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fix: strip deprecated --containerd kubelet flag before kubelet starts - #137
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kubelet's own systemd unit is restarted by snapd as part of a snap
refresh, independent of and not gated by k8sd's daemon startup. The
existing in-daemon cleanup (postRefreshHook -> removeDeprecatedKubeletFlags)
only runs once k8sd itself is up, which is too late: kubelet can already
be started (and crash) with the deprecated --containerd flag, removed in
Kubernetes 1.37, before k8sd gets a chance to strip it.
Extract the cleanup into a standalone snaputil.RemoveDeprecatedKubeletFlags
function and expose it as a new hidden CLI subcommand
("k8s x-cleanup deprecated-kubelet-flags"), so a snap hook can invoke it
synchronously before kubelet is (re)started, closing the race. The
existing in-daemon call now reuses the same function, removing the
duplicate implementation.
This was referenced Oct 7, 2026
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Stacked on #132. kubelet's own systemd unit is restarted by snapd as part of a
snap refresh, independent of and not gated by k8sd's daemon startup. The existing in-daemon cleanup (postRefreshHook→removeDeprecatedKubeletFlags) only runs once k8sd itself is up, which is too late: kubelet can already be started (and crash withunknown flag: --containerd) before k8sd gets a chance to strip the deprecated flag, removed in Kubernetes 1.37. Reproduced deterministically intest_version_upgrades(kubelet: 1 restart, failingcheck_service_restarts); confirmed unrelated to #132 — different hook, different subsystem (refresh vs. bootstrap).Change
snaputil.RemoveDeprecatedKubeletFlags, safe to call before k8sd itself is up (filesystem + service restart only, no API/DB dependency).k8s x-cleanup deprecated-kubelet-flags, so a snap hook can invoke it synchronously before kubelet is (re)started, closing the race at its source.