* 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
* Typhoon Fedora CoreOS is already using iptables nf_tables since
F36. The file to pin to legacy iptables was renamed to
/etc/coreos/iptables-legacy.stamp
fixes#1123
Enables the use of CSI drivers with a StorageClass that lacks an explicit context mount option. In cases where the kubelet lacks mounts for `/etc/selinux` and `/sys/fs/selinux`, it is unable to set the `:Z` option for the CRI volume definition automatically. See [KEP 1710](https://github.com/kubernetes/enhancements/blob/master/keps/sig-storage/1710-selinux-relabeling/README.md#volume-mounting) for more information on how SELinux is passed to the CRI by Kubelet.
Prior to this change, a not-explicitly-labelled mount would have an `unlabeled_t` SELinux type on the host. Following this change, the Kubelet and CRI work together to dynamically relabel mounts that lack an explicit context specification every time it is rebound to a pod with SELinux type `container_file_t` and appropriate context labels to match the specifics for the pod it is bound to. This enables applications running in containers to consume dynamically provisioned storage on SELinux enforcing systems without explicitly setting the context on the StorageClass or PersistentVolume.
* Fixes warning about use of deprecated field `key_algorithm` in
the `hashicorp/tls` provider. The key algorithm can now be inferred
directly from the private key so resources don't have to output
and pass around the algorithm
* Kubelet node's System UUID can be detected from the sysfs
filesystem without a host mount, but if you need to distinguish
between the host's machine-id and SystemUUID
* On cloud platforms, MachineID and SystemUUID are identical,
but on bare-metal the two differ
* Cilium (v1.8) was added to Typhoon in v1.18.5 in June 2020
and its become more impressive since then. Its currently the
leading CNI provider choice.
* Calico has grown complex, has lots of CRDs, masks its
management complexity with an operator (which we won't use),
doesn't provide multi-arch images, and hasn't been compatible
with Kubernetes v1.23 (with ipvs) for several releases.
* Both have CNCF conformance quirks (flannel used for conformance),
but that's not the main factor in choosing the default
* Kubelet now uses `containerd` as the container runtime, but
`docker.service` still starts when `docker.sock` is probed bc
the service is socket activated. Prevent this by masking the
`docker.service` unit
* Migrate from `docker-shim` to `containerd` in preparation
for Kubernetes v1.24.0 dropping `docker-shim` support
* Much consideration was given to the container runtime
choice. https://github.com/poseidon/typhoon/issues/899
provides relevant rationales
* Terraform v1.1 changed the behavior of provisioners and
`remote-exec` in a way that breaks support for expansions
in commands (including file provisioner, where `destination`
is part of an `scp` command)
* Terraform will likely revert the change eventually, but I
suspect it will take a while
* Instead, we can stop relying on Terraform's expansion
behavior. `/home/core` is a suitable choice for `$HOME` on
both Flatcar Linux and Fedora CoreOS (harldink `/var/home/core`)
Rel: https://github.com/hashicorp/terraform/issues/30243
* Both Flatcar Linux and Fedora CoreOS use systemd-resolved,
but they setup /etc/resolv.conf symlinks differently
* Prefer using /run/systemd/resolve/resolv.conf directly, which
also updates to reflect runtime changes (e.g. resolvectl)
