* 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
* Change the workers managed instance group to health check nodes
via HTTP probe of the kube-proxy port 10256 /healthz endpoints
* Advantages: kube-proxy is a lower value target (in case there
were bugs in firewalls) that Kubelet, its more representative than
health checking Kubelet (Kubelet must run AND kube-proxy Daemonset
must be healthy), and its already used by kube-proxy liveness probes
(better discoverability via kubectl or alerts on pods crashlooping)
* Another motivator is that GKE clusters also use kube-proxy port
10256 checks to assess node health
* When a worker managed instance group's (MIG) instance template
changes (including machine type, disk size, or Butane snippets
but excluding new AMIs), use Google Cloud's rolling update features
to ensure instances match declared state
* Ignore new AMIs since Fedora CoreOS and Flatcar Linux nodes
already auto-update and reboot themselves
* Rolling updates will create surge instances, wait for health
checks, then delete old instances (0 unavilable instances)
* Instances are replaced to ensure new Ignition/Butane snippets
are respected
* Add managed instance group autohealing (i.e. health checks) to
ensure new instances' Kubelet is running
Renames
* Name apiserver and kubelet health checks consistently
* Rename MIG from `${var.name}-worker-group` to `${var.name}-worker`
Rel: https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups
* 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
* Requires poseidon v0.11+ and Flatcar Linux 3185.0.0+ (action required)
* Previously, Flatcar Linux configs have been parsed as Container
Linux Configs to Ignition v2.2.0 specs by poseidon/ct
* Flatcar Linux starting in 3185.0.0 now supports Ignition v3.x specs
(which are rendered from Butane Configs, like Fedora CoreOS)
* poseidon/ct v0.11.0 adds support for the flatcar Butane Config
variant so that Flatcar Linux can use Ignition v3.x
Rel:
* [Flatcar Support](https://flatcar-linux.org/docs/latest/provisioning/ignition/specification/#ignition-v3)
* [poseidon/ct support](https://github.com/poseidon/terraform-provider-ct/pull/131)
* Google Cloud Terraform provider resource google_dns_record_set's
name field provides the full domain name with a trailing ".". This
isn't a new behavior, Google has behaved this way as long as I can
remember
* etcd domain names are passed to the bootstrap module to generate
TLS certificates. What seems to be new(ish?) is that etcd peers
see example.foo and example.foo. as different domains during TLS
SANs validation. As a result, clusters with multiple controller
nodes fail to run etcd-member, which manifests as cluster provisioning
hanging. Single controller/master clusters (default) are unaffected
* Fix etcd-member.service error in multi-controller clusters:
```
"error":"x509: certificate is valid for conformance-etcd0.redacted.,
conform-etcd1.redacted., conform-etcd2.redacted., not conform-etcd1.redacted"}
```
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
* Add `boot_disk[0].initialize_params` to the ignored fields for the
controller nodes
* Nodes will auto-update, Terraform should not attempt to delete and
recreate nodes (especially controllers!). Lack of this ignore causes
Terraform to propose deleting controller nodes when Flatcar Linux
releases new images
* Matches the configuration on Typhoon Fedora CoreOS (which does not
have the issue)
* 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
* Use the official Kinvolk Flatcar Linux image on Google Cloud
* Change `os_image` from a custom image name to `flatcar-stable`
(default), `flatcar-beta`, or `flatcar-alpha` (**action required**)
* Change `os_image` from a required to an optional variable
* Promote Typhoon on Flatcar Linux / Google Cloud to stable
* Remove docs about needing to upload a Flatcar Linux image
manually on Google Cloud and drop support for custom images
* 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)
* Change `enable_aggregation` default from false to true
* These days, Kubernetes control plane components emit annoying
messages related to assumptions baked into the Kubernetes API
Aggregation Layer if you don't enable it. Further the conformance
tests force you to remember to enable it if you care about passing
those
* This change is motivated by eliminating annoyances, rather than
any enthusiasm for Kubernetes' aggregation features
Rel: https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/apiserver-aggregation/
* Mount both /etc/ssl/certs and /etc/pki into control plane static
pods and kube-proxy, rather than choosing one based a variable
(set based on Flatcar Linux or Fedora CoreOS)
* Remove deprecated `--port` from `kube-scheduler` static Pod
* Update `null` provider to allow use of v3.1.x releases,
instead of being stuck on v2.1.2
* Update min versions in terraform-render-boostrap
https://github.com/poseidon/terraform-render-bootstrap/pull/287
* Document the recommended versions of Terraform cloud providers
