Merge pull request #46948 from a-mccarthy/kubernetes-1.31-deprecations-and-removals-blog

Add kubernetes 1.31 deprecations and removals blog

Author: k8s-ci-robot

content/en/blog/_posts/2024-07-19-kubernetes-1.31-deprecations-and-removals.md

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+---
+layout: blog
+title: 'Kubernetes Removals and Major Changes In v1.31'
+date: 2024-07-19
+slug: kubernetes-1-31-upcoming-changes
+author: >
+  Abigail McCarthy,
+  Edith Puclla,
+  Matteo Bianchi,
+  Rashan Smith,
+  Yigit Demirbas 
+---
+
+As Kubernetes develops and matures, features may be deprecated, removed, or replaced with better ones for the project's overall health. 
+This article outlines some planned changes for the Kubernetes v1.31 release that the release team feels you should be aware of for the continued maintenance of your Kubernetes environment. 
+The information listed below is based on the current status of the v1.31 release. 
+It may change before the actual release date. 
+
+## The Kubernetes API removal and deprecation process
+The Kubernetes project has a well-documented [deprecation policy](/docs/reference/using-api/deprecation-policy/) for features. 
+This policy states that stable APIs may only be deprecated when a newer, stable version of that API is available and that APIs have a minimum lifetime for each stability level.
+A deprecated API has been marked for removal in a future Kubernetes release. 
+It will continue to function until removal (at least one year from the deprecation), but usage will display a warning. 
+Removed APIs are no longer available in the current version, so you must migrate to using the replacement.
+
+* Generally available (GA) or stable API versions may be marked as deprecated but must not be removed within a major version of Kubernetes.
+
+* Beta or pre-release API versions must be supported for 3 releases after the deprecation.
+
+* Alpha or experimental API versions may be removed in any release without prior deprecation notice.
+
+Whether an API is removed because a feature graduated from beta to stable or because that API did not succeed, all removals comply with this deprecation policy. 
+Whenever an API is removed, migration options are communicated in the [documentation](/docs/reference/using-api/deprecation-guide/).
+
+## A note about SHA-1 signature support
+
+In [go1.18](https://go.dev/doc/go1.18#sha1) (released in March 2022), the crypto/x509 library started to reject certificates signed with a SHA-1 hash function. 
+While SHA-1 is established to be unsafe and publicly trusted Certificate Authorities have not issued SHA-1 certificates since 2015, there might still be cases in the context of Kubernetes where user-provided certificates are signed using a SHA-1 hash function through private authorities with them being used for Aggregated API Servers or webhooks. 
+If you have relied on SHA-1 based certificates, you must explicitly opt back into its support by setting `GODEBUG=x509sha1=1` in your environment.
+
+Given Go's [compatibility policy for GODEBUGs](https://go.dev/blog/compat), the `x509sha1` GODEBUG and the support for SHA-1 certificates will [fully go away in go1.24](https://tip.golang.org/doc/go1.23) which will be released in the first half of 2025. 
+If you rely on SHA-1 certificates, please start moving off them.
+
+Please see [Kubernetes issue #125689](https://github.com/kubernetes/kubernetes/issues/125689) to get a better idea of timelines around the support for SHA-1 going away, when Kubernetes releases plans to adopt go1.24, and for more details on how to detect usage of SHA-1 certificates via metrics and audit logging. 
+
+## Deprecations and removals in Kubernetes 1.31
+ 
+
+### Deprecation of `status.nodeInfo.kubeProxyVersion` field for Nodes ([KEP 4004](https://github.com/kubernetes/enhancements/issues/4004))
+
+The `.status.nodeInfo.kubeProxyVersion` field of Nodes is being deprecated in Kubernetes v1.31,
+and will be removed in a later release.
+It's being deprecated because the value of this field wasn't (and isn't) accurate.
+This field is set by the kubelet, which does not have reliable information about the kube-proxy version or whether kube-proxy is running. 
+
+The `DisableNodeKubeProxyVersion` [feature gate](/docs/reference/command-line-tools-reference/feature-gates/) will be set to `true` in by default in v1.31 and the kubelet will no longer attempt to set the `.status.kubeProxyVersion` field for its associated Node.
+
+### Removal of all in-tree integrations with cloud providers
+
+As highlighted in a [previous article](/blog/2024/05/20/completing-cloud-provider-migration/), the last remaining in-tree support for cloud provider integration will be removed as part of the v1.31 release.
+This doesn't mean you can't integrate with a cloud provider, however you now **must** use the
+recommended approach using an external integration. Some integrations are part of the Kubernetes
