---
title: Secret
content_type: concept
feature:
  title: Secret 和配置管理
  description: >
    部署和更新 Secrets 和应用程序的配置而不必重新构建容器镜像，且
    不必将软件堆栈配置中的秘密信息暴露出来。
weight: 30
---
<!--
reviewers:
- mikedanese
title: Secrets
content_type: concept
feature:
  title: Secret and configuration management
  description: >
    Deploy and update secrets and application configuration without rebuilding your image
    and without exposing secrets in your stack configuration.
weight: 30
-->

<!-- overview -->

<!--
A Secret is an object that contains a small amount of sensitive data such as
a password, a token, or a key. Such information might otherwise be put in a
{{< glossary_tooltip term_id="pod" >}} specification or in a
{{< glossary_tooltip text="container image" term_id="image" >}}. Using a
Secret means that you don't need to include confidential data in your
application code.
-->
Secret 是一种包含少量敏感信息例如密码、令牌或密钥的对象。
这样的信息可能会被放在 {{< glossary_tooltip term_id="pod" >}} 规约中或者镜像中。
使用 Secret 意味着你不需要在应用程序代码中包含机密数据。

<!-- 
Because Secrets can be created independently of the Pods that use them, there
is less risk of the Secret (and its data) being exposed during the workflow of
creating, viewing, and editing Pods. Kubernetes, and applications that run in
your cluster, can also take additional precautions with Secrets, such as avoiding
writing confidential data to nonvolatile storage.

Secrets are similar to {{< glossary_tooltip text="ConfigMaps" term_id="configmap" >}}
but are specifically intended to hold confidential data.
-->
由于创建 Secret 可以独立于使用它们的 Pod，
因此在创建、查看和编辑 Pod 的工作流程中暴露 Secret（及其数据）的风险较小。
Kubernetes 和在集群中运行的应用程序也可以对 Secret 采取额外的预防措施，
例如避免将机密数据写入非易失性存储。

Secret 类似于 {{<glossary_tooltip text="ConfigMap" term_id="configmap" >}}
但专门用于保存机密数据。

{{< caution >}}
<!--
Kubernetes Secrets are, by default, stored unencrypted in the API server's underlying data store (etcd). Anyone with API access can retrieve or modify a Secret, and so can anyone with access to etcd.
Additionally, anyone who is authorized to create a Pod in a namespace can use that access to read any Secret in that namespace; this includes indirect access such as the ability to create a Deployment.

In order to safely use Secrets, take at least the following steps:

1. [Enable Encryption at Rest](/docs/tasks/administer-cluster/encrypt-data/) for Secrets.
1. Enable or configure [RBAC rules](/docs/reference/access-authn-authz/authorization/) that
   restrict reading and writing data in Secrets. Be aware that secrets can be obtained
   implicitly by anyone with the permission to create a Pod.
1. Where appropriate, also use mechanisms such as RBAC to limit which principals are allowed
   to create new Secrets or replace existing ones.
-->
默认情况下，Kubernetes Secret 未加密地存储在 API 服务器的底层数据存储（etcd）中。 
任何拥有 API 访问权限的人都可以检索或修改 Secret，任何有权访问 etcd 的人也可以。
此外，任何有权限在命名空间中创建 Pod 的人都可以使用该访问权限读取该命名空间中的任何 Secret；
这包括间接访问，例如创建 Deployment 的能力。

为了安全地使用 Secret，请至少执行以下步骤：

1. 为 Secret [启用静态加密](/zh/docs/tasks/administer-cluster/encrypt-data/)；
1. 启用或配置 [RBAC 规则](/zh/docs/reference/access-authn-authz/authorization/)来限制读取和写入
   Secret 的数据（包括通过间接方式）。需要注意的是，被准许创建 Pod 的人也隐式地被授权获取
   Secret 内容。
1. 在适当的情况下，还可以使用 RBAC 等机制来限制允许哪些主体创建新 Secret 或替换现有 Secret。
{{< /caution >}}

<!--
See [Information security for Secrets](#information-security-for-secrets) for more details.
-->
参见 [Secret 的信息安全](#information-security-for-secrets)了解详情。

<!-- body -->

<!--
## Uses for Secrets

There are three main ways for a Pod to use a Secret:
- As [files](#using-secrets-as-files-from-a-pod) in a
  {{< glossary_tooltip text="volume" term_id="volume" >}} mounted on one or more of
  its containers.
- As [container environment variable](#using-secrets-as-environment-variables).
- By the [kubelet when pulling images](#using-imagepullsecrets) for the Pod.

The Kubernetes control plane also uses Secrets; for example,
[bootstrap token Secrets](#bootstrap-token-secrets) are a mechanism to
help automate node registration.
-->
## Secret 的使用 {#uses-for-secrets}

Pod 可以用三种方式之一来使用 Secret：

- 作为挂载到一个或多个容器上的{{< glossary_tooltip text="卷" term_id="volume" >}}
  中的[文件](#using-secrets-as-files-from-a-pod)。
- 作为[容器的环境变量](#using-secrets-as-environment-variables)。
- 由 [kubelet 在为 Pod 拉取镜像时使用](#using-imagepullsecrets)。

Kubernetes 控制面也使用 Secret；
例如，[引导令牌 Secret](#bootstrap-token-secrets)
是一种帮助自动化节点注册的机制。

<!--
### Alternatives to Secrets

Rather than using a Secret to protect confidential data, you can pick from alternatives.

