416 lines
16 KiB
Markdown
416 lines
16 KiB
Markdown
---
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title: 自定义 DNS 服务
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content_type: task
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min-kubernetes-server-version: v1.12
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---
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<!--
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reviewers:
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- bowei
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- zihongz
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title: Customizing DNS Service
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content_type: task
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min-kubernetes-server-version: v1.12
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-->
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<!-- overview -->
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<!--
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This page explains how to configure your DNS
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{{< glossary_tooltip text="Pod(s)" term_id="pod" >}} and customize the
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DNS resolution process in your cluster.
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-->
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本页说明如何配置 DNS {{< glossary_tooltip text="Pod(s)" term_id="pod" >}}，以及定制集群中 DNS 解析过程。
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## {{% heading "prerequisites" %}}
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{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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<!--
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Your cluster must be running the CoreDNS add-on.
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[Migrating to CoreDNS](/docs/tasks/administer-cluster/coredns/#migrating-to-coredns)
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explains how to use `kubeadm` to migrate from `kube-dns`.
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-->
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你的集群必须运行 CoreDNS 插件。
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文档[迁移到 CoreDNS](/zh/docs/tasks/administer-cluster/coredns/#migrating-to-coredns)
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解释了如何使用 `kubeadm` 从 `kube-dns` 迁移到 CoreDNS。
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<!-- steps -->
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<!--
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## Introduction
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DNS is a built-in Kubernetes service launched automatically
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using the addon manager
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[cluster add-on](https://releases.k8s.io/{{< param "githubbranch" >}}/cluster/addons/README.md).
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-->
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## 介绍
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DNS 是使用[集群插件](https://releases.k8s.io/{{< param "githubbranch" >}}/cluster/addons/README.md)
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管理器自动启动的内置的 Kubernetes 服务。
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<!--
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As of Kubernetes v1.12, CoreDNS is the recommended DNS Server, replacing kube-dns. If your cluster
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originally used kube-dns, you may still have `kube-dns` deployed rather than CoreDNS.
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-->
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从 Kubernetes v1.12 开始，CoreDNS 是推荐的 DNS 服务器，取代了 kube-dns。 如果
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你的集群原来使用 kube-dns，你可能部署的仍然是 `kube-dns` 而不是 CoreDNS。
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<!--
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Both the CoreDNS and kube-dns Service are named `kube-dns` in the `metadata.name` field.
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This is so that there is greater interoperability with workloads that relied on the legacy `kube-dns` Service name to resolve addresses internal to the cluster. Using a Service named `kube-dns` abstracts away the implementation detail of which DNS provider is running behind that common name.
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-->
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{{< note >}}
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CoreDNS 和 kube-dns 的 Service 都在其 `metadata.name` 字段使用名字 `kube-dns`。
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这是为了能够与依靠传统 `kube-dns` 服务名称来解析集群内部地址的工作负载具有更好的互操作性。
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使用 `kube-dns` 作为服务名称可以抽离共有名称之后运行的是哪个 DNS 提供程序这一实现细节。
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{{< /note >}}
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<!--
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If you are running CoreDNS as a Deployment, it will typically be exposed as a Kubernetes Service with a static IP address.
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The kubelet passes DNS resolver information to each container with the `-cluster-dns=<dns-service-ip>` flag.
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-->
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如果你在使用 Deployment 运行 CoreDNS，则该 Deployment 通常会向外暴露为一个具有
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静态 IP 地址 Kubernetes 服务。
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kubelet 使用 `--cluster-dns=<DNS 服务 IP>` 标志将 DNS 解析器的信息传递给每个容器。
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<!--
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DNS names also need domains. You configure the local domain in the kubelet
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with the flag `-cluster-domain=<default-local-domain>`.
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-->
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DNS 名称也需要域名。 你可在 kubelet 中使用 `--cluster-domain=<默认本地域名>`
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标志配置本地域名。
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<!--
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The DNS server supports forward lookups (A and AAAA records), port lookups (SRV records), reverse IP address lookups (PTR records),
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and more. For more information, see [DNS for Services and Pods](/docs/concepts/services-networking/dns-pod-service/).
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-->
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DNS 服务器支持正向查找（A 和 AAAA 记录）、端口发现（SRV 记录）、反向 IP 地址发现（PTR 记录）等。
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更多信息，请参见[Pod 和 服务的 DNS](/zh/docs/concepts/services-networking/dns-pod-service/)。
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<!--
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If a Pod's `dnsPolicy` is set to "`default`", it inherits the name resolution
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configuration from the node that the Pod runs on. The Pod's DNS resolution
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should behave the same as the node.
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But see [Known issues](/docs/tasks/administer-cluster/dns-debugging-resolution/#known-issues).
