false-positive reboot requirements. The issue occurred because meta-packages like linux-image-virtual, linux-image-generic, etc., were not being resolved to their actual kernel versions.

Changes

1. Updated getLatestKernelFromBoot()

• Removed filter that excluded "generic" kernels
• Now only skips "recovery" kernels
• Properly detects kernels like 6.8.0-90-generic from /boot directory

2. Rewrote getLatestKernelFromDpkg()

• Multi-stage detection: first scans for actual kernel packages with full version numbers
• Identifies meta-packages (virtual, generic, lowlatency, server, cloud, kvm)
• Falls back to dependency resolution if only meta-packages are found
• Properly sorts all found kernels to return the latest version

3. Added resolveMetaPackage()

• New function to resolve meta-packages to actual kernel versions
• Uses dpkg-query to read package dependencies
• Parses dependency strings to find correct kernel packages
• Filters out nested meta-packages

Testing

Tested on Raspberry Pi 5 (Debian 13)

patchmon-agent diagnostics 2>&1 | grep -A 5 -i "reboot"
  time="2025-12-24T03:25:31" level=info msg="Reboot status check completed" installed_kernel=6.12.47+rpt-rpi-v8 needs_reboot=false reason= running_kernel=6.12.47+rpt-rpi-v8

Correctly detects matching kernels with custom suffixes

Tested on Proxmox VE

patchmon-agent diagnostics 2>&1 | grep -A 5 -i "reboot"
  time="2025-12-24T03:25:15" level=info msg="Reboot status check completed" installed_kernel=6.17.4-1-pve needs_reboot=true reason="Reboot flag file exists (/var/run/reboot-required) | Running kernel: 6.17.2-2-pve, Installed kernel: 6.17.4-1-pve" running_kernel=6.17.2-2-pve

Correctly detects actual kernel updates requiring reboot

Tested on Ubuntu 24.04 (Virtualized)

Before fix:

patchmon-agent diagnostics 2>&1 | grep -A 5 -i "reboot"
  time="2025-12-24T03:25:20" level=info msg="Reboot status check completed" installed_kernel=virtual needs_reboot=true reason="Kernel version mismatch | Running kernel: 6.8.0-90-generic, Installed kernel: virtual" running_kernel=6.8.0-90-generic

False positive - meta-package not resolved

After fix:

patchmon-agent diagnostics 2>&1 | grep -A 5 -i "reboot"
  time="2025-12-24T03:19:55" level=info msg="Reboot status check completed" installed_kernel=6.8.0-90-generic needs_reboot=false reason= running_kernel=6.8.0-90-generic

Correctly resolves linux-image-virtual to 6.8.0-90-generic

Impact

• Eliminates false-positive reboot requirements on virtualized Debian/Ubuntu systems
• Should maintain backward compatibility with RHEL/Fedora systems
• Should work across all Linux distributions with proper fallback mechanisms
• No breaking changes to existing functionality

Notes (important)

Testing required before merge
This fix has been tested on Debian-based systems (Debian 13, Ubuntu 24.04, Raspberry Pi OS). I only had VMs/physical devices with these distributions in my home lab. Before merging, it should be tested on all OS distributions (all those officially supported by the project).

[9technologygroup]

Hi :)

I will be spending some time testing this throughout the week.

Many thanks for the PR and the work you've put into it for sure.

Thanks
iby