Here are some of your options:
-->
### Secret 的替代方案  {#alternatives-to-secrets}

除了使用 Secret 来保护机密数据，你也可以选择一些替代方案。

下面是一些选项：

<!--
- if your cloud-native component needs to authenticate to another application that you
  know is running within the same Kubernetes cluster, you can use a
  [ServiceAccount](/docs/reference/access-authn-authz/authentication/#service-account-tokens)
  and its tokens to identify your client.
- there are third-party tools that you can run, either within or outside your cluster,
  that provide secrets management. For example, a service that Pods access over HTTPS,
  that reveals a secret if the client correctly authenticates (for example, with a ServiceAccount
  token).
-->
- 如果你的云原生组件需要执行身份认证来访问你所知道的、在同一 Kubernetes 集群中运行的另一个应用，
  你可以使用 [ServiceAccount](/zh/docs/reference/access-authn-authz/authentication/#service-account-tokens)
  及其令牌来标识你的客户端身份。
- 你可以运行的第三方工具也有很多，这些工具可以运行在集群内或集群外，提供机密数据管理。
  例如，这一工具可能是 Pod 通过 HTTPS 访问的一个服务，该服务在客户端能够正确地通过身份认证
  （例如，通过 ServiceAccount 令牌）时，提供机密数据内容。
<!--
- for authentication, you can implement a custom signer for X.509 certificates, and use
  [CertificateSigningRequests](/docs/reference/access-authn-authz/certificate-signing-requests/)
  to let that custom signer issue certificates to Pods that need them.
- you can use a [device plugin](/docs/concepts/extend-kubernetes/compute-storage-net/device-plugins/)
  to expose node-local encryption hardware to a specific Pod. For example, you can schedule
  trusted Pods onto nodes that provide a Trusted Platform Module, configured out-of-band.
-->
- 就身份认证而言，你可以为 X.509 证书实现一个定制的签名者，并使用
  [CertificateSigningRequest](/zh/docs/reference/access-authn-authz/certificate-signing-requests/)
  来让该签名者为需要证书的 Pod 发放证书。
- 你可以使用一个[设备插件](/zh/docs/concepts/extend-kubernetes/compute-storage-net/device-plugins/)
  来将节点本地的加密硬件暴露给特定的 Pod。例如，你可以将可信任的 Pod
  调度到提供可信平台模块（Trusted Platform Module，TPM）的节点上。
  这类节点是另行配置的。

<!--
You can also combine two or more of those options, including the option to use Secret objects themselves.

For example: implement (or deploy) an {{< glossary_tooltip text="operator" term_id="operator-pattern" >}}
that fetches short-lived session tokens from an external service, and then creates Secrets based
on those short-lived session tokens. Pods running in your cluster can make use of the session tokens,
and operator ensures they are valid. This separation means that you can run Pods that are unaware of
the exact mechanisms for issuing and refreshing those session tokens.
-->
你还可以将如上选项的两种或多种进行组合，包括直接使用 Secret 对象本身也是一种选项。

例如：实现（或部署）一个 {{< glossary_tooltip text="operator" term_id="operator-pattern" >}}，
从外部服务取回生命期很短的会话令牌，之后基于这些生命期很短的会话令牌来创建 Secret。
运行在集群中的 Pod 可以使用这些会话令牌，而 Operator 则确保这些令牌是合法的。
这种责权分离意味着你可以运行那些不了解会话令牌如何发放与刷新的确切机制的 Pod。

<!--
## Working with Secrets

### Creating a Secret

There are several options to create a Secret:

- [create Secret using `kubectl` command](/docs/tasks/configmap-secret/managing-secret-using-kubectl/)
- [create Secret from config file](/docs/tasks/configmap-secret/managing-secret-using-config-file/)
- [create Secret using kustomize](/docs/tasks/configmap-secret/managing-secret-using-kustomize/)
-->
## 使用 Secret  {#working-with-secrets}

### 创建 Secret  {#creating-a-secret}

- [使用 `kubectl` 命令来创建 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-kubectl/)
- [基于配置文件来创建 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-config-file/)
- [使用 kustomize 来创建 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-kustomize/)

<!--
#### Constraints on Secret names and data {#restriction-names-data}

The name of a Secret object must be a valid
[DNS subdomain name](/docs/concepts/overview/working-with-objects/names#dns-subdomain-names).
-->
#### 对 Secret 名称与数据的约束 {#restriction-names-data}

Secret 对象的名称必须是合法的
[DNS 子域名](/zh/docs/concepts/overview/working-with-objects/names#dns-subdomain-names)。

<!--
You can specify the `data` and/or the `stringData` field when creating a
configuration file for a Secret.  The `data` and the `stringData` fields are optional.
The values for all keys in the `data` field have to be base64-encoded strings.
If the conversion to base64 string is not desirable, you can choose to specify
the `stringData` field instead, which accepts arbitrary strings as values.

The keys of `data` and `stringData` must consist of alphanumeric characters,
`-`, `_` or `.`. All key-value pairs in the `stringData` field are internally
merged into the `data` field. If a key appears in both the `data` and the
`stringData` field, the value specified in the `stringData` field takes
precedence.
-->
在为创建 Secret 编写配置文件时，你可以设置 `data` 与/或 `stringData` 字段。
`data` 和 `stringData` 字段都是可选的。`data` 字段中所有键值都必须是 base64
编码的字符串。如果不希望执行这种 base64 字符串的转换操作，你可以选择设置
`stringData` 字段，其中可以使用任何字符串作为其取值。

`data` 和 `stringData` 中的键名只能包含字母、数字、`-`、`_` 或 `.` 字符。
`stringData` 字段中的所有键值对都会在内部被合并到 `data` 字段中。
如果某个主键同时出现在 `data` 和 `stringData` 字段中，`stringData`
所指定的键值具有高优先级。

<!--
#### Size limit {#restriction-data-size}

Individual secrets are limited to 1MiB in size. This is to discourage creation
of very large secrets that could exhaust the API server and kubelet memory.
However, creation of many smaller secrets could also exhaust memory. You can
use a [resource quota](/docs/concepts/policy/resource-quotas/) to limit the
number of Secrets (or other resources) in a namespace.
-->
#### 尺寸限制   {#restriction-data-size}

每个 Secret 的尺寸最多为 1MiB。施加这一限制是为了避免用户创建非常大的 Secret，
进而导致 API 服务器和 kubelet 内存耗尽。不过创建很多小的 Secret 也可能耗尽内存。
你可以使用[资源配额](/zh/docs/concepts/policy/resource-quotas/)来约束每个名字空间中
Secret（或其他资源）的个数。

<!--
### Editing a Secret

You can edit an existing Secret using kubectl:
-->
### 编辑 Secret    {#editing-a-secret}

你可以使用 kubectl 来编辑一个已有的 Secret：

```shell
kubectl edit secrets mysecret
```

这一命令会启动你的默认编辑器，允许你更新 `data` 字段中存放的 base64 编码的 Secret 值；
例如：

```yaml
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file, it will be
# reopened with the relevant failures.
#
apiVersion: v1
data:
  username: YWRtaW4=
  password: MWYyZDFlMmU2N2Rm
kind: Secret
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: { ... }
  creationTimestamp: 2020-01-22T18:41:56Z
  name: mysecret
  namespace: default
  resourceVersion: "164619"
  uid: cfee02d6-c137-11e5-8d73-42010af00002
type: Opaque
```

<!--
That example manifest defines a Secret with two keys in the `data` field: `username` and `password`.
The values are Base64 strings in the manifest; however, when you use the Secret with a Pod
then the kubelet provides the _decoded_ data to the Pod and its containers.

