Merge pull request #32205 from tengqm/zh-coredns

[zh] Update coredns page

content/zh/docs/tasks/administer-cluster/coredns.md

@@ -28,8 +28,10 @@ This page describes the CoreDNS upgrade process and how to install CoreDNS inste
 <!--
 ## About CoreDNS
 
-[CoreDNS](https://coredns.io) is a flexible, extensible DNS server that can serve as the Kubernetes cluster DNS.
+[CoreDNS](https://coredns.io) is a flexible, extensible DNS server
-Like Kubernetes, the CoreDNS project is hosted by the {{< glossary_tooltip text="CNCF" term_id="cncf" >}}.
+that can serve as the Kubernetes cluster DNS.
+Like Kubernetes, the CoreDNS project is hosted by the
+{{< glossary_tooltip text="CNCF" term_id="cncf" >}}.
 -->
 ## 关于 CoreDNS
 
@@ -37,11 +39,12 @@ Like Kubernetes, the CoreDNS project is hosted by the {{< glossary_tooltip text=
 与 Kubernetes 一样，CoreDNS 项目由 {{< glossary_tooltip text="CNCF" term_id="cncf" >}} 托管。
 
 <!--
-You can use CoreDNS instead of kube-dns in your cluster by replacing kube-dns in an existing
+You can use CoreDNS instead of kube-dns in your cluster by replacing
-deployment, or by using tools like kubeadm that will deploy and upgrade the cluster for you.
+kube-dns in an existing deployment, or by using tools like kubeadm
+that will deploy and upgrade the cluster for you.
 -->
-通过在现有的集群中替换 kube-dns，可以在集群中使用 CoreDNS 代替 kube-dns 部署，
+通过替换现有集群部署中的 kube-dns，或者使用 kubeadm 等工具来为你部署和升级集群，
-或者使用 kubeadm 等工具来为你部署和升级集群。
+可以在你的集群中使用 CoreDNS 而非 kube-dns，
 
 <!--
 ## Installing CoreDNS
@@ -52,105 +55,93 @@ For manual deployment or replacement of kube-dns, see the documentation at the
 ## 安装 CoreDNS
 
 有关手动部署或替换 kube-dns，请参阅
-[CoreDNS GitHub 工程](https://github.com/coredns/deployment/tree/master/kubernetes)。
+[CoreDNS GitHub 项目](https://github.com/coredns/deployment/tree/master/kubernetes)。
 
 <!--
 ## Migrating to CoreDNS
 
 ### Upgrading an existing cluster with kubeadm
 -->
-
 ## 迁移到 CoreDNS
 
 ### 使用 kubeadm 升级现有集群
 
 <!--
-In Kubernetes version 1.10 and later, you can also move to CoreDNS when you use `kubeadm` to upgrade
+In Kubernetes version 1.21, kubeadm removed its support for `kube-dns` as a DNS application.
-a cluster that is using `kube-dns`. In this case, `kubeadm` will generate the CoreDNS configuration
+For `kubeadm` v{{< skew currentVersion >}}, the only supported cluster DNS application
-("Corefile") based upon the `kube-dns` ConfigMap, preserving configurations for 
+is CoreDNS.
+-->
+在 Kubernetes 1.21 版本中，kubeadm 移除了对将 `kube-dns` 作为 DNS 应用的支持。
+对于 `kubeadm` v{{< skew currentVersion >}}，所支持的唯一的集群 DNS 应用是 CoreDNS。
+
+<!--
+You can move to CoreDNS when you use `kubeadm` to upgrade a cluster that is
+using `kube-dns`. In this case, `kubeadm` generates the CoreDNS configuration
+("Corefile") based upon the `kube-dns` ConfigMap, preserving configurations for
 stub domains, and upstream name server.
 -->
-在 Kubernetes 1.10 及更高版本中，当你使用 `kubeadm` 升级使用 `kube-dns` 的集群时，你还可以迁移到 CoreDNS。
+当你使用 `kubeadm` 升级使用 `kube-dns` 的集群时，你还可以执行到 CoreDNS 的迁移。
-在本例中 `kubeadm` 将生成 CoreDNS 配置（"Corefile"）基于 `kube-dns` ConfigMap，
+在这种场景中，`kubeadm` 将基于 `kube-dns` ConfigMap 生成 CoreDNS 配置（"Corefile"），
 保存存根域和上游名称服务器的配置。
 
-<!--
-If you are moving from kube-dns to CoreDNS, make sure to set the `CoreDNS` feature gate to `true`
-during an upgrade. For example, here is what a `v1.11.0` upgrade would look like:
--->
-如果你正在从 kube-dns 迁移到 CoreDNS，请确保在升级期间将 `CoreDNS` 特性门设置为 `true`。
-例如，`v1.11.0` 升级应该是这样的:
-
-```
-kubeadm upgrade apply v1.11.0 --feature-gates=CoreDNS=true
-```
-
-<!--
-In Kubernetes version 1.13 and later the `CoreDNS` feature gate is removed and CoreDNS
-is used by default. 
--->
-在 Kubernetes 版本 1.13 和更高版本中，`CoreDNS`特性门已经删除，CoreDNS 在默认情况下使用。
-
-<!--
-In versions prior to 1.11 the Corefile will be **overwritten** by the one created during upgrade.
-**You should save your existing ConfigMap if you have customized it.** You may re-apply your
-customizations after the new ConfigMap is up and running.
--->
-在 1.11 之前的版本中，核心文件将被升级过程中创建的文件覆盖。
-**如果已对其进行自定义，则应保存现有的 ConfigMap。** 
-在新的 ConfigMap 启动并运行后，你可以重新应用自定义。
-
-<!--
-If you are running CoreDNS in Kubernetes version 1.11 and later, during upgrade,
-your existing Corefile will be retained.
--->
-如果你在 Kubernetes 1.11 及更高版本中运行 CoreDNS，则在升级期间，将保留现有的 Corefile。
-
-<!--
-In Kubernetes version 1.21, support for `kube-dns` is removed from kubeadm.
--->
-在 kubernetes 1.21 中，kubeadm 移除了对 `kube-dns` 的支持。
-
 <!--
 ## Upgrading CoreDNS 
 
