181 lines
4.9 KiB
Markdown
181 lines
4.9 KiB
Markdown
---
|
||
title: 使用 HostAliases 向 Pod /etc/hosts 文件添加条目
|
||
content_template: templates/concept
|
||
weight: 60
|
||
---
|
||
|
||
{{< toc >}}
|
||
|
||
{{% capture overview %}}
|
||
|
||
<!--
|
||
Adding entries to a Pod's /etc/hosts file provides Pod-level override of hostname resolution when DNS and other options are not applicable. In 1.7, users can add these custom entries with the HostAliases field in PodSpec.
|
||
|
||
Modification not using HostAliases is not suggested because the file is managed by Kubelet and can be overwritten on during Pod creation/restart.
|
||
-->
|
||
|
||
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，可以在 Pod 级别覆盖对主机名的解析。在 1.7 版本，用户可以通过 PodSpec 的 HostAliases 字段来添加这些自定义的条目。
|
||
|
||
建议通过使用 HostAliases 来进行修改，因为该文件由 Kubelet 管理，并且可以在 Pod 创建/重启过程中被重写。
|
||
{{% /capture %}}
|
||
|
||
{{% capture body %}}
|
||
|
||
<!--
|
||
## Default Hosts File Content
|
||
|
||
Let's start an Nginx Pod which is assigned a Pod IP:
|
||
-->
|
||
## 默认 hosts 文件内容
|
||
|
||
让我们从一个 Nginx Pod 开始，给该 Pod 分配一个 IP：
|
||
|
||
```shell
|
||
kubectl run nginx --image nginx --generator=run-pod/v1
|
||
```
|
||
|
||
```shell
|
||
pod/nginx created
|
||
```
|
||
|
||
<!--
|
||
Examine a Pod IP:
|
||
-->
|
||
检查Pod IP：
|
||
|
||
```shell
|
||
kubectl get pods --output=wide
|
||
```
|
||
|
||
```shell
|
||
NAME READY STATUS RESTARTS AGE IP NODE
|
||
nginx 1/1 Running 0 13s 10.200.0.4 worker0
|
||
```
|
||
|
||
<!--
|
||
The hosts file content would look like this:
|
||
-->
|
||
|
||
主机文件的内容如下所示：
|
||
|
||
```shell
|
||
kubectl exec nginx -- cat /etc/hosts
|
||
```
|
||
|
||
```none
|
||
# Kubernetes-managed hosts file.
|
||
127.0.0.1 localhost
|
||
::1 localhost ip6-localhost ip6-loopback
|
||
fe00::0 ip6-localnet
|
||
fe00::0 ip6-mcastprefix
|
||
fe00::1 ip6-allnodes
|
||
fe00::2 ip6-allrouters
|
||
10.200.0.4 nginx
|
||
```
|
||
|
||
<!--
|
||
By default, the `hosts` file only includes IPv4 and IPv6 boilerplates like
|
||
`localhost` and its own hostname.
|
||
-->
|
||
默认，hosts 文件只包含 ipv4 和 ipv6 的样板内容，像 `localhost` 和主机名称。
|
||
|
||
<!--
|
||
## Adding Additional Entries with HostAliases
|
||
|
||
In addition to the default boilerplate, we can add additional entries to the
|
||
`hosts` file to resolve `foo.local`, `bar.local` to `127.0.0.1` and `foo.remote`,
|
||
`bar.remote` to `10.1.2.3`, we can by adding HostAliases to the Pod under
|
||
`.spec.hostAliases`:
|
||
-->
|
||
|
||
## 通过 HostAliases 增加额外的条目
|
||
|
||
除了默认的样板内容，我们可以向 hosts 文件添加额外的条目，将 `foo.local`、 `bar.local` 解析为`127.0.0.1`，
|
||
将 `foo.remote`、 `bar.remote` 解析为 `10.1.2.3`，我们可以在 `.spec.hostAliases` 下为 Pod 添加 HostAliases。
|
||
|
||
{{< codenew file="service/networking/hostaliases-pod.yaml" >}}
|
||
|
||
<!--
|
||
This Pod can be started with the following commands:
|
||
-->
|
||
|
||
可以使用以下命令启动此Pod：
|
||
|
||
```shell
|
||
kubectl apply -f hostaliases-pod.yaml
|
||
```
|
||
|
||
```shell
|
||
pod/hostaliases-pod created
|
||
```
|
||
|
||
<!--
|
||
Examine a Pod IP and status:
|
||
-->
|
||
检查Pod IP 和状态：
|
||
|
||
```shell
|
||
kubectl get pod --output=wide
|
||
```
|
||
|
||
```shell
|
||
NAME READY STATUS RESTARTS AGE IP NODE
|
||
hostaliases-pod 0/1 Completed 0 6s 10.200.0.5 worker0
|
||
```
|
||
|
||
<!--
|
||
The `hosts` file content would look like this:
|
||
-->
|
||
|
||
hosts 文件的内容看起来类似如下这样：
|
||
|
||
```shell
|
||
kubectl logs hostaliases-pod
|
||
```
|
||
|
||
```none
|
||
# Kubernetes-managed hosts file.
|
||
127.0.0.1 localhost
|
||
::1 localhost ip6-localhost ip6-loopback
|
||
fe00::0 ip6-localnet
|
||
fe00::0 ip6-mcastprefix
|
||
fe00::1 ip6-allnodes
|
||
fe00::2 ip6-allrouters
|
||
10.200.0.5 hostaliases-pod
|
||
|
||
# Entries added by HostAliases.
|
||
127.0.0.1 foo.local bar.local
|
||
10.1.2.3 foo.remote bar.remote
|
||
```
|
||
|
||
<!--
|
||
With the additional entries specified at the bottom.
|
||
-->
|
||
|
||
在最下面额外添加了一些条目。
|
||
|
||
<!--
|
||
With the additional entries specified at the bottom.
|
||
|
||
## Why Does Kubelet Manage the Hosts File?
|
||
|
||
Kubelet [manages](https://github.com/kubernetes/kubernetes/issues/14633) the
|
||
`hosts` file for each container of the Pod to prevent Docker from
|
||
[modifying](https://github.com/moby/moby/issues/17190) the file after the
|
||
containers have already been started.
|
||
|
||
Because of the managed-nature of the file, any user-written content will be
|
||
overwritten whenever the `hosts` file is remounted by Kubelet in the event of
|
||
a container restart or a Pod reschedule. Thus, it is not suggested to modify
|
||
the contents of the file.
|
||
-->
|
||
|
||
## 为什么 Kubelet 管理 hosts文件？
|
||
|
||
kubelet [管理](https://github.com/kubernetes/kubernetes/issues/14633) Pod 中每个容器的 hosts 文件，避免 Docker 在容器已经启动之后去 [修改](https://github.com/moby/moby/issues/17190) 该文件。
|
||
|
||
因为该文件是托管性质的文件，无论容器重启或 Pod 重新调度，用户修改该 hosts 文件的任何内容，都会在 Kubelet 重新安装后被覆盖。因此，不建议修改该文件的内容。
|
||
|
||
{{% /capture %}}
|
||
|