You can package many keys and values into one Secret, or use many Secrets, whichever is convenient.
-->
这一示例清单定义了一个 Secret，其 `data` 字段中包含两个主键：`username` 和 `password`。
清单中的字段值是 Base64 字符串，不过，当你在 Pod 中使用 Secret 时，kubelet 为 Pod
及其中的容器提供的是解码后的数据。

你可以在一个 Secret 中打包多个主键和数值，也可以选择使用多个 Secret，
完全取决于哪种方式最方便。

<!--
### Using a Secret

Secrets can be mounted as data volumes or exposed as
{{< glossary_tooltip text="environment variables" term_id="container-env-variables" >}}
to be used by a container in a Pod. Secrets can also be used by other parts of the
system, without being directly exposed to the Pod. For example, Secrets can hold
credentials that other parts of the system should use to interact with external
systems on your behalf.
-->
### 使用 Secret    {#using-a-secret}

Secret 可以以数据卷的形式挂载，也可以作为{{< glossary_tooltip text="环境变量" term_id="container-env-variables" >}}
暴露给 Pod 中的容器使用。Secret 也可用于系统中的其他部分，而不是一定要直接暴露给 Pod。
例如，Secret 也可以包含系统中其他部分在替你与外部系统交互时要使用的凭证数据。

<!--
Secret volume sources are validated to ensure that the specified object
reference actually points to an object of type Secret. Therefore, a Secret
needs to be created before any Pods that depend on it.  

If the Secret cannot be fetched (perhaps because it does not exist, or
due to a temporary lack of connection to the API server) the kubelet
periodically retries running that Pod. The kubelet also reports an Event
for that Pod, including details of the problem fetching the Secret.
-->
Kubernetes 会检查 Secret 的卷数据源，确保所指定的对象引用确实指向类型为 Secret
的对象。因此，如果 Pod 依赖于某 Secret，该 Secret 必须先于 Pod 被创建。

如果 Secret 内容无法取回（可能因为 Secret 尚不存在或者临时性地出现 API
服务器网络连接问题），kubelet 会周期性地重试 Pod 运行操作。kubelet 也会为该 Pod
报告 Event 事件，给出读取 Secret 时遇到的问题细节。

<!--
#### Optional Secrets {#restriction-secret-must-exist}

When you define a container environment variable based on a Secret,
you can mark it as _optional_. The default is for the Secret to be
required.

None of a Pod's containers will start until all non-optional Secrets are
available.

If a Pod references a specific key in a Secret and that Secret does exist, but
is missing the named key, the Pod fails during startup.
-->
#### 可选的 Secret   {#restriction-secret-must-exist}

当你定义一个基于 Secret 的环境变量时，你可以将其标记为可选。
默认情况下，所引用的 Secret 都是必需的。

只有所有非可选的 Secret 都可用时，Pod 中的容器才能启动运行。

如果 Pod 引用了 Secret 中的特定主键，而虽然 Secret 本身存在，对应的主键不存在，
Pod 启动也会失败。

<!--
### Using Secrets as files from a Pod {#using-secrets-as-files-from-a-pod}

If you want to access data from a Secret in a Pod, one way to do that is to
have Kubernetes make the value of that Secret be available as a file inside
the filesystem of one or more of the Pod's containers.

To configure that, you:
-->
### 在 Pod 中以文件形式使用 Secret  {#using-secrets-as-files-from-a-pod}

如果你希望在 Pod 中访问 Secret 内的数据，一种方式是让 Kubernetes 将 Secret
以 Pod 中一个或多个容器的文件系统中的文件的形式呈现出来。

要配置这种行为，你需要：

<!--
1. Create a secret or use an existing one. Multiple Pods can reference the same secret.
1. Modify your Pod definition to add a volume under `.spec.volumes[]`. Name the volume anything, and have a `.spec.volumes[].secret.secretName` field equal to the name of the Secret object.
1. Add a `.spec.containers[].volumeMounts[]` to each container that needs the secret. Specify `.spec.containers[].volumeMounts[].readOnly = true` and `.spec.containers[].volumeMounts[].mountPath` to an unused directory name where you would like the secrets to appear.
1. Modify your image or command line so that the program looks for files in that directory. Each key in the secret `data` map becomes the filename under `mountPath`.

This is an example of a Pod that mounts a Secret named `mysecret` in a volume:
-->
1. 创建一个 Secret 或者使用已有的 Secret。多个 Pod 可以引用同一个 Secret。
1. 更改 Pod 定义，在 `.spec.volumes[]` 下添加一个卷。根据需要为卷设置其名称，
   并将 `.spec.volumes[].secret.secretName` 字段设置为 Secret 对象的名称。
1. 为每个需要该 Secret 的容器添加 `.spec.containers[].volumeMounts[]`。
   并将 `.spec.containers[].volumeMounts[].readyOnly` 设置为 `true`，
   将 `.spec.containers[].volumeMounts[].mountPath` 设置为希望 Secret
   被放置的、目前尚未被使用的路径名。
1. 更改你的镜像或命令行，以便程序读取所设置的目录下的文件。Secret 的 `data`
   映射中的每个主键都成为 `mountPath` 下面的文件名。

下面是一个通过卷来挂载名为 `mysecret` 的 Secret 的 Pod 示例：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: mypod
    image: redis
    volumeMounts:
    - name: foo
      mountPath: "/etc/foo"
      readOnly: true
  volumes:
  - name: foo
    secret:
      secretName: mysecret
      optional: false # 默认设置，意味着 "mysecret" 必须已经存在
```

<!--
Each Secret you want to use needs to be referred to in `.spec.volumes`.

If there are multiple containers in the Pod, then each container needs its
own `volumeMounts` block, but only one `.spec.volumes` is needed per Secret.
-->
你要访问的每个 Secret 都需要通过 `.spec.volumes` 来引用。

如果 Pod 中包含多个容器，则每个容器需要自己的 `volumeMounts` 块，
不过针对每个 Secret 而言，只需要一份 `.spec.volumes` 设置。

{{< note >}}
<!--
Versions of Kubernetes before v1.22 automatically created credentials for accessing
the Kubernetes API. This older mechanism was based on creating token Secrets that
could then be mounted into running Pods.
In more recent versions, including Kubernetes v{{< skew currentVersion >}}, API credentials
are obtained directly by using the [TokenRequest](/docs/reference/kubernetes-api/authentication-resources/token-request-v1/) API,
and are mounted into Pods using a [projected volume](/docs/reference/access-authn-authz/service-accounts-admin/#bound-service-account-token-volume).
The tokens obtained using this method have bounded lifetimes, and are automatically
invalidated when the Pod they are mounted into is deleted.
-->
Kubernetes v1.22 版本之前都会自动创建用来访问 Kubernetes API 的凭证。
这一老的机制是基于创建可被挂载到 Pod 中的令牌 Secret 来实现的。
在最近的版本中，包括 Kubernetes v{{< skew currentVersion >}} 中，API 凭据是直接通过
[TokenRequest](/docs/reference/kubernetes-api/authentication-resources/token-request-v1/)
API 来获得的，这一凭据会使用[投射卷](/zh/docs/reference/access-authn-authz/service-accounts-admin/#bound-service-account-token-volume)
挂载到 Pod 中。使用这种方式获得的令牌有确定的生命期，并且在挂载它们的 Pod
被删除时自动作废。

<!--
You can still [manually create](/docs/tasks/configure-pod-container/configure-service-account/#manually-create-a-service-account-api-token)
a service account token Secret; for example, if you need a token that never expires.
However, using the [TokenRequest](/docs/reference/kubernetes-api/authentication-resources/token-request-v1/)
subresource to obtain a token to access the API is recommended instead.
-->
你仍然可以[手动创建](/zh/docs/tasks/configure-pod-container/configure-service-account/#manually-create-a-service-account-api-token)
服务账号令牌。例如，当你需要一个永远都不过期的令牌时。
不过，仍然建议使用 [TokenRequest](/docs/reference/kubernetes-api/authentication-resources/token-request-v1/)
子资源来获得访问 API 服务器的令牌。
{{< /note >}}

<!--
#### Projection of Secret keys to specific paths

You can also control the paths within the volume where Secret keys are projected.
You can use the `.spec.volumes[].secret.items` field to change the target path of each key:
-->
#### 将 Secret 键投射到特定目录

你也可以控制 Secret 键所投射到的卷中的路径。
你可以使用 `.spec.volumes[].secret.items` 字段来更改每个主键的目标路径：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: mypod
    image: redis
    volumeMounts:
    - name: foo
      mountPath: "/etc/foo"
      readOnly: true
  volumes:
  - name: foo
    secret:
      secretName: mysecret
      items:
      - key: username
        path: my-group/my-username
```