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-->
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如果 Pod 的 `dnsPolicy` 设置为 "`default`"，则它将从 Pod 运行所在节点继承名称解析配置。
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Pod 的 DNS 解析行为应该与节点相同。
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但请参阅[已知问题](/zh/docs/tasks/administer-cluster/dns-debugging-resolution/#known-issues)。
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<!--
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If you don't want this, or if you want a different DNS config for pods, you can
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use the kubelet's `-resolv-conf` flag. Set this flag to "" to prevent Pods from
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inheriting DNS. Set it to a valid file path to specify a file other than
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`/etc/resolv.conf` for DNS inheritance.
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-->
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如果你不想这样做，或者想要为 Pod 使用其他 DNS 配置，则可以
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使用 kubelet 的 `--resolv-conf` 标志。 将此标志设置为 "" 可以避免 Pod 继承 DNS。
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将其设置为有别于 `/etc/resolv.conf` 的有效文件路径可以设定 DNS 继承不同的配置。
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## CoreDNS
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<!--
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CoreDNS is a general-purpose authoritative DNS server that can serve as cluster DNS, complying with the [dns specifications]
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(https://github.com/kubernetes/dns/blob/master/docs/specification.md).
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-->
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CoreDNS 是通用的权威 DNS 服务器，可以用作集群 DNS，符合
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[DNS 规范](https://github.com/kubernetes/dns/blob/master/docs/specification.md)。
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<!--
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### CoreDNS ConfigMap options
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CoreDNS is a DNS server that is modular and pluggable, and each plugin adds new functionality to CoreDNS.
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This can be configured by maintaining a [Corefile](https://coredns.io/2017/07/23/corefile-explained/), which is the CoreDNS
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configuration file. A cluster administrator can modify the ConfigMap for the CoreDNS Corefile to change how service discovery works.
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-->
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### CoreDNS ConfigMap 选项 {#coredns-configmap-options}
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CoreDNS 是模块化且可插拔的 DNS 服务器，每个插件都为 CoreDNS 添加了新功能。
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可以通过维护 [Corefile](https://coredns.io/2017/07/23/corefile-explained/)，即 CoreDNS 配置文件，
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来定制其行为。 集群管理员可以修改 CoreDNS Corefile 的 ConfigMap，以更改服务发现的工作方式。
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<!--
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In Kubernetes, CoreDNS is installed with the following default Corefile configuration.
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-->
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在 Kubernetes 中，CoreDNS 安装时使用如下默认 Corefile 配置。
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```yaml
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: coredns
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namespace: kube-system
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data:
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Corefile: |
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.:53 {
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errors
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health {
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lameduck 5s
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}
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ready
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kubernetes cluster.local in-addr.arpa ip6.arpa {
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pods insecure
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fallthrough in-addr.arpa ip6.arpa
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ttl 30
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}
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prometheus :9153
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forward . /etc/resolv.conf
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cache 30
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loop
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reload
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loadbalance
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}
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```
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<!--
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The Corefile configuration includes the following [plugins](https://coredns.io/plugins/) of CoreDNS:
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-->
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Corefile 配置包括以下 CoreDNS [插件](https://coredns.io/plugins/)：
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<!--
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* [errors](https://coredns.io/plugins/errors/): Errors are logged to stdout.
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* [health](https://coredns.io/plugins/health/): Health of CoreDNS is reported to http://localhost:8080/health.
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* [kubernetes](https://coredns.io/plugins/kubernetes/): CoreDNS will reply to DNS queries based on IP of the services and pods of Kubernetes. You can find more details [here](https://coredns.io/plugins/kubernetes/).
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-->
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* [errors](https://coredns.io/plugins/errors/)：错误记录到标准输出。
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* [health](https://coredns.io/plugins/health/)：在 http://localhost:8080/health 处提供 CoreDNS 的健康报告。
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* [ready](https://coredns.io/plugins/ready/)：在端口 8181 上提供的一个 HTTP 末端，当所有能够
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表达自身就绪的插件都已就绪时，在此末端返回 200 OK。
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* [kubernetes](https://coredns.io/plugins/kubernetes/)：CoreDNS 将基于 Kubernetes 的服务和 Pod 的
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IP 答复 DNS 查询。你可以在 CoreDNS 网站阅读[更多细节](https://coredns.io/plugins/kubernetes/)。
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你可以使用 `ttl` 来定制响应的 TTL。默认值是 5 秒钟。TTL 的最小值可以是 0 秒钟，
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最大值为 3600 秒。将 TTL 设置为 0 可以禁止对 DNS 记录进行缓存。
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<!--
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The `pods insecure` option is provided for backward compatibility with kube-dns. You can use the
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`pods verified` option, which returns an A record only if there exists a pod in same namespace
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with matching IP. The `pods disabled` option can be used if you don't use pod records.
