---
title: 镜像
content_type: concept
weight: 10
---
<!--
reviewers:
- erictune
- thockin
title: Images
content_type: concept
weight: 10
-->

<!-- overview -->

<!--
A container image represents binary data that encapsulates an application and all its
software dependencies. Container images are executable software bundles that can run
standalone and that make very well defined assumptions about their runtime environment.

You typically create a container image of your application and push it to a registry
before referring to it in a
{{< glossary_tooltip text="Pod" term_id="pod" >}}

This page provides an outline of the container image concept.
-->
容器镜像（Image）所承载的是封装了应用程序及其所有软件依赖的二进制数据。
容器镜像是可执行的软件包，可以单独运行；该软件包对所处的运行时环境具有
良定（Well Defined）的假定。

你通常会创建应用的容器镜像并将其推送到某仓库（Registry），然后在
{{< glossary_tooltip text="Pod" term_id="pod" >}} 中引用它。

本页概要介绍容器镜像的概念。

<!-- body -->

<!--
## Image names

Container images are usually given a name such as `pause`, `example/mycontainer`, or `kube-apiserver`.
Images can also include a registry hostname; for example: `fictional.registry.example/imagename`,
and possibly a port number as well; for example: `fictional.registry.example:10443/imagename`.

If you don't specify a registry hostname, Kubernetes assumes that you mean the Docker public registry.

After the image name part you can add a _tag_ (in the same way you would when using with commands like `docker` or `podman`).
Tags let you identify different versions of the same series of images.
-->
## 镜像名称    {#image-names}

容器镜像通常会被赋予 `pause`、`example/mycontainer` 或者 `kube-apiserver` 这类的名称。
镜像名称也可以包含所在仓库的主机名。例如：`fictional.registry.example/imagename`。
还可以包含仓库的端口号，例如：`fictional.registry.example:10443/imagename`。

如果你不指定仓库的主机名，Kubernetes 认为你在使用 Docker 公共仓库。

在镜像名称之后，你可以添加一个标签（Tag）（与使用 `docker` 或 `podman` 等命令时的方式相同）。
使用标签能让你辨识同一镜像序列中的不同版本。

<!--
Image tags consist of lowercase and uppercase letters, digits, underscores (`_`),
periods (`.`), and dashes (`-`).  
There are additional rules about where you can place the separator
characters (`_`, `-`, and `.`) inside an image tag.  
If you don't specify a tag, Kubernetes assumes you mean the tag `latest`.
-->
镜像标签可以包含小写字母、大写字母、数字、下划线（`_`）、句点（`.`）和连字符（`-`）。
关于在镜像标签中何处可以使用分隔字符（`_`、`-` 和 `.`）还有一些额外的规则。
如果你不指定标签，Kubernetes 认为你想使用标签 `latest`。

<!--
## Updating images

When you first create a {{< glossary_tooltip text="Deployment" term_id="deployment" >}},
{{< glossary_tooltip text="StatefulSet" term_id="statefulset" >}}, Pod, or other
object that includes a Pod template, then by default the pull policy of all
containers in that pod will be set to `IfNotPresent` if it is not explicitly
specified. This policy causes the
{{< glossary_tooltip text="kubelet" term_id="kubelet" >}} to skip pulling an
image if it already exists.
-->
## 更新镜像  {#updating-images}

当你最初创建一个 {{< glossary_tooltip text="Deployment" term_id="deployment" >}}、
{{< glossary_tooltip text="StatefulSet" term_id="statefulset" >}}、Pod
或者其他包含 Pod 模板的对象时，如果没有显式设定的话，Pod 中所有容器的默认镜像
拉取策略是 `IfNotPresent`。这一策略会使得
{{< glossary_tooltip text="kubelet" term_id="kubelet" >}}
在镜像已经存在的情况下直接略过拉取镜像的操作。

<!--
### Image pull policy

The `imagePullPolicy` for a container and the tag of the image affect when the
[kubelet](/docs/reference/command-line-tools-reference/kubelet/) attempts to pull (download) the specified image.