<!--
What will happen:

* the `username` key from `mysecret` is available to the container at the path
  `/etc/foo/my-group/my-username` instead of at `/etc/foo/username`.
* the `password` key from that Secret object is not projected.

If `.spec.volumes[].secret.items` is used, only keys specified in `items` are projected.
To consume all keys from the Secret, all of them must be listed in the `items` field.

If you list keys explicitly, then all listed keys must exist in the corresponding Secret.
Otherwise, the volume is not created.
-->
将发生的事情如下：

- `mysecret` 中的键 `username` 会出现在容器中的路径为 `/etc/foo/my-group/my-username`，
  而不是 `/etc/foo/username`。
- Secret 对象的 `password` 键不会被投射。

如果使用了 `.spec.volumes[].secret.items`，则只有 `items` 中指定了的主键会被投射。
如果要使用 Secret 中的所有主键，则需要将它们全部枚举到 `items` 字段中。

如果你显式地列举了主键，则所列举的主键都必须在对应的 Secret 中存在。
否则所在的卷不会被创建。

<!--
#### Secret files permissions

You can set the POSIX file access permission bits for a single Secret key.
If you don't specify any permissions, `0644` is used by default.
You can also set a default mode for the entire Secret volume and override per key if needed.

For example, you can specify a default mode like this:
-->
#### Secret 文件的访问权限

你可以为某个 Secret 主键设置 POSIX 文件访问权限位。
如果你不指定访问权限，默认会使用 `0644`。
你也可以为整个 Secret 卷设置默认的访问模式，然后再根据需要在主键层面重载。

例如，你可以像下面这样设置默认的模式：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: mypod
    image: redis
    volumeMounts:
    - name: foo
      mountPath: "/etc/foo"
  volumes:
  - name: foo
    secret:
      secretName: mysecret
      defaultMode: 0400
```

<!--
The secret is mounted on `/etc/foo`; all the files created by the
secret volume mount have permission `0400`.
-->
该 Secret 被挂载在 `/etc/foo` 下，Secret 卷挂载所创建的所有文件的访问模式都是 `0400`。

{{< note >}}
<!--
If you're defining a Pod or a Pod template using JSON, beware that the JSON
specification doesn't support octal notation. You can use the decimal value
for the `defaultMode` (for example, 0400 in octal is 256 in decimal) instead.  
If you're writing YAML, you can write the `defaultMode` in octal.
-->
如果你是使用 JSON 来定义 Pod 或 Pod 模板，需要注意 JSON 规范不支持八进制的记数方式。
你可以在 `defaultMode` 中设置十进制的值（例如，八进制中的 0400 在十进制中为 256）。
如果你使用 YAML 来编写定义，你可以用八进制值来设置 `defaultMode`。
{{< /note >}}

<!--
#### Consuming Secret values from volumes

Inside the container that mounts a secret volume, the secret keys appear as
files. The secret values are base64 decoded and stored inside these files.

This is the result of commands executed inside the container from the example above:
-->
#### 使用来自卷中的 Secret 值  {#consuming-secret-values-from-volumes}

在挂载了 Secret 卷的容器内，Secret 的主键都呈现为文件。
Secret 的取值都是 Base64 编码的，保存在这些文件中。

下面是在上例中的容器内执行命令的结果：

