Fix kernel panic after unattended kernel upgrade#3
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The update-initramfs diversion (to /bin/true) was permanent — applied in bootcmd with no restore. When unattended-upgrades installed a new kernel, its postinst called update-initramfs which silently did nothing. GRUB picked up the new vmlinuz but with no initrd line. On next boot the kernel couldn't load virtio_blk (module in initramfs), so the root disk was invisible and it panicked with "VFS: Unable to mount root fs". Fix: divert only during first-boot provisioning (guarded by boot-finished), then restore in runcmd so future kernel upgrades generate a working initramfs. Add e2e test that installs a second kernel flavor, verifies the initrd is created, reboots, and confirms the VM comes back on the new kernel. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@ddellacosta I finally had a little time to dig into the kernel panic we both saw. The call was coming from inside the house (overzealous "speed" hack!) |
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@ddellacosta You will probably want to undivert/unsymlink (per the "Undo" bit) your current VM and re-run update-initramfs so you don't lose your work again. |
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Gotcha, will give it a shot! |
The cloud kernel package name includes the arch suffix (linux-image-cloud-arm64 vs linux-image-cloud-amd64). Use dpkg --print-architecture inside the guest to pick the right one. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Set MODULES=dep in initramfs-tools so only modules for detected hardware (virtio) are included, instead of hundreds of bare-metal drivers. Also bump the kernel install test timeout from 300s to 600s as a safety margin under TCG emulation. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The kernel reboot test hardcoded a partition UUID specific to the current Debian cloud image. Query it from the running VM via grub-probe so the test survives base image updates. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The previous /v2/* wildcard allowed pulling any Docker image — too broad for a security-focused sandbox. Scope to library/hello-world (used by the e2e test) and add the bare /v2/ endpoint required for registry version checks. Also add CloudFront CDN (some Docker blob redirects land there instead of R2) and the uv installer redirect path on releases.astral.sh. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The official install script runs `claude install` after downloading the binary, which maps ~70 GB of virtual memory and gets OOM-killed in 512 MB VMs. Download the binary directly via curl and create the symlink ourselves, bypassing the problematic subcommand. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Verify that both tools are installed and on PATH after cloud-init provisioning. Also update CLAUDE.md to note that tests run inside this VM. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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The update-initramfs symlink (to /bin/true) made the machine unbootable after updating the kernel (no real surprise there.)
Claude explanation:
When unattended-upgrades installed a new kernel, its postinst called update-initramfs which silently did nothing. GRUB picked up the new vmlinuz but with no initrd line. On next boot the kernel couldn't load virtio_blk (module in initramfs), so the root disk was invisible and it panicked with "VFS: Unable to mount root fs".
Fix: divert only during first-boot provisioning (guarded by boot-finished), then restore in runcmd so future kernel upgrades generate a working initramfs.
Add e2e test that installs a second kernel flavor, verifies the initrd is created, reboots, and confirms the VM comes back on the new kernel.