* 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
* Rename launch configuration to use a name_prefix named after the
cluster and worker to improve identifiability
* Shorten AWS autoscaling group name to not include the launch config
id. Years ago this used to be needed to update the ASG but the AWS
provider detects changes to the launch configuration just fine
* 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)
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
* Add `arch` variable to Flatcar Linux AWS `kubernetes` and
`workers` modules. Accept `amd64` (default) or `arm64` to support
native arm64/aarch64 clusters or mixed/hybrid clusters with arm64
workers
* Requires `flannel` or `cilium` CNI
Similar to https://github.com/poseidon/typhoon/pull/875
* 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
* Since v1.21.3 switched controllers default disk type from
`gp2` to `gp3`, an iops diff has been shown (harmless, but
annoying)
* Controller nodes default to a 30GB `gp3` disk. `gp3` disks
do respect `iops` and the corresponding default is 3000
* Fix worker nodes to use official Fedora CoreOS AMIs,
instead of the older Poseidon built AMIs (now removed).
This should have been part of #1038, but was missed in
code review
* Poseidon build AMIs have been deleted (so I don't have
to keep paying to host them for people)
* Remove `/sys/fs/cgroup/systemd` mount since Flatcar Linux
uses cgroups v2
* Flatcar Linux's `docker` switched from the `cgroupfs` to
`systemd` driver without notice
* Kubernetes v1.22.0 disabled kube-controller-manager insecure
port, which was used internally for Prometheus metrics scraping
* Configure Prometheus to discover and scrape endpoints for
kube-scheduler and kube-controller-manager via the authenticated
https ports, via bearer token
* Change firewall ports to allow Prometheus (on worker nodes)
to scrape kube-scheduler and kube-controller-manager targets
that run on controller(s) with hostNetwork
* Disable the insecure port on kube-scheduler
* On Fedora CoreOS, Cilium cross-node service IP load balancing
stopped working for a time (first observable as CoreDNS pods
located on worker nodes not being able to reach the kubernetes
API service 10.3.0.1). This turned out to have two parts:
* Fedora CoreOS switched to cgroups v2 by default. In our early
testing with cgroups v2, Calico (default) was used. With the
cgroups v2 change, SELinux policy denied some eBPF operations.
Since fixed in all Fedora CoreOS channels
* Cilium requires new mounts to support cgroups v2, which are
added here
* https://github.com/coreos/fedora-coreos-tracker/issues/292
* https://github.com/coreos/fedora-coreos-tracker/issues/881
* https://github.com/cilium/cilium/pull/16259