```shell
ls /etc/foo/
```

<!--
The output is similar to:
-->
输出类似于：

```
username
password
```

```shell
cat /etc/foo/username
```

<!--
The output is similar to:
-->
输出类似于：

```
admin
```

```shell
cat /etc/foo/password
```

<!--
The output is similar to:
-->
输出类似于：

```
1f2d1e2e67df
```

<!--
The program in a container is responsible for reading the secret data from these
files, as needed.
-->
容器中的程序要负责根据需要读取 Secret 数据。

<!--
#### Mounted Secrets are updated automatically

When a volume contains data from a Secret, and that Secret is updated, Kubernetes tracks
this and updates the data in the volume, using an eventually-consistent approach.
-->
#### 挂载的 Secret 是被自动更新的  {#mounted-secrets-are-updated-automatically}

当卷中包含来自 Secret 的数据，而对应的 Secret 被更新，Kubernetes
会跟踪到这一操作并更新卷中的数据。更新的方式是保证最终一致性。

{{< note >}}
<!--
A container using a Secret as a
[subPath](/docs/concepts/storage/volumes#using-subpath) volume mount does not receive
automated Secret updates.
-->
对于以 [subPath](/zh/docs/concepts/storage/volumes#using-subpath) 形式挂载 Secret 卷的容器而言，
它们无法收到自动的 Secret 更新。
{{< /note >}}

<!--
The kubelet keeps a cache of the current keys and values for the Secrets that are used in
volumes for pods on that node.
You can configure the way that the kubelet detects changes from the cached values. The `configMapAndSecretChangeDetectionStrategy` field in
the [kubelet configuration](/docs/reference/config-api/kubelet-config.v1beta1/) controls which strategy the kubelet uses. The default strategy is `Watch`.
-->
Kubelet 组件会维护一个缓存，在其中保存节点上 Pod 卷中使用的 Secret 的当前主键和取值。
你可以配置 kubelet 如何检测所缓存数值的变化。
[kubelet 配置](/zh/docs/reference/config-api/kubelet-config.v1beta1/)中的
`configMapAndSecretChangeDetectionStrategy` 字段控制 kubelet 所采用的策略。
默认的策略是 `Watch`。

<!--
Updates to Secrets can be either propagated by an API watch mechanism (the default), based on
a cache with a defined time-to-live, or polled from the cluster API server on each kubelet
synchronisation loop.
-->
对 Secret 的更新操作既可以通过 API 的 watch 机制（默认）来传播，
基于设置了生命期的缓存获取，也可以通过 kubelet 的同步回路来从集群的 API
服务器上轮询获取。

<!--
As a result, the total delay from the moment when the Secret is updated to the moment
when new keys are projected to the Pod can be as long as the kubelet sync period + cache
propagation delay, where the cache propagation delay depends on the chosen cache type
(following the same order listed in the previous paragraph, these are:
watch propagation delay, the configured cache TTL, or zero for direct polling).
-->
因此，从 Secret 被更新到新的主键被投射到 Pod 中，中间存在一个延迟。
这一延迟的上限是 kubelet 的同步周期加上缓存的传播延迟，
其中缓存的传播延迟取决于所选择的缓存类型。
对应上一段中提到的几种传播机制，延迟时长为 watch 的传播延迟、所配置的缓存 TTL
或者对于直接轮询而言是零。

<!--
### Using Secrets as environment variables

To use a Secret in an {{< glossary_tooltip text="environment variable" term_id="container-env-variables" >}}
in a Pod:
-->
### 以环境变量的方式使用 Secret   {#using-secrets-as-environment-variables}

如果需要在 Pod 中以{{< glossary_tooltip text="环境变量" term_id="container-env-variables" >}}
的形式使用 Secret：

<!--
1. Create a Secret (or use an existing one).  Multiple Pods can reference the same Secret.
1. Modify your Pod definition in each container that you wish to consume the value of a secret
   key to add an environment variable for each secret key you wish to consume. The environment
   variable that consumes the secret key should populate the secret's name and key in `env[].valueFrom.secretKeyRef`.
1. Modify your image and/or command line so that the program looks for values in the specified
   environment variables.
-->
1. 创建 Secret（或者使用现有 Secret）。多个 Pod 可以引用同一个 Secret。
1. 更改 Pod 定义，在要使用 Secret 键值的每个容器中添加与所使用的主键对应的环境变量。
   读取 Secret 主键的环境变量应该在 `env[].valueFrom.secretKeyRef` 中填写 Secret
   的名称和主键名称。
1. 更改你的镜像或命令行，以便程序读取环境变量中保存的值。

<!--
This is an example of a Pod that uses a Secret via environment variables:
-->
下面是一个通过环境变量来使用 Secret 的示例 Pod：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: secret-env-pod
spec:
  containers:
  - name: mycontainer
    image: redis
    env:
      - name: SECRET_USERNAME
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: username
            optional: false # 此值为默认值；意味着 "mysecret"
                            # 必须存在且包含名为 "username" 的主键
      - name: SECRET_PASSWORD
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: password
            optional: false # 此值为默认值；意味着 "mysecret"
                            # 必须存在且包含名为 "password" 的主键
  restartPolicy: Never
```

<!--
#### Invalid environment variables {#restriction-env-from-invalid}

Secrets used to populate environment variables by the `envFrom` field that have keys
that are considered invalid environment variable names will have those keys
skipped. The Pod is allowed to start.
-->
#### 非法环境变量    {#restriction-env-from-invalid}

对于通过 `envFrom` 字段来填充环境变量的 Secret 而言，
如果其中包含的主键不能被当做合法的环境变量名，这些主键会被忽略掉。
Pod 仍然可以启动。

<!--
If you define a Pod with an invalid variable name, the failed Pod startup includes
an event with the reason set to `InvalidVariableNames` and a message that lists the
skipped invalid keys. The following example shows a Pod that refers to a Secret
named `mysecret`, where `mysecret` contains 2 invalid keys: `1badkey` and `2alsobad`.
-->
如果你定义的 Pod 中包含非法的变量名称，则 Pod 可能启动失败，
会形成 reason 为 `InvalidVariableNames` 的事件，以及列举被略过的非法主键的消息。
下面的例子中展示了一个 Pod，引用的是名为 `mysecret` 的 Secret，
其中包含两个非法的主键：`1badkey` 和 `2alsobad`。

```shell
kubectl get events
```

<!--
The output is similar to:
-->
输出类似于：

```
LASTSEEN   FIRSTSEEN   COUNT     NAME            KIND      SUBOBJECT                         TYPE      REASON
0s         0s          1         dapi-test-pod   Pod                                         Warning   InvalidEnvironmentVariableNames   kubelet, 127.0.0.1      Keys [1badkey, 2alsobad] from the EnvFrom secret default/mysecret were skipped since they are considered invalid environment variable names.
```

<!--
#### Consuming Secret values from environment variables

Inside a container that consumes a Secret using environment variables, the secret keys appear
as normal environment variables. The values of those variables are the base64 decoded values
of the secret data.

This is the result of commands executed inside the container from the example above:
-->
#### 通过环境变量使用 Secret 值

在通过环境变量来使用 Secret 的容器中，Secret 主键展现为普通的环境变量。
这些变量的取值是 Secret 数据的 Base64 解码值。

下面是在前文示例中的容器内执行命令的结果：

```shell
echo "$SECRET_USERNAME"
```

<!--
The output is similar to:
-->
输出类似于：

```
admin
```

```shell
echo "$SECRET_PASSWORD"
```

<!--
The output is similar to:
-->
输出类似于：

```
1f2d1e2e67df
```

{{< note >}}
<!--
If a container already consumes a Secret in an environment variable,
a Secret update will not be seen by the container unless it is
restarted. There are third party solutions for triggering restarts when
secrets change.
-->
如果容器已经在通过环境变量来使用 Secret，Secret 更新在容器内是看不到的，
除非容器被重启。有一些第三方的解决方案，能够在 Secret 发生变化时触发容器重启。
{{< /note >}}

<!--
### Container image pull secrets {#using-imagepullsecrets}

If you want to fetch container images from a private repository, you need a way for
the kubelet on each node to authenticate to that repository. You can configure
_image pull secrets_ to make this possible. These secrets are configured at the Pod
level.
-->
### 容器镜像拉取 Secret  {#using-imagepullsecrets}