Here's a list of the values you can set for `imagePullPolicy` and the effects
these values have:
-->
### 镜像拉取策略   {#image-pull-policy}

容器的 `imagePullPolicy` 和镜像的标签会影响 [kubelet](/zh-cn/docs/reference/command-line-tools-reference/kubelet/) 尝试拉取（下载）指定的镜像。

以下列表包含了 `imagePullPolicy` 可以设置的值，以及这些值的效果：

<!--
`IfNotPresent`
: the image is pulled only if it is not already present locally.

`Always`
: every time the kubelet launches a container, the kubelet queries the container
  image registry to resolve the name to an image
  [digest](https://docs.docker.com/engine/reference/commandline/pull/#pull-an-image-by-digest-immutable-identifier). If the kubelet has a
  container image with that exact digest cached locally, the kubelet uses its cached
  image; otherwise, the kubelet pulls the image with the resolved digest,
  and uses that image to launch the container.

`Never`
: the kubelet does not try fetching the image. If the image is somehow already present
  locally, the kubelet attempts to start the container; otherwise, startup fails.
  See [pre-pulled images](#pre-pulled-images) for more details.
-->
`IfNotPresent`
: 只有当镜像在本地不存在时才会拉取。

`Always`
: 每当 kubelet 启动一个容器时，kubelet 会查询容器的镜像仓库，
  将名称解析为一个镜像[摘要](https://docs.docker.com/engine/reference/commandline/pull/#pull-an-image-by-digest-immutable-identifier)。
  如果 kubelet 有一个容器镜像，并且对应的摘要已在本地缓存，kubelet 就会使用其缓存的镜像；
  否则，kubelet 就会使用解析后的摘要拉取镜像，并使用该镜像来启动容器。

`Never`
: Kubelet 不会尝试获取镜像。如果镜像已经以某种方式存在本地，
  kubelet 会尝试启动容器；否则，会启动失败。
  更多细节见[提前拉取镜像](#pre-pulled-images)。

<!--
The caching semantics of the underlying image provider make even
`imagePullPolicy: Always` efficient, as long as the registry is reliably accessible.
Your container runtime can notice that the image layers already exist on the node
so that they don't need to be downloaded again.
-->
只要能够可靠地访问镜像仓库，底层镜像提供者的缓存语义甚至可以使 `imagePullPolicy: Always` 高效。
你的容器运行时可以注意到节点上已经存在的镜像层，这样就不需要再次下载。

<!--
You should avoid using the `:latest` tag when deploying containers in production as
it is harder to track which version of the image is running and more difficult to
roll back properly.

Instead, specify a meaningful tag such as `v1.42.0`.

To make sure the Pod always uses the same version of a container image, you can specify
the image's digest;
replace `<image-name>:<tag>` with `<image-name>@<digest>`
(for example, `image@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2`).
-->
{{< note >}}
在生产环境中部署容器时，你应该避免使用 `:latest` 标签，因为这使得正在运行的镜像的版本难以追踪，并且难以正确地回滚。

相反，应指定一个有意义的标签，如 `v1.42.0`。
{{< /note >}}

为了确保 Pod 总是使用相同版本的容器镜像，你可以指定镜像的摘要；
将 `<image-name>:<tag>` 替换为 `<image-name>@<digest>`，例如 `image@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2`。

<!--
When using image tags, if the image registry were to change the code that the tag on that image represents, you might end up with a mix of Pods running the old and new code. An image digest uniquely identifies a specific version of the image, so Kubernetes runs the same code every time it starts a container with that image name and digest specified. Specifying an image by digest fixes the code that you run so that a change at the registry cannot lead to that mix of versions.

