The weekly rolling OS-update cycle has been silently stripping docker.io from
worker nodes (DEV-498), breaking the Forgejo runner whose hostPath mount for
/var/run/docker.sock requires the socket to exist. Fix in two layers:
- Defensive pin: update-node.sh now runs `apt-mark manual docker.io` in the
apt phase (whenever it is installed) so `apt-get autoremove --purge` cannot
silently drop it during subsequent upgrades.
- Post-reboot reconciliation: new `ensure-node-docker.sh` installs docker.io
if missing, enables + starts the systemd unit, waits for /var/run/docker.sock,
and re-applies the `basicstack.de/docker=true` label. Wired into
update-node.sh between kubelet-Ready and uncordon. No-op on nodes without
the label (safe for cp-1 and the update runner).
Verified idempotent against all 5 labeled workers; `apt-mark manual docker.io`
now set on every worker (survived across reboots by design).
Co-Authored-By: Paperclip <noreply@paperclip.ing>
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