如果你尝试从私有仓库拉取容器镜像，你需要一种方式让每个节点上的 kubelet
能够完成与镜像库的身份认证。你可以配置 *镜像拉取 Secret* 来实现这点。
Secret 是在 Pod 层面来配置的。

<!--
The `imagePullSecrets` field for a Pod is a list of references to Secrets in the same namespace
as the Pod.
You can use an `imagePullSecrets` to pass image registry access credentials to
the kubelet. The kubelet uses this information to pull a private image on behalf of your Pod.
See `PodSpec` in the [Pod API reference](/docs/reference/kubernetes-api/workload-resources/pod-v1/#PodSpec)
for more information about the `imagePullSecrets` field.
-->
Pod 的 `imagePullSecrets` 字段是一个对 Pod 所在的名字空间中的 Secret
的引用列表。你可以使用 `imagePullSecrets` 来将镜像仓库访问凭据传递给 kubelet。
kubelet 使用这个信息来替你的 Pod 拉取私有镜像。
参阅 [Pod API 参考](/docs/reference/kubernetes-api/workload-resources/pod-v1/#PodSpec)
中的 `PodSpec` 进一步了解 `imagePullSecrets` 字段。

<!--
#### Using imagePullSecrets

The `imagePullSecrets` field is a list of references to secrets in the same namespace.
You can use an `imagePullSecrets` to pass a secret that contains a Docker (or other) image registry
password to the kubelet. The kubelet uses this information to pull a private image on behalf of your Pod.
See the [PodSpec API](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#podspec-v1-core) for more information about the `imagePullSecrets` field.
-->
#### 使用 imagePullSecrets

`imagePullSecrets` 字段是一个列表，包含对同一名字空间中 Secret 的引用。
你可以使用 `imagePullSecrets` 将包含 Docker（或其他）镜像仓库密码的 Secret
传递给 kubelet。kubelet 使用此信息来替 Pod 拉取私有镜像。
参阅 [PodSpec API ](/docs/reference/kubernetes-api/workload-resources/pod-v1/#PodSpec)
进一步了解 `imagePullSecrets` 字段。

<!--
##### Manually specifying an imagePullSecret

You can learn how to specify `imagePullSecrets` from the [container images](/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod)
documentation.
-->
##### 手动设定 imagePullSecret

你可以通过阅读[容器镜像](/zh/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod)
文档了解如何设置 `imagePullSecrets`。

<!--
##### Arranging for imagePullSecrets to be automatically attached

You can manually create `imagePullSecrets`, and reference these from
a ServiceAccount. Any Pods created with that ServiceAccount
or created with that ServiceAccount by default, will get their `imagePullSecrets`
field set to that of the service account.
See [Add ImagePullSecrets to a service account](/docs/tasks/configure-pod-container/configure-service-account/#add-imagepullsecrets-to-a-service-account)
 for a detailed explanation of that process.
-->
##### 设置 imagePullSecrets 为自动挂载

你可以手动创建 `imagePullSecret`，并在一个 ServiceAccount 中引用它。
对使用该 ServiceAccount 创建的所有 Pod，或者默认使用该 ServiceAccount 创建的 Pod
而言，其 `imagePullSecrets` 字段都会设置为该服务账号。
请阅读[向服务账号添加 ImagePullSecrets](/zh/docs/tasks/configure-pod-container/configure-service-account/#add-imagepullsecrets-to-a-service-account)
来详细了解这一过程。

<!--
### Using Secrets with static Pods {#restriction-static-pod}

You cannot use ConfigMaps or Secrets with
{{< glossary_tooltip text="static Pods" term_id="static-pod" >}}.
-->
### 在静态 Pod 中使用 Secret    {#restriction-static-pod}

你不可以在{{< glossary_tooltip text="静态 Pod" term_id="static-pod" >}}.
中使用 ConfigMap 或 Secret。

<!--
## Use cases

### Use case: As container environment variables

Create a secret
-->
## 使用场景  {#use-case}

### 使用场景：作为容器环境变量

创建 Secret：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  USER_NAME: YWRtaW4=
  PASSWORD: MWYyZDFlMmU2N2Rm
```

<!--
Create the Secret:
-->
创建 Secret：

```shell
kubectl apply -f mysecret.yaml
```

<!--
Use `envFrom` to define all of the Secret's data as container environment variables. The key from the Secret becomes the environment variable name in the Pod.
-->
使用 `envFrom` 来将 Secret 的所有数据定义为容器的环境变量。
来自 Secret 的主键成为 Pod 中的环境变量名称：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: secret-test-pod
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
      command: [ "/bin/sh", "-c", "env" ]
      envFrom:
      - secretRef:
          name: mysecret
  restartPolicy: Never
```

<!--
### Use case: Pod with SSH keys

Create a Secret containing some SSH keys:
-->
### 使用场景：带 SSH 密钥的 Pod

创建包含一些 SSH 密钥的 Secret：

```shell
kubectl create secret generic ssh-key-secret --from-file=ssh-privatekey=/path/to/.ssh/id_rsa --from-file=ssh-publickey=/path/to/.ssh/id_rsa.pub
```

<!--
The output is similar to:
-->
输出类似于：

```
secret "ssh-key-secret" created
```

<!--
You can also create a `kustomization.yaml` with a `secretGenerator` field containing ssh keys.
-->
你也可以创建一个 `kustomization.yaml` 文件，在其 `secretGenerator`
字段中包含 SSH 密钥。

{{< caution >}}
<!--
Think carefully before sending your own SSH keys: other users of the cluster may have access
to the Secret.
-->
在提供你自己的 SSH 密钥之前要仔细思考：集群的其他用户可能有权访问该 Secret。

<!--
You could instead create an SSH private key representing a service identity that you want to be
accessible to all the users with whom you share the Kubernetes cluster, and that you can revoke
if the credentials are compromised.
-->
你也可以创建一个 SSH 私钥，代表一个你希望与你共享 Kubernetes 集群的其他用户分享的服务标识。
当凭据信息被泄露时，你可以收回该访问权限。
{{< /caution >}}

<!--
Now you can create a Pod which references the secret with the SSH key and
consumes it in a volume:
-->
现在你可以创建一个 Pod，在其中访问包含 SSH 密钥的 Secret，并通过卷的方式来使用它：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: secret-test-pod
  labels:
    name: secret-test
spec:
  volumes:
  - name: secret-volume
    secret:
      secretName: ssh-key-secret
  containers:
  - name: ssh-test-container
    image: mySshImage
    volumeMounts:
    - name: secret-volume
      readOnly: true
      mountPath: "/etc/secret-volume"
```

<!--
When the container's command runs, the pieces of the key will be available in:
-->
容器命令执行时，秘钥的数据可以在下面的位置访问到：