There are third-party [admission controllers](/docs/reference/access-authn-authz/admission-controllers/)
that mutate Pods (and pod templates) when they are created, so that the
running workload is defined based on an image digest rather than a tag.
That might be useful if you want to make sure that all your workload is
running the same code no matter what tag changes happen at the registry.
-->
当使用镜像标签时，如果镜像仓库修改了代码所对应的镜像标签，可能会出现新旧代码混杂在 Pod 中运行的情况。
镜像摘要唯一标识了镜像的特定版本，因此 Kubernetes 每次启动具有指定镜像名称和摘要的容器时，都会运行相同的代码。
通过摘要指定镜像可固定你运行的代码，这样镜像仓库的变化就不会导致版本的混杂。

有一些第三方的[准入控制器](/zh-cn/docs/reference/access-authn-authz/admission-controllers/)
在创建 Pod（和 Pod 模板）时产生变更，这样运行的工作负载就是根据镜像摘要，而不是标签来定义的。
无论镜像仓库上的标签发生什么变化，你都想确保你所有的工作负载都运行相同的代码，那么指定镜像摘要会很有用。

<!-- 
#### Default image pull policy {#imagepullpolicy-defaulting}

When you (or a controller) submit a new Pod to the API server, your cluster sets the
`imagePullPolicy` field when specific conditions are met:
-->
#### 默认镜像拉取策略    {#imagepullpolicy-defaulting}

当你（或控制器）向 API 服务器提交一个新的 Pod 时，你的集群会在满足特定条件时设置 `imagePullPolicy `字段：

<!--
- if you omit the `imagePullPolicy` field, and the tag for the container image is
  `:latest`, `imagePullPolicy` is automatically set to `Always`;
- if you omit the `imagePullPolicy` field, and you don't specify the tag for the
  container image, `imagePullPolicy` is automatically set to `Always`;
- if you omit the `imagePullPolicy` field, and you specify the tag for the
  container image that isn't `:latest`, the `imagePullPolicy` is automatically set to
  `IfNotPresent`.
-->
- 如果你省略了 `imagePullPolicy` 字段，并且容器镜像的标签是 `:latest`，
  `imagePullPolicy` 会自动设置为 `Always`。
- 如果你省略了 `imagePullPolicy` 字段，并且没有指定容器镜像的标签，
  `imagePullPolicy` 会自动设置为 `Always`。
- 如果你省略了 `imagePullPolicy` 字段，并且为容器镜像指定了非 `:latest` 的标签，
  `imagePullPolicy` 就会自动设置为 `IfNotPresent`。

{{< note >}}
<!--
The value of `imagePullPolicy` of the container is always set when the object is
first _created_, and is not updated if the image's tag later changes.

For example, if you create a Deployment with an image whose tag is _not_
`:latest`, and later update that Deployment's image to a `:latest` tag, the
`imagePullPolicy` field will _not_ change to `Always`. You must manually change
the pull policy of any object after its initial creation.
-->
容器的 `imagePullPolicy` 的值总是在对象初次 _创建_ 时设置的，如果后来镜像的标签发生变化，则不会更新。

例如，如果你用一个 _非_ `:latest` 的镜像标签创建一个 Deployment，
并在随后更新该 Deployment 的镜像标签为 `:latest`，则 `imagePullPolicy` 字段 _不会_ 变成 `Always`。
你必须手动更改已经创建的资源的拉取策略。
{{< /note >}}

<!--
#### Required image pull

If you would like to always force a pull, you can do one of the following:

- Set the `imagePullPolicy` of the container to `Always`.
- Omit the `imagePullPolicy` and use `:latest` as the tag for the image to use;
  Kubernetes will set the policy to `Always` when you submit the Pod.
- Omit the `imagePullPolicy` and the tag for the image to use;
  Kubernetes will set the policy to `Always` when you submit the Pod.
- Enable the [AlwaysPullImages](/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages) admission controller.
-->
#### 必要的镜像拉取   {#required-image-pull}

如果你想总是强制执行拉取，你可以使用下述的一中方式：

- 设置容器的 `imagePullPolicy` 为 `Always`。
- 省略 `imagePullPolicy`，并使用 `:latest` 作为镜像标签；
  当你提交 Pod 时，Kubernetes 会将策略设置为 `Always`。
- 省略 `imagePullPolicy` 和镜像的标签；
  当你提交 Pod 时，Kubernetes 会将策略设置为 `Always`。
- 启用准入控制器 [AlwaysPullImages](/zh-cn/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages)。