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-->
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`pods insecure` 选项是为了与 kube-dns 向后兼容。你可以使用 `pods verified` 选项，该选项使得
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仅在相同名称空间中存在具有匹配 IP 的 Pod 时才返回 A 记录。如果你不使用 Pod 记录，则可以使用
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`pods disabled` 选项。
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<!--
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* [prometheus](https://coredns.io/plugins/prometheus/): Metrics of CoreDNS are available at http://localhost:9153/metrics in [Prometheus](https://prometheus.io/) format.
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* [forward](https://coredns.io/plugins/forward/): Any queries that are not within the cluster domain of Kubernetes will be forwarded to predefined resolvers (/etc/resolv.conf).
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* [cache](https://coredns.io/plugins/cache/): This enables a frontend cache.
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* [loop](https://coredns.io/plugins/loop/): Detects simple forwarding loops and halts the CoreDNS process if a loop is found.
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* [reload](https://coredns.io/plugins/reload): Allows automatic reload of a changed Corefile. After you edit the ConfigMap configuration, allow two minutes for your changes to take effect.
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* [loadbalance](https://coredns.io/plugins/loadbalance): This is a round-robin DNS loadbalancer that randomizes the order of A, AAAA, and MX records in the answer.
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-->
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* [prometheus](https://coredns.io/plugins/prometheus/)：CoreDNS 的度量指标值以
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[Prometheus](https://prometheus.io/) 格式在 http://localhost:9153/metrics 上提供。
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* [forward](https://coredns.io/plugins/forward/): 不在 Kubernetes 集群域内的任何查询都将转发到
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预定义的解析器 (/etc/resolv.conf).
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* [cache](https://coredns.io/plugins/cache/)：启用前端缓存。
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* [loop](https://coredns.io/plugins/loop/)：检测到简单的转发环，如果发现死循环，则中止 CoreDNS 进程。
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* [reload](https://coredns.io/plugins/reload)：允许自动重新加载已更改的 Corefile。
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编辑 ConfigMap 配置后，请等待两分钟，以使更改生效。
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* [loadbalance](https://coredns.io/plugins/loadbalance)：这是一个轮转式 DNS 负载均衡器，
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它在应答中随机分配 A、AAAA 和 MX 记录的顺序。
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<!--
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You can modify the default CoreDNS behavior by modifying the ConfigMap.
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-->
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你可以通过修改 ConfigMap 来更改默认的 CoreDNS 行为。
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<!--
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### Configuration of Stub-domain and upstream nameserver using CoreDNS
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CoreDNS has the ability to configure stubdomains and upstream nameservers using the [forward plugin](https://coredns.io/plugins/forward/).
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-->
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### 使用 CoreDNS 配置存根域和上游域名服务器
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CoreDNS 能够使用 [forward 插件](https://coredns.io/plugins/forward/)配置存根域和上游域名服务器。
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<!--
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#### Example
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If a cluster operator has a [Consul](https://www.consul.io/) domain server located at 10.150.0.1, and all Consul names have the suffix .consul.local. To configure it in CoreDNS, the cluster administrator creates the following stanza in the CoreDNS ConfigMap.
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-->
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#### 示例
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如果集群操作员在 10.150.0.1 处运行了 [Consul](https://www.consul.io/) 域服务器，
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且所有 Consul 名称都带有后缀 `.consul.local`。要在 CoreDNS 中对其进行配置，
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集群管理员可以在 CoreDNS 的 ConfigMap 中创建加入以下字段。
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```
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consul.local:53 {
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errors
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cache 30
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forward . 10.150.0.1
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}
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```
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<!--
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To explicitly force all non-cluster DNS lookups to go through a specific nameserver at 172.16.0.1, point the `forward` to the nameserver instead of `/etc/resolv.conf`
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-->
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要显式强制所有非集群 DNS 查找通过特定的域名服务器（位于 172.16.0.1），可将 `forward`
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指向该域名服务器，而不是 `/etc/resolv.conf`。
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```
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forward . 172.16.0.1
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```
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<!--
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The final ConfigMap along with the default `Corefile` configuration looks like:
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-->
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最终的包含默认的 `Corefile` 配置的 ConfigMap 如下所示：
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```yaml
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: coredns
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namespace: kube-system
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data:
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Corefile: |
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.:53 {
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errors
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health
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kubernetes cluster.local in-addr.arpa ip6.arpa {
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pods insecure
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fallthrough in-addr.arpa ip6.arpa
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}
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prometheus :9153
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forward . 172.16.0.1
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cache 30
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loop
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reload
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loadbalance
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}
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consul.local:53 {
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errors
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cache 30
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forward . 10.150.0.1
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}
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```
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<!--
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The `kubeadm` supports automatic translation of the CoreDNS ConfigMap from the kube-dns ConfigMap.
