191 lines
4.8 KiB
Markdown
191 lines
4.8 KiB
Markdown
---
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title: 使用 HostAliases 向 Pod /etc/hosts 文件添加条目
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content_type: concept
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weight: 60
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min-kubernetes-server-version: 1.7
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---
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<!--
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reviewers:
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- rickypai
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- thockin
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title: Adding entries to Pod /etc/hosts with HostAliases
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content_type: concept
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weight: 60
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min-kubernetes-server-version: 1.7
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-->
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<!-- overview -->
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<!--
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Adding entries to a Pod's /etc/hosts file provides Pod-level override of hostname resolution when DNS and other options are not applicable. You can add these custom entries with the HostAliases field in PodSpec.
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Modification not using HostAliases is not suggested because the file is managed by Kubelet and can be overwritten on during Pod creation/restart.
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-->
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当 DNS 配置以及其它选项不合理的时候，通过向 Pod 的 /etc/hosts 文件中添加条目，
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可以在 Pod 级别覆盖对主机名的解析。你可以通过 PodSpec 的 HostAliases
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字段来添加这些自定义条目。
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建议通过使用 HostAliases 来进行修改，因为该文件由 Kubelet 管理，并且
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可以在 Pod 创建/重启过程中被重写。
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<!-- body -->
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<!--
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## Default Hosts File Content
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Start an Nginx Pod which is assigned a Pod IP:
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-->
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## 默认 hosts 文件内容
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让我们从一个 Nginx Pod 开始，该 Pod 被分配一个 IP：
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```shell
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kubectl run nginx --image nginx --generator=run-pod/v1
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```
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```
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pod/nginx created
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```
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<!--
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Examine a Pod IP:
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-->
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检查 Pod IP：
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```shell
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kubectl get pods --output=wide
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```
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```
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NAME READY STATUS RESTARTS AGE IP NODE
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nginx 1/1 Running 0 13s 10.200.0.4 worker0
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```
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<!--
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The hosts file content would look like this:
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-->
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主机文件的内容如下所示：
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```shell
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kubectl exec nginx -- cat /etc/hosts
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```
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```
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# Kubernetes-managed hosts file.
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127.0.0.1 localhost
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::1 localhost ip6-localhost ip6-loopback
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fe00::0 ip6-localnet
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fe00::0 ip6-mcastprefix
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fe00::1 ip6-allnodes
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fe00::2 ip6-allrouters
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10.200.0.4 nginx
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```
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<!--
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By default, the `hosts` file only includes IPv4 and IPv6 boilerplates like
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`localhost` and its own hostname.
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-->
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默认情况下，hosts 文件只包含 IPv4 和 IPv6 的样板内容，像 `localhost` 和主机名称。
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<!--
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## Adding Additional Entries with HostAliases
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In addition to the default boilerplate, we can add additional entries to the
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`hosts` file.
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For example: to resolve `foo.local`, `bar.local` to `127.0.0.1` and `foo.remote`,
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`bar.remote` to `10.1.2.3`, we can configure HostAliases for a Pod under
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`.spec.hostAliases`:
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-->
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## 通过 HostAliases 增加额外条目
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除了默认的样板内容，我们可以向 hosts 文件添加额外的条目。
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例如，要将 `foo.local`、`bar.local` 解析为 `127.0.0.1`，
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将 `foo.remote`、 `bar.remote` 解析为 `10.1.2.3`，我们可以在
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`.spec.hostAliases` 下为 Pod 配置 HostAliases。
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{{< codenew file="service/networking/hostaliases-pod.yaml" >}}
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<!--
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You can start a Pod with that configuration by running:
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-->
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你可以使用以下命令用此配置启动 Pod：
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```shell
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kubectl apply -f hostaliases-pod.yaml
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```
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```
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pod/hostaliases-pod created
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```
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<!--
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Examine a Pod's details to see its IPv4 address and its status:
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-->
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检查 Pod 详情，查看其 IPv4 地址和状态：
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```shell
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kubectl get pod --output=wide
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```
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```
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NAME READY STATUS RESTARTS AGE IP NODE
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hostaliases-pod 0/1 Completed 0 6s 10.200.0.5 worker0
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```
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<!--
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The `hosts` file content looks like this:
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-->
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hosts 文件的内容看起来类似如下这样：
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```shell
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kubectl logs hostaliases-pod
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```
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```
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# Kubernetes-managed hosts file.
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127.0.0.1 localhost
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::1 localhost ip6-localhost ip6-loopback
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fe00::0 ip6-localnet
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fe00::0 ip6-mcastprefix
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fe00::1 ip6-allnodes
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fe00::2 ip6-allrouters
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10.200.0.5 hostaliases-pod
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# Entries added by HostAliases.
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127.0.0.1 foo.local bar.local
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10.1.2.3 foo.remote bar.remote
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```
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<!--
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With the additional entries specified at the bottom.
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-->
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在最下面额外添加了一些条目。
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<!--
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## Why Does Kubelet Manage the Hosts File?
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Kubelet [manages](https://github.com/kubernetes/kubernetes/issues/14633) the
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`hosts` file for each container of the Pod to prevent Docker from
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[modifying](https://github.com/moby/moby/issues/17190) the file after the
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containers have already been started.
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-->
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## 为什么 kubelet 管理 hosts 文件？
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kubelet [管理](https://github.com/kubernetes/kubernetes/issues/14633) Pod
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中每个容器的 hosts 文件，避免 Docker 在容器已经启动之后去
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[修改](https://github.com/moby/moby/issues/17190) 该文件。
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{{< caution >}}
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<!--
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Avoid making manual changes to the hosts file inside a container.
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If you make manual changes to the hosts file,
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those changes are lost when the container exits.
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-->
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请避免手工更改容器内的 hosts 文件内容。
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如果你对 hosts 文件做了手工修改，这些修改都会在容器退出时丢失。
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{{< /caution >}}
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