+project and others are third party software.
+
+This milestone marks the completion of the externalization process for all cloud providers' integrations from the Kubernetes core ([KEP-2395](https://github.com/kubernetes/enhancements/blob/master/keps/sig-cloud-provider/2395-removing-in-tree-cloud-providers/README.md)), a process started with Kubernetes v1.26. 
+This change helps Kubernetes to get closer to being a truly vendor-neutral platform.
+
+For further details on the cloud provider integrations, read our [v1.29 Cloud Provider Integrations feature blog](/blog/2023/12/14/cloud-provider-integration-changes/). 
+For additional context about the in-tree code removal, we invite you to check the ([v1.29 deprecation blog](/blog/2023/11/16/kubernetes-1-29-upcoming-changes/#removal-of-in-tree-integrations-with-cloud-providers-kep-2395-https-kep-k8s-io-2395)).
+
+The latter blog also contains useful information for users who need to migrate to version v1.29 and later.
+
+
+### Removal of kubelet `--keep-terminated-pod-volumes` command line flag
+
+The kubelet flag `--keep-terminated-pod-volumes`, which was deprecated in 2017, will be removed as
+part of the v1.31 release.
+
+You can find more details in the pull request [#122082](https://github.com/kubernetes/kubernetes/pull/122082).
+
+### Removal of CephFS volume plugin 
+
+[CephFS volume plugin](/docs/concepts/storage/volumes/#cephfs) was removed in this release and the `cephfs` volume type became non-functional. 
+
+It is recommended that you use the [CephFS CSI driver](https://github.com/ceph/ceph-csi/) as a third-party storage driver instead. If you were using the CephFS volume plugin before upgrading the cluster version to v1.31, you must re-deploy your application to use the new driver.
+
+CephFS volume plugin was formally marked as deprecated in v1.28.
+
+### Removal of Ceph RBD volume plugin
+
+The v1.31 release will remove the [Ceph RBD volume plugin](/docs/concepts/storage/volumes/#rbd) and its CSI migration support, making the `rbd` volume type non-functional.
+
+It's recommended that you use the [RBD CSI driver](https://github.com/ceph/ceph-csi/) in your clusters instead. 
+If you were using Ceph RBD volume plugin before upgrading the cluster version to v1.31, you must re-deploy your application to use the new driver.
+
+The Ceph RBD volume plugin was formally marked as deprecated in v1.28.
+
+### Deprecation of non-CSI volume limit plugins in kube-scheduler
+
+The v1.31 release will deprecate all non-CSI volume limit scheduler plugins, and will remove some
+already deprected plugins from the [default plugins](/docs/reference/scheduling/config/), including:
+
+- `AzureDiskLimits`
+- `CinderLimits`
+- `EBSLimits`
+- `GCEPDLimits`
+
+It's recommended that you use the `NodeVolumeLimits` plugin instead because it can handle the same functionality as the removed plugins since those volume types have been migrated to CSI. 
+Please replace the deprecated plugins with the `NodeVolumeLimits` plugin if you explicitly use them in the [scheduler config](/docs/reference/scheduling/config/). 
+The `AzureDiskLimits`, `CinderLimits`, `EBSLimits`, and `GCEPDLimits` plugins will be removed in a future release.
+
+These plugins will be removed from the default scheduler plugins list as they have been deprecated since Kubernetes v1.14.
+
+## Looking ahead
+The official list of API removals planned for [Kubernetes v1.32](/docs/reference/using-api/deprecation-guide/#v1-32) include:
+
+* The `flowcontrol.apiserver.k8s.io/v1beta3` API version of FlowSchema and PriorityLevelConfiguration will be removed. 
+To prepare for this, you can edit your existing manifests and rewrite client software to use the `flowcontrol.apiserver.k8s.io/v1 API` version, available since v1.29. 
+All existing persisted objects are accessible via the new API. Notable changes in flowcontrol.apiserver.k8s.io/v1beta3 include that the PriorityLevelConfiguration `spec.limited.nominalConcurrencyShares` field only defaults to 30 when unspecified, and an explicit value of 0 is not changed to 30.
+
+For more information, please refer to the [API deprecation guide](/docs/reference/using-api/deprecation-guide/#v1-32).
+
+## Want to know more?
+The Kubernetes release notes announce deprecations. 
+We will formally announce the deprecations in [Kubernetes v1.31](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.31.md#deprecation) as part of the CHANGELOG for that release.
+
+You can see the announcements of pending deprecations in the release notes for:
+
+* [Kubernetes v1.30](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.30.md#deprecation)
+
+* [Kubernetes v1.29](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.29.md#deprecation)
+
+* [Kubernetes v1.28](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.28.md#deprecation)
+
+* [Kubernetes v1.27](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.27.md#deprecation)
+
+