```
/etc/secret-volume/ssh-publickey
/etc/secret-volume/ssh-privatekey
```

<!--
The container is then free to use the secret data to establish an SSH connection.
-->
容器就可以随便使用 Secret 数据来建立 SSH 连接。

<!--
### Use case: Pods with prod / test credentials

This example illustrates a Pod which consumes a secret containing production
credentials and another Pod which consumes a secret with test environment
credentials.

You can create a `kustomization.yaml` with a `secretGenerator` field or run
`kubectl create secret`.
-->
### 使用场景：带有生产、测试环境凭据的 Pod

这一示例所展示的一个 Pod 会使用包含生产环境凭据的 Secret，另一个 Pod
使用包含测试环境凭据的 Secret。

你可以创建一个带有 `secretGenerator` 字段的 `kustomization.yaml` 文件或者运行
`kubectl create secret` 来创建 Secret。

```shell
kubectl create secret generic prod-db-secret --from-literal=username=produser --from-literal=password=Y4nys7f11
```

<!--
The output is similar to:
-->
输出类似于：

```
secret "prod-db-secret" created
```

<!--
You can also create a secret for test environment credentials.
-->
你也可以创建一个包含测试环境凭据的 Secret：

```shell
kubectl create secret generic test-db-secret --from-literal=username=testuser --from-literal=password=iluvtests
```

<!--
The output is similar to:
-->
输出类似于：

```
secret "test-db-secret" created
```

{{< note >}}
<!--
Special characters such as `$`, `\`, `*`, `=`, and `!` will be interpreted by your [shell](https://en.wikipedia.org/wiki/Shell_(computing)) and require escaping.
-->
特殊字符（例如 `$`、`\`、`*`、`=` 和 `!`）会被你的
[Shell](https://en.wikipedia.org/wiki/Shell_(computing))解释，因此需要转义。

<!--
In most shells, the easiest way to escape the password is to surround it with single quotes (`'`).
For example, if your actual password is `S!B\*d$zDsb=`, you should execute the command this way:
-->
在大多数 Shell 中，对密码进行转义的最简单方式是用单引号（`'`）将其括起来。
例如，如果你的实际密码是 `S!B\*d$zDsb`，则应通过以下方式执行命令：

```shell
kubectl create secret generic dev-db-secret --from-literal=username=devuser --from-literal=password='S!B\*d$zDsb='
```
<!--
You do not need to escape special characters in passwords from files (`--from-file`).
-->
你无需对文件中的密码（`--from-file`）中的特殊字符进行转义。
{{< /note >}}

<!--
Now make the Pods:
-->
现在生成 Pod：

```shell
cat <<EOF > pod.yaml
apiVersion: v1
kind: List
items:
- kind: Pod
  apiVersion: v1
  metadata:
    name: prod-db-client-pod
    labels:
      name: prod-db-client
  spec:
    volumes:
    - name: secret-volume
      secret:
        secretName: prod-db-secret
    containers:
    - name: db-client-container
      image: myClientImage
      volumeMounts:
      - name: secret-volume
        readOnly: true
        mountPath: "/etc/secret-volume"
- kind: Pod
  apiVersion: v1
  metadata:
    name: test-db-client-pod
    labels:
      name: test-db-client
  spec:
    volumes:
    - name: secret-volume
      secret:
        secretName: test-db-secret
    containers:
    - name: db-client-container
      image: myClientImage
      volumeMounts:
      - name: secret-volume
        readOnly: true
        mountPath: "/etc/secret-volume"
EOF
```

<!--
Add the pods to the same `kustomization.yaml`:
-->
将 Pod 添加到同一 `kustomization.yaml` 文件中：

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

<!--
Apply all those objects on the API server by running:
-->
通过下面的命令在 API 服务器上应用所有这些对象：

```shell
kubectl apply -k .
```

<!--
Both containers will have the following files present on their filesystems with the values
for each container's environment:
-->
两个文件都会在其文件系统中出现下面面的文件，文件中内容是各个容器的环境值：

```
/etc/secret-volume/username
/etc/secret-volume/password
```

<!--
Note how the specs for the two Pods differ only in one field; this facilitates
creating Pods with different capabilities from a common Pod template.
-->
注意这两个 Pod 的规约中只有一个字段不同。
这便于基于相同的 Pod 模板生成具有不同能力的 Pod。

<!--
You could further simplify the base Pod specification by using two service accounts:

1. `prod-user` with the `prod-db-secret`
1. `test-user` with the `test-db-secret`

The Pod specification is shortened to:
-->
你可以通过使用两个服务账号来进一步简化这一基本的 Pod 规约：

1. `prod-user` 服务账号使用 `prod-db-secret`
1. `test-user` 服务账号使用 `test-db-secret`

Pod 规约简化为：

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: prod-db-client-pod
  labels:
    name: prod-db-client
spec:
  serviceAccount: prod-db-client
  containers:
  - name: db-client-container
    image: myClientImage
```

<!--
### Use case: dotfiles in a secret volume

You can make your data "hidden" by defining a key that begins with a dot.
This key represents a dotfile or "hidden" file. For example, when the following secret
is mounted into a volume, `secret-volume`:
-->
### 使用场景：在 Secret 卷中带句点的文件