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-->
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工具 `kubeadm` 支持将 kube-dns ConfigMap 自动转换为 CoreDNS ConfigMap。
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<!--
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While kube-dns accepts an FQDN for stubdomain and nameserver (eg: ns.foo.com), CoreDNS does not support this feature.
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During translation, all FQDN nameservers will be omitted from the CoreDNS config.***
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-->
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{{< note >}}
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尽管 kube-dns 接受 FQDN（例如：ns.foo.com）作为存根域和名字服务器，CoreDNS 不支持此功能。
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转换期间，CoreDNS 配置中将忽略所有的 FQDN 域名服务器。
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{{< /note >}}
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<!--
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## CoreDNS configuration equivalent to kube-dns
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CoreDNS supports the features of kube-dns and more.
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A ConfigMap created for kube-dns to support `StubDomains`and `upstreamNameservers` translates to the `proxy` plugin in CoreDNS.
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Similarly, the `Federations` plugin in kube-dns translates to the `federation` plugin in CoreDNS.
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### Example
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This example ConfigMap for kubedns specifies federations, stubdomains and upstreamnameservers:
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-->
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## CoreDNS 配置等同于 kube-dns
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CoreDNS 不仅仅提供 kube-dns 的功能。
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为 kube-dns 创建的 ConfigMap 支持 `StubDomains` 和 `upstreamNameservers` 转换为 CoreDNS 中的 `forward` 插件。
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同样，kube-dns 中的 `Federations` 插件会转换为 CoreDNS 中的 `federation` 插件。
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### 示例
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用于 kubedns 的此示例 ConfigMap 描述了 federations、stubdomains and upstreamnameservers：
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```yaml
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apiVersion: v1
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data:
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federations: |
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{"foo" : "foo.feddomain.com"}
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stubDomains: |
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{"abc.com" : ["1.2.3.4"], "my.cluster.local" : ["2.3.4.5"]}
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upstreamNameservers: |
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["8.8.8.8", "8.8.4.4"]
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kind: ConfigMap
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```
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<!--
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The equivalent configuration in CoreDNS creates a Corefile:
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-->
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CoreDNS 中的等效配置将创建一个 Corefile：
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* 针对 federations:
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```yaml
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federation cluster.local {
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foo foo.feddomain.com
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}
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```
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* 针对 stubDomains:
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```yaml
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abc.com:53 {
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errors
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cache 30
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proxy . 1.2.3.4
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}
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my.cluster.local:53 {
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errors
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cache 30
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proxy . 2.3.4.5
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}
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```
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<!--
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The complete Corefile with the default plugins:
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-->
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带有默认插件的完整 Corefile：
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```
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.:53 {
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errors
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health
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kubernetes cluster.local in-addr.arpa ip6.arpa {
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pods insecure
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fallthrough in-addr.arpa ip6.arpa
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}
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federation cluster.local {
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foo foo.feddomain.com
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}
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prometheus :9153
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forward . 8.8.8.8 8.8.4.4
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cache 30
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}
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abc.com:53 {
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errors
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cache 30
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forward . 1.2.3.4
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}
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my.cluster.local:53 {
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errors
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cache 30
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forward . 2.3.4.5
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}
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```
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<!--
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## Migration to CoreDNS
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To migrate from kube-dns to CoreDNS, [a detailed blog](https://coredns.io/2018/05/21/migration-from-kube-dns-to-coredns/) is available to help users adapt CoreDNS in place of kube-dns.
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A cluster administrator can also migrate using [the deploy script](https://github.com/coredns/deployment/blob/master/kubernetes/deploy.sh).
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|
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-->
|
||
## 迁移到 CoreDNS
|
||
|
||
要从 kube-dns 迁移到 CoreDNS，[此博客](https://coredns.io/2018/05/21/migration-from-kube-dns-to-coredns/)
|
||
提供了帮助用户将 kube-dns 替换为 CoreDNS。
|
||
集群管理员还可以使用[部署脚本](https://github.com/coredns/deployment/blob/master/kubernetes/deploy.sh)
|
||
进行迁移。
|
||
|
||
## {{% heading "whatsnext" %}}
|
||
|
||
<!--
|
||
- Read [Debugging DNS Resolution](/docs/tasks/administer-cluster/dns-debugging-resolution/).
|
||
-->
|
||
- 阅读[调试 DNS 解析](/zh/docs/tasks/administer-cluster/dns-debugging-resolution/)
|
||
|