Check the release note of Kubernetes 1.18

[yokaze]

What

To conform to kubernetes 1.18, check the release note of this version.

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md

How

Read it and pick the necessary actions. Necessary actions should be listed as comments for this issue.

e.g. https://app.zenhub.com/workspaces/neco-5ca28d055128c041a68c0a8f/issues/cybozu-go/neco/828

Checklist

• [x] Finish implementation of the issue
• [x] Test all functions
• [x] Have enough logs to trace activities
• [x] Notify developers of necessary actions

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#serverside-apply---beta-2

Server-side Apply was promoted to Beta in 1.16, but is now introducing a second Beta in 1.18. This new version will track and manage changes to fields of all new Kubernetes objects, allowing you to know what changed your resources and when.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#extending-ingress-with-and-replacing-a-deprecated-annotation-with-ingressclass kubernetes.io/ingress.class is deprecated and IngressClass is introduced as a replacement.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#sig-cli-introduces-kubectl-debug We need to enable EphemeralContainers feature gate to use kubectl debug.

[umezawatakeshi]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#kubectl We often assumes that kubectl run create Deployment. We have to fix those test code.

[umezawatakeshi]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#client-go We have to follow this modification, especially in cke and bmc-reverse-proxy. Context appears as a first argument.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#client-go We need to check metrics update.

[umezawatakeshi]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#other-api-changes CRD schema may be failed to applied. we have to fix them as needed.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#kube-scheduler-1 A task is already created: multiple scheduling profiles https://github.com/cybozu-go/neco/issues/988 Import settings as Go-typed objects.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#kube-scheduler-1

Scheduler Extenders can now be configured in the v1alpha2 component config

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#kube-proxy-1

Added kube-proxy flags --ipvs-tcp-timeout, --ipvs-tcpfin-timeout, --ipvs-udp-timeout to configure IPVS connection timeouts

Related to Coil v2.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#kube-proxy-1 We can use --detect-local-mode as NodeCIDR to optimize iptables and/or ipvs rules. (neco/etc/cke-template.yml) It is because we separate Pod and Service IP ranges.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#feature-2

DefaultConstraints can be specified for PodTopologySpread Plugin in the scheduler’s ComponentConfig

We need to enhance CKE cluster.yml to support cluster-level default constraints. https://kubernetes.io/docs/concepts/workloads/pods/pod-topology-spread-constraints/#cluster-level-default-constraints

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#feature-2

Kubectl/drain: add disable-eviction option.Force drain to use delete, even if eviction is supported. This will bypass checking PodDisruptionBudgets, and should be used with caution. Kubectl/drain: add skip-wait-for-delete-timeout option. If a pod’s DeletionTimestamp is older than N seconds, skip waiting for the pod. Seconds must be greater than 0 to skip.

We can utilize these options in automating reboot.

[yokaze]

PodTopologySpread plugin now excludes terminatingPods when making scheduling decisions.

Just FYI

[umezawatakeshi]

SafeSysctlWhitelist: add net.ipv4.ping_group_range

we can now send ping https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#feature-2

[yokaze]

EvenPodsSpread is enabled by default in 1.18. We need to remove the option utilization.

[umezawatakeshi]

The kubelet and the default docker runtime now support running ephemeral containers in the Linux process namespace of a target container. Other container runtimes must implement support for this feature before it will be available for that runtime.

We use containerd instead of Docker. evaluation is requred.

[umezawatakeshi]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#dependencies-7

pause container should be updated. Also, we should not use master.

[yokaze]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.18.md#other-bug-cleanup-or-flake

k8s v1.18.1 also has some metrics name change. We need to check them.