-CoreDNS is available in Kubernetes since v1.9. 
+You can check the version of CoreDNS that kubeadm installs for each version of
-You can check the version of CoreDNS shipped with Kubernetes and the changes made to CoreDNS [here](https://github.com/coredns/deployment/blob/master/kubernetes/CoreDNS-k8s_version.md).
+Kubernetes in the page
+[CoreDNS version in Kubernetes](https://github.com/coredns/deployment/blob/master/kubernetes/CoreDNS-k8s_version.md).
 -->
 ## 升级 CoreDNS 
 
-从 v1.9 起，Kubernetes 提供了 CoreDNS。
+你可以在 [CoreDNS version in Kubernetes](https://github.com/coredns/deployment/blob/master/kubernetes/CoreDNS-k8s_version.md)
-你可以在[此处](https://github.com/coredns/deployment/blob/master/kubernetes/CoreDNS-k8s_version.md)
+页面查看 kubeadm 为不同版本 Kubernetes 所安装的 CoreDNS 版本。
-查看 Kubernetes 随附的 CoreDNS 版本以及对 CoreDNS 所做的更改。
 
 <!--
-CoreDNS can be upgraded manually in case you want to only upgrade CoreDNS or use your own custom image.
+CoreDNS can be upgraded manually in case you want to only upgrade CoreDNS
-There is a helpful [guideline and walkthrough](https://github.com/coredns/deployment/blob/master/kubernetes/Upgrading_CoreDNS.md) available to ensure a smooth upgrade.
+or use your own custom image.
+There is a helpful [guideline and walkthrough](https://github.com/coredns/deployment/blob/master/kubernetes/Upgrading_CoreDNS.md)
+available to ensure a smooth upgrade.
+Make sure the existing CoreDNS configuration ("Corefile") is retained when
+upgrading your cluster.
 -->
-如果你只想升级 CoreDNS 或使用自己的自定义镜像，则可以手动升级 CoreDNS。
+如果你只想升级 CoreDNS 或使用自己的定制镜像，也可以手动升级 CoreDNS。
 参看[指南和演练](https://github.com/coredns/deployment/blob/master/kubernetes/Upgrading_CoreDNS.md)
 文档了解如何平滑升级。
+在升级你的集群过程中，请确保现有 CoreDNS 的配置（"Corefile"）被保留下来。
 
+<!--
+If you are upgrading your cluster using the `kubeadm` tool, `kubeadm`
+can take care of retaining the existing CoreDNS configuration automatically.
+-->
+如果使用 `kubeadm` 工具来升级集群，则 `kubeadm` 可以自动处理保留现有 CoreDNS
+配置这一事项。
 
 <!--
 ## Tuning CoreDNS
 
-When resource utilisation is a concern, it may be useful to tune the configuration of CoreDNS. For more details, check out the
+When resource utilisation is a concern, it may be useful to tune
+the configuration of CoreDNS. For more details, check out the
 [documentation on scaling CoreDNS]((https://github.com/coredns/deployment/blob/master/kubernetes/Scaling_CoreDNS.md)).
 -->
 ## CoreDNS 调优
 
 当资源利用方面有问题时，优化 CoreDNS 的配置可能是有用的。
-有关详细信息，请参阅[有关扩缩 CoreDNS 的文档](https://github.com/coredns/deployment/blob/master/kubernetes/Scaling_CoreDNS.md)。
+有关详细信息，请参阅有关[扩缩 CoreDNS 的文档](https://github.com/coredns/deployment/blob/master/kubernetes/Scaling_CoreDNS.md)。
 
 ## {{% heading "whatsnext" %}}
 
 <!--
 You can configure [CoreDNS](https://coredns.io) to support many more use cases than
-kube-dns by modifying the `Corefile`. For more information, see the
+kube-dns does by modifying the CoreDNS configuration ("Corefile").
-[CoreDNS site](https://coredns.io/2017/05/08/custom-dns-entries-for-kubernetes/).
+For more information, see the [documentation](https://coredns.io/plugins/kubernetes/)
+for the `kubernetes` CoreDNS plugin, or read the 
+[Custom DNS Entries for Kubernetes](https://coredns.io/2017/05/08/custom-dns-entries-for-kubernetes/)
+in the CoreDNS blog.
 -->
-你可以通过修改 `Corefile` 来配置 [CoreDNS](https://coredns.io)，以支持比 kube-dns 更多的用例。
+你可以通过修改 CoreDNS 的配置（"Corefile"）来配置 [CoreDNS](https://coredns.io)，
-请参考 [CoreDNS 网站](https://coredns.io/2017/05/08/custom-dns-entries-for-kubernetes/)
+以支持比 kube-dns 更多的用例。
+请参考 `kubernetes` CoreDNS 插件的[文档](https://coredns.io/plugins/kubernetes/)
+或者 CoreDNS 博客上的博文
+[Custom DNS Entries for Kubernetes](https://coredns.io/2017/05/08/custom-dns-entries-for-kubernetes/)，
 以了解更多信息。