<!--
### ImagePullBackOff

When a kubelet starts creating containers for a Pod using a container runtime,
it might be possible the container is in [Waiting](/docs/concepts/workloads/pods/pod-lifecycle/#container-state-waiting)
state because of `ImagePullBackOff`.
-->
### ImagePullBackOff

当 kubelet 使用容器运行时创建 Pod 时，容器可能因为 `ImagePullBackOff` 导致状态为
[Waiting](/zh-cn/docs/concepts/workloads/pods/pod-lifecycle/#container-state-waiting)。

<!--
The status `ImagePullBackOff` means that a container could not start because Kubernetes
could not pull a container image (for reasons such as invalid image name, or pulling
from a private registry without `imagePullSecret`). The `BackOff` part indicates
that Kubernetes will keep trying to pull the image, with an increasing back-off delay.

Kubernetes raises the delay between each attempt until it reaches a compiled-in limit,
which is 300 seconds (5 minutes).
-->
`ImagePullBackOff` 状态意味着容器无法启动，
因为 Kubernetes 无法拉取容器镜像（原因包括无效的镜像名称，或从私有仓库拉取而没有 `imagePullSecret`）。
 `BackOff` 部分表示 Kubernetes 将继续尝试拉取镜像，并增加回退延迟。

Kubernetes 会增加每次尝试之间的延迟，直到达到编译限制，即 300 秒（5 分钟）。

<!--
## Multi-architecture images with image indexes

As well as providing binary images, a container registry can also serve a [container image index](https://github.com/opencontainers/image-spec/blob/master/image-index.md). An image index can point to multiple [image manifests](https://github.com/opencontainers/image-spec/blob/master/manifest.md) for architecture-specific versions of a container. The idea is that you can have a name for an image (for example: `pause`, `example/mycontainer`, `kube-apiserver`) and allow different systems to fetch the right binary image for the machine architecture they are using.

Kubernetes itself typically names container images with a suffix `-$(ARCH)`. For backward compatibility, please generate the older images with suffixes. The idea is to generate say `pause` image which has the manifest for all the arch(es) and say `pause-amd64` which is backwards compatible for older configurations or YAML files which may have hard coded the images with suffixes.
-->
## 带镜像索引的多架构镜像  {#multi-architecture-images-with-image-indexes}

除了提供二进制的镜像之外，容器仓库也可以提供
[容器镜像索引](https://github.com/opencontainers/image-spec/blob/master/image-index.md)。
镜像索引可以根据特定于体系结构版本的容器指向镜像的多个
[镜像清单](https://github.com/opencontainers/image-spec/blob/master/manifest.md)。
这背后的理念是让你可以为镜像命名（例如：`pause`、`example/mycontainer`、`kube-apiserver`）
的同时，允许不同的系统基于它们所使用的机器体系结构取回正确的二进制镜像。

Kubernetes 自身通常在命名容器镜像时添加后缀 `-$(ARCH)`。
为了向前兼容，请在生成较老的镜像时也提供后缀。
这里的理念是为某镜像（如 `pause`）生成针对所有平台都适用的清单时，
生成 `pause-amd64` 这类镜像，以便较老的配置文件或者将镜像后缀硬编码到其中的
YAML 文件也能兼容。

<!--
## Using a private registry

Private registries may require keys to read images from them.  
Credentials can be provided in several ways:
-->
## 使用私有仓库   {#using-a-private-registry}

从私有仓库读取镜像时可能需要密钥。
凭证可以用以下方式提供:

<!--
  - Configuring Nodes to Authenticate to a Private Registry
    - all pods can read any configured private registries
    - requires node configuration by cluster administrator
  - Pre-pulled Images
    - all pods can use any images cached on a node
    - requires root access to all nodes to setup
  - Specifying ImagePullSecrets on a Pod
    - only pods which provide own keys can access the private registry
  - Vendor-specific or local extensions
    - if you're using a custom node configuration, you (or your cloud
      provider) can implement your mechanism for authenticating the node
      to the container registry.
-->
- 配置节点向私有仓库进行身份验证
  - 所有 Pod 均可读取任何已配置的私有仓库
  - 需要集群管理员配置节点
- 预拉镜像
  - 所有 Pod 都可以使用节点上缓存的所有镜像
  - 需要所有节点的 root 访问权限才能进行设置
- 在 Pod 中设置 ImagePullSecrets
  - 只有提供自己密钥的 Pod 才能访问私有仓库
- 特定于厂商的扩展或者本地扩展
  - 如果你在使用定制的节点配置，你（或者云平台提供商）可以实现让节点
    向容器仓库认证的机制

<!--
These options are explained in more detail below.
-->
下面将详细描述每一项。

<!--
### Configuring nodes to authenticate to a private registry

Specific instructions for setting credentials depends on the container runtime and registry you chose to use. You should refer to your solution's documentation for the most accurate information.
-->
### 配置 Node 对私有仓库认证

设置凭据的具体说明取决于你选择使用的容器运行时和仓库。
你应该参考解决方案的文档来获取最准确的信息。

<!--
Default Kubernetes only supports the `auths` and `HttpHeaders` section in Docker configuration.
Docker credential helpers (`credHelpers` or `credsStore`) are not supported.
-->
{{< note >}}
Kubernetes 默认仅支持 Docker 配置中的 `auths` 和 `HttpHeaders` 部分，
不支持 Docker 凭据辅助程序（`credHelpers` 或 `credsStore`）。
{{< /note >}}

<!--
For an example of configuring a private container image registry, see the
[Pull an Image from a Private Registry](/docs/tasks/configure-pod-container/pull-image-private-registry)
task. That example uses a private registry in Docker Hub.
-->
有关配置私有容器镜像仓库的示例，请参阅任务
[从私有镜像库中拉取镜像](/zh-cn/docs/tasks/configure-pod-container/pull-image-private-registry)。
该示例使用 Docker Hub 中的私有注册表。

<!--
### Interpretation of config.json {#config-json}
-->
### config.json 说明 {#config-json}

<!--
The interpretation of `config.json` varies between the original Docker
implementation and the Kubernetes interpretation. In Docker, the `auths` keys
can only specify root URLs, whereas Kubernetes allows glob URLs as well as
prefix-matched paths. This means that a `config.json` like this is valid:
-->
对于 `config.json` 的解释在原始 Docker 实现和 Kubernetes 的解释之间有所不同。
在 Docker 中，`auths` 键只能指定根 URL ，而 Kubernetes 允许 glob URLs 以及
前缀匹配的路径。这意味着，像这样的 `config.json` 是有效的：
```json
{
    "auths": {
        "*my-registry.io/images": {
            "auth": "…"
        }
    }
}
```

<!--
The root URL (`*my-registry.io`) is matched by using the following syntax:

```
pattern:
    { term }

term:
    '*'         matches any sequence of non-Separator characters
    '?'         matches any single non-Separator character
    '[' [ '^' ] { character-range } ']'
                character class (must be non-empty)
    c           matches character c (c != '*', '?', '\\', '[')
    '\\' c      matches character c

character-range:
    c           matches character c (c != '\\', '-', ']')
    '\\' c      matches character c
    lo '-' hi   matches character c for lo <= c <= hi
```
-->
使用以下语法匹配根 URL （`*my-registry.io`）：
```
pattern:
    { term }

term:
    '*'         匹配任何无分隔符字符序列
    '?'         匹配任意单个非分隔符
    '[' [ '^' ] 字符范围
                  字符集（必须非空）
    c           匹配字符 c （c 不为 '*','?','\\','['）
    '\\' c      匹配字符 c

字符范围: 
    c           匹配字符 c （c 不为 '\\','?','-',']'）
    '\\' c      匹配字符 c
    lo '-' hi   匹配字符范围在 lo 到 hi 之间字符
```

