- Fixed issue where `kubectl-convert` would fail when encountering resources that could not be converted to the specified api version. New behavior is to warn the user of the failed conversions and continue to convert the remaining resources. ([#117002](https://github.com/kubernetes/kubernetes/pull/117002), [@gxwilkerson33](https://github.com/gxwilkerson33))

### <a href="https://marshmallow.readthedocs.io/en/3.0/" class="external-link" target="_blank">Marshmallow</a>

APIシステムで必要とされる主な機能の一つに、コード (Python) からデータを取り出して、ネットワークを介して送れるものに変換するデータの「<abbr title="marshalling, conversion">シリアライゼーション</abbr>」があります。例えば、データベースのデータを含むオブジェクトをJSONオブジェクトに変換したり、`datetime` オブジェクトを文字列に変換するなどです。

- The `build-tag` flag is reintroduced to conversion-gen and defaulter-gen which allow users to inject custom build tag during code generation process. ([#128259](https://github.com/kubernetes/kubernetes/pull/128259), [@dinhxuanvu](https://github.com/dinhxuanvu)) [SIG API Machinery]

"+o]||l["* "+o]))for(i in l)if((s=i.split(" "))[1]===o&&(a=l[u+" "+s[0]]||l["* "+s[0]])){!0===a?a=l[i]:!0!==l[i]&&(o=s[0],c.unshift(s[1]));break}if(!0!==a)if(a&&e["throws"])t=a(t);else try{t=a(t)}catch(e){return{state:"parsererror",error:a?e:"No conversion from "+u+" to "+o}}}return{state:"success",data:t}}(v,s,T,i),i?(v.ifModified&&((u=T.getResponseHeader("Last-Modified"))&&(ce.lastModified[f]=u),(u=T.getResponseHeader("etag"))&&(ce.etag[f]=u)),204===e||"HEAD"===v.type?l="nocontent":304===e?l="n...

does not support protobuf encoding, if you roll back to 1.5 after upgrading to
protobuf you will be forced to restore from backup, and you will lose any changes
since you converted to protobuf.  After conversion to protobuf, you should
validate the correct operation of your cluster thoroughly before returning it
to normal operation.

Backups are always a good precaution, particularly around upgrades, but this

### SIG Cluster Lifecycle

  * kubeadm: The `:Etcd` struct has been refactored in the v1alpha2 API. All the options now reside under either `.Etcd.Local` or `.Etcd.External`. Automatic conversions from the v1alpha1 API are supported. ([#64066](https://github.com/kubernetes/kubernetes/pull/64066), [@luxas](https://github.com/luxas))

- Timeouts set in ListOptions for clients are also be respected locally ([#70998](https://github.com/kubernetes/kubernetes/pull/70998), [@deads2k](https://github.com/deads2k))
- Added support for CRD conversion webhook ([#67006](https://github.com/kubernetes/kubernetes/pull/67006), [@mbohlool](https://github.com/mbohlool))

"+f]||j["* "+f],!g)for(e in j)if(h=e.split(" "),h[1]===f&&(g=j[i+" "+h[0]]||j["* "+h[0]])){g===!0?g=j[e]:j[e]!==!0&&(f=h[0],k.unshift(h[1]));break}if(g!==!0)if(g&&a["throws"])b=g(b);else try{b=g(b)}catch(l){return{state:"parsererror",error:g?l:"No conversion from "+i+" to "+f}}}return{state:"success",data:b}}n.extend({active:0,lastModified:{},etag:{},ajaxSettings:{url:fc,type:"GET",isLocal:jc.test(ec[1]),global:!0,processData:!0,async:!0,contentType:"application/x-www-form-urlencoded; charset=UTF-8...

"+o]||l["* "+o]))for(i in l)if((s=i.split(" "))[1]===o&&(a=l[u+" "+s[0]]||l["* "+s[0]])){!0===a?a=l[i]:!0!==l[i]&&(o=s[0],c.unshift(s[1]));break}if(!0!==a)if(a&&e["throws"])t=a(t);else try{t=a(t)}catch(e){return{state:"parsererror",error:a?e:"No conversion from "+u+" to "+o}}}return{state:"success",data:t}}(v,s,T,i),i?(v.ifModified&&((u=T.getResponseHeader("Last-Modified"))&&(ce.lastModified[f]=u),(u=T.getResponseHeader("etag"))&&(ce.etag[f]=u)),204===e||"HEAD"===v.type?l="nocontent":304===e?l="n...

* Fix issue with kubectl annotate when --resource-version is provided. ([#29319](https://github.com/kubernetes/kubernetes/pull/29319), [@juanvallejo](https://github.com/juanvallejo))
* Reverted conversion of influx-db to Pet Set, it is now a Replication Controller. ([#30080](https://github.com/kubernetes/kubernetes/pull/30080), [@jszczepkowski](https://github.com/jszczepkowski))