* Validate that cronjob names are 52 characters or less ([#52733](https://github.com/kubernetes/kubernetes/pull/52733), [@julia-stripe](https://github.com/julia-stripe))
* add readme file of ipvs ([#51937](https://github.com/kubernetes/kubernetes/pull/51937), [@Lion-Wei](https://github.com/Lion-Wei))



# v1.9.0-alpha.1

- Kubeadm: Some text in the `kubeadm upgrade plan` output has changed. If you have scripts or other automation that parses this output, please review these changes and update your scripts to account for the new output. ([#98728](https://github.com/kubernetes/kubernetes/pull/98728), [@stmcginnis](https://github.com/stmcginnis)) [SIG Cluster Lifecycle]

* add spelling checking script ([#59463](https://github.com/kubernetes/kubernetes/pull/59463), [@dixudx](https://github.com/dixudx))

- Added the `applyconfiguration` generator to the code-generator script that generates server-side apply configuration and client APIs ([#114987](https://github.com/kubernetes/kubernetes/pull/114987), [@astefanutti](https://github.com/astefanutti))

* Fix incorrect retry logic in scheduler ([#50106](https://github.com/kubernetes/kubernetes/pull/50106), [@julia-stripe](https://github.com/julia-stripe))
* Enforce explicit references to API group client interfaces in clientsets to avoid ambiguity. ([#49370](https://github.com/kubernetes/kubernetes/pull/49370), [@sttts](https://github.com/sttts))

  - scrape_error --> scrape_error
  - node_cpu_usage_seconds_total --> node_cpu_usage_seconds
  - node_memory_working_set_bytes --> node_memory_working_set_bytes
  - container_cpu_usage_seconds_total --> container_cpu_usage_seconds
  - container_memory_working_set_bytes --> container_memory_working_set_bytes
  - scrape_error --> scrape_error 

- Projects which use k8s.io/code-generator and invoke `generate-groups` or `generate-internal-groups.sh` have a new, simpler script (`kube_codegen.sh`) they can use.  The old scripts are deprecated but remain intact. ([#117262](https://github.com/kubernetes/kubernetes/pull/117262), [@thockin](https://github.com/thockin)) [SIG API Machinery and Instrumentation]

- Updated defaultbackend image to 1.5. Users should concentrate on updating scripts to the new version. ([#69120](https://github.com/kubernetes/kubernetes/pull/69120), [@aledbf](https://github.com/aledbf))

- Kubernetes is now built using go 1.17. ([#103692](https://github.com/kubernetes/kubernetes/pull/103692), [@justaugustus](https://github.com/justaugustus))
- Performs strict server side schema validation requests via the `fieldValidation=[Strict,Warn,Ignore]`. ([#105916](https://github.com/kubernetes/kubernetes/pull/105916), [@kevindelgado](https://github.com/kevindelgado))
- Promote `IPv6DualStack` feature to stable.

- Fix etcd version migration script in etcd image. ([#91925](https://github.com/kubernetes/kubernetes/pull/91925), [@wenjiaswe](https://github.com/wenjiaswe)) [SIG API Machinery]