<!--
Image pull operations would now pass the credentials to the CRI container
runtime for every valid pattern. For example the following container image names
would match successfully:

- `my-registry.io/images`
- `my-registry.io/images/my-image`
- `my-registry.io/images/another-image`
- `sub.my-registry.io/images/my-image`
- `a.sub.my-registry.io/images/my-image`
-->
现在镜像拉取操作会将每种有效模式的凭据都传递给 CRI 容器运行时。例如下面的容器镜像名称会匹配成功：

- `my-registry.io/images`
- `my-registry.io/images/my-image`
- `my-registry.io/images/another-image`
- `sub.my-registry.io/images/my-image`
- `a.sub.my-registry.io/images/my-image`

<!--
The kubelet performs image pulls sequentially for every found credential. This
means, that multiple entries in `config.json` are possible, too:
-->
kubelet 为每个找到的凭证的镜像按顺序拉取。 这意味着在 `config.json` 中可能有多项：

```json
{
    "auths": {
        "my-registry.io/images": {
            "auth": "…"
        },
        "my-registry.io/images/subpath": {
            "auth": "…"
        }
    }
}
```

<!--
If now a container specifies an image `my-registry.io/images/subpath/my-image`
to be pulled, then the kubelet will try to download them from both
authentication sources if one of them fails.
-->
如果一个容器指定了要拉取的镜像 `my-registry.io/images/subpath/my-image`，
并且其中一个失败，kubelet 将尝试从另一个身份验证源下载镜像。

<!--
### Pre-pulled images
-->
### 提前拉取镜像   {#pre-pulled-images}

<!--
This approach is suitable if you can control node configuration.  It
will not work reliably if your cloud provider manages nodes and replaces
them automatically.
-->
{{< note >}}
该方法适用于你能够控制节点配置的场合。
如果你的云供应商负责管理节点并自动置换节点，这一方案无法可靠地工作。
{{< /note >}}

<!--
By default, the kubelet tries to pull each image from the specified registry.
However, if the `imagePullPolicy` property of the container is set to `IfNotPresent` or `Never`,
then a local image is used (preferentially or exclusively, respectively).
-->
默认情况下，`kubelet` 会尝试从指定的仓库拉取每个镜像。
但是，如果容器属性 `imagePullPolicy` 设置为 `IfNotPresent` 或者 `Never`，
则会优先使用（对应 `IfNotPresent`）或者一定使用（对应 `Never`）本地镜像。

<!--
If you want to rely on pre-pulled images as a substitute for registry authentication,
you must ensure all nodes in the cluster have the same pre-pulled images.

This can be used to preload certain images for speed or as an alternative to authenticating to a private registry.

All pods will have read access to any pre-pulled images.
-->
如果你希望使用提前拉取镜像的方法代替仓库认证，就必须保证集群中所有节点提前拉取的镜像是相同的。

这一方案可以用来提前载入指定的镜像以提高速度，或者作为向私有仓库执行身份认证的一种替代方案。

所有的 Pod 都可以使用节点上提前拉取的镜像。

<!--
### Specifying imagePullSecrets on a Pod
-->
### 在 Pod 上指定 ImagePullSecrets   {#specifying-imagepullsecrets-on-a-pod}

<!--
This is the recommended approach to run containers based on images
in private registries.
-->
{{< note >}}
运行使用私有仓库中镜像的容器时，建议使用这种方法。
{{< /note >}}

<!--
Kubernetes supports specifying container image registry keys on a Pod.
-->
Kubernetes 支持在 Pod 中设置容器镜像仓库的密钥。

<!--
#### Creating a Secret with a Docker config

You need to know the username, registry password and client email address for authenticating
to the registry, as well as its hostname.
Run the following command, substituting the appropriate uppercase values:
-->
#### 使用 Docker Config 创建 Secret   {#creating-a-secret-with-docker-config}

