* Kubelet GracefulNodeShutdown works, but only partially handles
gracefully stopping the Kubelet. The most noticeable drawback
is that Completed Pods are left around
* Use a project like poseidon/scuttle or a similar systemd unit
as a snippet to add drain and/or delete behaviors if desired
* This reverts commit 1786e34f33.
Rel:
* https://www.psdn.io/posts/kubelet-graceful-shutdown/
* https://github.com/poseidon/scuttle
* delete-node.service used to be used to remove nodes from the
cluster on shutdown, but its long since it last worked properly
* If there is still a desire for this concept, it can be added
with a custom snippet and with a better systemd unit
* network.target is a passive unit that's not actually pulled
in by units requiring or wanting it, its only used for shutdown
ordering
> "Services using the network should ... avoid any Wants=network.target or even Requires=network.target"
Rel: https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/
* Disable Kubelet Graceful Node Shutdown on worker nodes (enabled in
Kubernetes v1.25.0 https://github.com/poseidon/typhoon/pull/1222)
* Graceful node shutdown shutdown allows 30s for critical pods to
shutdown and 15s for regular pods to shutdown before releasing the
inhibitor lock to allow the host to shutdown
* Unfortunately, both pods and the node are shutdown at the same
time at the end of the 45s period without further configuration
options. As a result, regular pods and the node are shutdown at the
same time. In practice, enabling this feature leaves Error or Completed
pods in kube-apiserver state until manually cleaned up. This feature
is not ready for general use
* Fix issue where Error/Completed pods are accumulating whenever any
node restarts (or auto-updates), visible in kubectl get pods
* This issue wasn't apparent in initial testing and seems to only
affect non-critical pods (due to critical pods being killed earlier)
But its very apparent on our real clusters
Rel: https://github.com/kubernetes/kubernetes/issues/110755
* When podman runs the Kubelet container, logging to journald means
log lines are duplicated in the journal. journalctl -u kubelet shows
Kubelet's logs and the same log messages from podman. Using the
k8s-file driver alleviates this problem
* Fix Kubelet and etcd-member logs to be more readable and reduce
unneccessary Kubelet log volume
* Kubernetes v1.25.0 moved the LocalStorageCapacityIsolationFSQuotaMonitoring
feature from alpha to beta, but it breaks Kubelet updating ConfigMaps in
Pods, as shown by conformance tests
* Kubernetes is rolling LocalStorageCapacityIsolationFSQuotaMonitoring back
to alpha so its not enabled by default, but that will require a release
* Disable the feature gate directly as a workaround for now to make
Kubernetes v1.25.0 usable
```
FailedMount: MountVolume.SetUp failed for volume "configmap-volume" : requesting quota on existing directory /var/lib/kubelet/pods/f09fae17-ff16-4a05-aab3-7b897cb5b732/volumes/kubernetes.io~configmap/configmap-volume but different pod 673ad247-abf0-434e-99eb-1c3f57d7fdaa a4568e94-2b2d-438f-a4bd-c9edc814e478
```
Rel:
* https://github.com/kubernetes/kubernetes/pull/112076
* https://github.com/kubernetes/kubernetes/pull/107329
* Changes to worker launch configurations start an autoscaling group instance
refresh to replace instances
* Instance refresh creates surge instances, waits for a warm-up period, then
deletes old instances
* Changing worker_type, disk_*, worker_price, worker_target_groups, or Butane
worker_snippets on existing worker nodes will replace instances
* New AMIs or changing `os_stream` will be ignored, to allow Fedora CoreOS or
Flatcar Linux to keep themselves updated
* Previously, new launch configurations were made in the same way, but not
applied to instances unless manually replaced
