This improves performance of the text formatting and ktesting.
Because ktesting no longer buffers messages by default, one unit
test needs to ask for that explicitly.
The code as it stands now works, but it is still complicated and previous
versions had race
conditions (https://github.com/kubernetes/kubernetes/issues/108040). Now the
test works without modifying global state. The individual test cases could run
in parallel, this just isn't done because they complete quickly already (2
seconds).
The pod worker is the owner of when a container is running or not,
and the start and stop of the probes for a given pod should be
handled during the pod sync loop. This ensures that probes do not
continue running even after eviction.
Because the pod semantics allow lifecycle probes to shorten grace
period, the probe is removed after the containers in a pod are
terminated successfully. As an optimization, if the pod will have
a very short grace period (0 or 1 seconds) we stop the probes
immediately to reduce resource usage during eviction slightly.
After this change, the probe manager is only called by the pod
worker or by the reconcile loop.
Revert to previous behavior in 1.21/1.20 of setting pod phase to failed
during graceful node shutdown.
Setting pods to failed phase will ensure that external controllers that
manage pods like deployments will create new pods to replace those that
are shutdown. Many customers have taken a dependency on this behavior
and it was breaking change in 1.22, so this change reverts back to the
previous behavior.
Signed-off-by: David Porter <david@porter.me>
A number of race conditions exist when pods are terminated early in
their lifecycle because components in the kubelet need to know "no
running containers" or "containers can't be started from now on" but
were relying on outdated state.
Only the pod worker knows whether containers are being started for
a given pod, which is required to know when a pod is "terminated"
(no running containers, none coming). Move that responsibility and
podKiller function into the pod workers, and have everything that
was killing the pod go into the UpdatePod loop. Split syncPod into
three phases - setup, terminate containers, and cleanup pod - and
have transitions between those methods be visible to other
components. After this change, to kill a pod you tell the pod worker
to UpdatePod({UpdateType: SyncPodKill, Pod: pod}).
Several places in the kubelet were incorrect about whether they
were handling terminating (should stop running, might have
containers) or terminated (no running containers) pods. The pod worker
exposes methods that allow other loops to know when to set up or tear
down resources based on the state of the pod - these methods remove
the possibility of race conditions by ensuring a single component is
responsible for knowing each pod's allowed state and other components
simply delegate to checking whether they are in the window by UID.
Removing containers now no longer blocks final pod deletion in the
API server and are handled as background cleanup. Node shutdown
no longer marks pods as failed as they can be restarted in the
next step.
See https://docs.google.com/document/d/1Pic5TPntdJnYfIpBeZndDelM-AbS4FN9H2GTLFhoJ04/edit# for details