你需要知道用于向仓库进行身份验证的用户名、密码和客户端电子邮件地址，以及它的主机名。
运行以下命令，注意替换适当的大写值：

```shell
kubectl create secret docker-registry <name> --docker-server=DOCKER_REGISTRY_SERVER --docker-username=DOCKER_USER --docker-password=DOCKER_PASSWORD --docker-email=DOCKER_EMAIL
```

<!--
If you already have a Docker credentials file then, rather than using the above
command, you can import the credentials file as a Kubernetes
{{< glossary_tooltip text="Secrets" term_id="secret" >}}.  
[Create a Secret based on existing Docker credentials](/docs/tasks/configure-pod-container/pull-image-private-registry/#registry-secret-existing-credentials) explains how to set this up.
-->
如果你已经有 Docker 凭据文件，则可以将凭据文件导入为 Kubernetes
{{< glossary_tooltip text="Secret" term_id="secret" >}}，
而不是执行上面的命令。
[基于已有的 Docker 凭据创建 Secret](/zh-cn/docs/tasks/configure-pod-container/pull-image-private-registry/#registry-secret-existing-credentials)
解释了如何完成这一操作。

<!--
This is particularly useful if you are using multiple private container
registries, as `kubectl create secret docker-registry` creates a Secret that
only works with a single private registry.
-->
如果你在使用多个私有容器仓库，这种技术将特别有用。
原因是 `kubectl create secret docker-registry` 创建的是仅适用于某个私有仓库的 Secret。

<!--
Pods can only reference image pull secrets in their own namespace,
so this process needs to be done one time per namespace.
-->
{{< note >}}
Pod 只能引用位于自身所在名字空间中的 Secret，因此需要针对每个名字空间
重复执行上述过程。
{{< /note >}}

<!--
#### Referring to an imagePullSecrets on a Pod

Now, you can create pods which reference that secret by adding an `imagePullSecrets`
section to a Pod definition.

For example:
-->
#### 在 Pod 中引用 ImagePullSecrets

现在，在创建 Pod 时，可以在 Pod 定义中增加 `imagePullSecrets` 部分来引用该 Secret。

例如：

```shell
cat <<EOF > pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: foo
  namespace: awesomeapps
spec:
  containers:
    - name: foo
      image: janedoe/awesomeapp:v1
  imagePullSecrets:
    - name: myregistrykey
EOF

cat <<EOF >> ./kustomization.yaml
resources:
- pod.yaml
EOF
```

<!--
This needs to be done for each pod that is using a private registry.  

However, setting of this field can be automated by setting the imagePullSecrets
in a [ServiceAccount](/docs/tasks/configure-pod-container/configure-service-account/) resource.

Check [Add ImagePullSecrets to a Service Account](/docs/tasks/configure-pod-container/configure-service-account/#add-imagepullsecrets-to-a-service-account) for detailed instructions.

You can use this in conjunction with a per-node `.docker/config.json`.  The credentials
will be merged.
-->
你需要对使用私有仓库的每个 Pod 执行以上操作。
不过，设置该字段的过程也可以通过为
[服务账号](/zh-cn/docs/tasks/configure-pod-container/configure-service-account/)
资源设置 `imagePullSecrets` 来自动完成。
有关详细指令可参见
[将 ImagePullSecrets 添加到服务账号](/zh-cn/docs/tasks/configure-pod-container/configure-service-account/#add-imagepullsecrets-to-a-service-account)。

你也可以将此方法与节点级别的 `.docker/config.json` 配置结合使用。
来自不同来源的凭据会被合并。

<!--
## Use cases

There are a number of solutions for configuring private registries.  Here are some
common use cases and suggested solutions.
-->
## 使用案例  {#use-cases}

配置私有仓库有多种方案，以下是一些常用场景和建议的解决方案。

<!--
1. Cluster running only non-proprietary (e.g. open-source) images.  No need to hide images.
   - Use public images on the Docker hub.
     - No configuration required.
     - Some cloud providers automatically cache or mirror public images, which improves availability and reduces the time to pull images.
-->
1. 集群运行非专有镜像（例如，开源镜像）。镜像不需要隐藏。
   - 使用 Docker hub 上的公开镜像
     - 无需配置
     - 某些云厂商会自动为公开镜像提供高速缓存，以便提升可用性并缩短拉取镜像所需时间

<!--
1. Cluster running some proprietary images which should be hidden to those outside the company, but
   visible to all cluster users.
   - Use a hosted private [Docker registry](https://docs.docker.com/registry/).
     - It may be hosted on the [Docker Hub](https://hub.docker.com/signup), or elsewhere.
     - Manually configure .docker/config.json on each node as described above.
   - Or, run an internal private registry behind your firewall with open read access.
     - No Kubernetes configuration is required.
   - Use a hosted container image registry service that controls image access
     - It will work better with cluster autoscaling than manual node configuration.
   - Or, on a cluster where changing the node configuration is inconvenient, use `imagePullSecrets`.
-->
2. 集群运行一些专有镜像，这些镜像需要对公司外部隐藏，对所有集群用户可见
   - 使用托管的私有 [Docker 仓库](https://docs.docker.com/registry/)。
     - 可以托管在 [Docker Hub](https://hub.docker.com/account/signup/) 或者其他地方
     - 按照上面的描述，在每个节点上手动配置 `.docker/config.json` 文件
   - 或者，在防火墙内运行一个组织内部的私有仓库，并开放读取权限
     - 不需要配置 Kubenretes
   - 使用控制镜像访问的托管容器镜像仓库服务
     - 与手动配置节点相比，这种方案能更好地处理集群自动扩缩容
   - 或者，在不方便更改节点配置的集群中，使用 `imagePullSecrets`

<!--
1. Cluster with proprietary images, a few of which require stricter access control.
   - Ensure [AlwaysPullImages admission controller](/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages) is active. Otherwise, all Pods potentially have access to all images.
   - Move sensitive data into a "Secret" resource, instead of packaging it in an image.
-->
3. 集群使用专有镜像，且有些镜像需要更严格的访问控制
   - 确保 [AlwaysPullImages 准入控制器](/zh-cn/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages)被启用。否则，所有 Pod 都可以使用所有镜像。
   - 确保将敏感数据存储在 Secret 资源中，而不是将其打包在镜像里

<!--
1. A multi-tenant cluster where each tenant needs own private registry.
   - Ensure [AlwaysPullImages admission controller](/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages) is active. Otherwise, all Pods of all tenants potentially have access to all images.
   - Run a private registry with authorization required.
   - Generate registry credential for each tenant, put into secret, and populate secret to each tenant namespace.
   - The tenant adds that secret to imagePullSecrets of each namespace.
-->
4. 集群是多租户的并且每个租户需要自己的私有仓库
   - 确保 [AlwaysPullImages 准入控制器](/zh-cn/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages)。否则，所有租户的所有的 Pod 都可以使用所有镜像。
   - 为私有仓库启用鉴权
   - 为每个租户生成访问仓库的凭据，放置在 Secret 中，并将 Secrert 发布到各租户的命名空间下。
   - 租户将 Secret 添加到每个名字空间中的 imagePullSecrets

<!--
If you need access to multiple registries, you can create one secret for each registry.
Kubelet will merge any `imagePullSecrets` into a single virtual `.docker/config.json`
-->
如果你需要访问多个仓库，可以为每个仓库创建一个 Secret。
`kubelet` 将所有 `imagePullSecrets` 合并为一个虚拟的 `.docker/config.json` 文件。


## {{% heading "whatsnext" %}}

<!--
* Read the [OCI Image Manifest Specification](https://github.com/opencontainers/image-spec/blob/master/manifest.md).
* Learn about [container image garbage collection](/docs/concepts/architecture/garbage-collection/#container-image-garbage-collection).
-->
* 阅读 [OCI Image Manifest 规范](https://github.com/opencontainers/image-spec/blob/master/manifest.md)。
* 了解[容器镜像垃圾收集](/zh-cn/docs/concepts/architecture/garbage-collection/#container-image-garbage-collection)。