通过定义以句点（`.`）开头的主键，你可以“隐藏”你的数据。
这些主键代表的是以句点开头的文件或“隐藏”文件。
例如，当下面的 Secret 被挂载到 `secret-volume` 卷中时：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: dotfile-secret
data:
  .secret-file: dmFsdWUtMg0KDQo=
---
apiVersion: v1
kind: Pod
metadata:
  name: secret-dotfiles-pod
spec:
  volumes:
  - name: secret-volume
    secret:
      secretName: dotfile-secret
  containers:
  - name: dotfile-test-container
    image: k8s.gcr.io/busybox
    command:
    - ls
    - "-l"
    - "/etc/secret-volume"
    volumeMounts:
    - name: secret-volume
      readOnly: true
      mountPath: "/etc/secret-volume"
```

<!--
The volume will contain a single file, called `.secret-file`, and
the `dotfile-test-container` will have this file present at the path
`/etc/secret-volume/.secret-file`.
-->
卷中会包含一个名为 `.secret-file` 的文件，并且容器 `dotfile-test-container`
中此文件位于路径 `/etc/secret-volume/.secret-file` 处。

{{< note >}}
<!--
Files beginning with dot characters are hidden from the output of  `ls -l`;
you must use `ls -la` to see them when listing directory contents.
-->
以句点开头的文件会在 `ls -l` 的输出中被隐藏起来；
列举目录内容时你必须使用 `ls -la` 才能看到它们。
{{< /note >}}

<!--
### Use case: Secret visible to one container in a Pod

Consider a program that needs to handle HTTP requests, do some complex business
logic, and then sign some messages with an HMAC. Because it has complex
application logic, there might be an unnoticed remote file reading exploit in
the server, which could expose the private key to an attacker.
-->
### 使用场景：仅对 Pod 中一个容器可见的 Secret

考虑一个需要处理 HTTP 请求，执行某些复杂的业务逻辑，之后使用 HMAC
来对某些消息进行签名的程序。因为这一程序的应用逻辑很复杂，
其中可能包含未被注意到的远程服务器文件读取漏洞，
这种漏洞可能会把私钥暴露给攻击者。

<!--
This could be divided into two processes in two containers: a frontend container
which handles user interaction and business logic, but which cannot see the
private key; and a signer container that can see the private key, and responds
to simple signing requests from the frontend (for example, over localhost networking).
-->
这一程序可以分隔成两个容器中的两个进程：前端容器要处理用户交互和业务逻辑，
但无法看到私钥；签名容器可以看到私钥，并对来自前端的简单签名请求作出响应
（例如，通过本地主机网络）。

<!--
With this partitioned approach, an attacker now has to trick the application
server into doing something rather arbitrary, which may be harder than getting
it to read a file.
-->
采用这种划分的方法，攻击者现在必须欺骗应用服务器来做一些其他操作，
而这些操作可能要比读取一个文件要复杂很多。

<!--
## Types of Secret {#secret-types}

When creating a Secret, you can specify its type using the `type` field of
the [Secret](/docs/reference/kubernetes-api/config-and-storage-resources/secret-v1/)
resource, or certain equivalent `kubectl` command line flags (if available).
The Secret type is used to facilitate programmatic handling of the Secret data.

Kubernetes provides several builtin types for some common usage scenarios.
These types vary in terms of the validations performed and the constraints
Kubernetes imposes on them.
-->
## Secret 的类型  {#secret-types}

创建 Secret 时，你可以使用 [Secret](/docs/reference/kubernetes-api/config-and-storage-resources/secret-v1/)
资源的 `type` 字段，或者与其等价的 `kubectl` 命令行参数（如果有的话）为其设置类型。
Secret 类型有助于对 Secret 数据进行编程处理。

Kubernetes 提供若干种内置的类型，用于一些常见的使用场景。
针对这些类型，Kubernetes 所执行的合法性检查操作以及对其所实施的限制各不相同。

<!--
| Builtin Type | Usage |
|--------------|-------|
| `Opaque`     |  arbitrary user-defined data |
| `kubernetes.io/service-account-token` | service account token |
| `kubernetes.io/dockercfg` | serialized `~/.dockercfg` file |
| `kubernetes.io/dockerconfigjson` | serialized `~/.docker/config.json` file |
| `kubernetes.io/basic-auth` | credentials for basic authentication |
| `kubernetes.io/ssh-auth` | credentials for SSH authentication |
| `kubernetes.io/tls` | data for a TLS client or server |
| `bootstrap.kubernetes.io/token` | bootstrap token data |
-->
| 内置类型     | 用法  |
|--------------|-------|
| `Opaque`     | 用户定义的任意数据 |
| `kubernetes.io/service-account-token` | 服务账号令牌 |
| `kubernetes.io/dockercfg` | `~/.dockercfg` 文件的序列化形式 |
| `kubernetes.io/dockerconfigjson` | `~/.docker/config.json` 文件的序列化形式 |
| `kubernetes.io/basic-auth` | 用于基本身份认证的凭据 |
| `kubernetes.io/ssh-auth` | 用于 SSH 身份认证的凭据 |
| `kubernetes.io/tls` | 用于 TLS 客户端或者服务器端的数据 |
| `bootstrap.kubernetes.io/token` | 启动引导令牌数据 |

<!--
You can define and use your own Secret type by assigning a non-empty string as the
`type` value for a Secret object. An empty string is treated as an `Opaque` type.
-->
通过为 Secret 对象的 `type` 字段设置一个非空的字符串值，你也可以定义并使用自己
Secret 类型。如果 `type` 值为空字符串，则被视为 `Opaque` 类型。

<!--
Kubernetes doesn't impose any constraints on the type name. However, if you
are using one of the builtin types, you must meet all the requirements defined
for that type.
-->
Kubernetes 并不对类型的名称作任何限制。不过，如果你要使用内置类型之一，
则你必须满足为该类型所定义的所有要求。

<!--
If you are defining a type of secret that's for public use, follow the convention
and structure the secret type to have your domain name before the name, separated
by a `/`. For example: `cloud-hosting.example.net/cloud-api-credentials`.
-->
如果你要定义一种公开使用的 Secret 类型，请遵守 Secret 类型的约定和结构，
在类型名签名添加域名，并用 `/` 隔开。
例如：`cloud-hosting.example.net/cloud-api-credentials`。

<!--
### Opaque secrets

`Opaque` is the default Secret type if omitted from a Secret configuration file.
When you create a Secret using `kubectl`, you will use the `generic`
subcommand to indicate an `Opaque` Secret type. For example, the following
command creates an empty Secret of type `Opaque`.
-->
### Opaque Secret

当 Secret 配置文件中未作显式设定时，默认的 Secret 类型是 `Opaque`。
当你使用 `kubectl` 来创建一个 Secret 时，你会使用 `generic` 子命令来标明
要创建的是一个 `Opaque` 类型 Secret。
例如，下面的命令会创建一个空的 `Opaque` 类型 Secret 对象：

```shell
kubectl create secret generic empty-secret
kubectl get secret empty-secret
```

<!--
The output looks like:
-->
输出类似于

```
NAME           TYPE     DATA   AGE
empty-secret   Opaque   0      2m6s
```

<!--
The `DATA` column shows the number of data items stored in the Secret.
In this case, `0` means we have created an empty Secret.
-->
`DATA` 列显示 Secret 中保存的数据条目个数。
在这个例子种，`0` 意味着我们刚刚创建了一个空的 Secret。

<!--
###  Service account token Secrets

A `kubernetes.io/service-account-token` type of Secret is used to store a
token that identifies a
{{< glossary_tooltip text="service account" term_id="service-account" >}}.
When using this Secret type, you need to ensure that the
`kubernetes.io/service-account.name` annotation is set to an existing
service account name. A Kubernetes
{{< glossary_tooltip text="controller" term_id="controller" >}} fills in some
other fields such as the `kubernetes.io/service-account.uid` annotation and the
`token` key in the `data` field, which is  set to contain an authentication
token.

The following example configuration declares a service account token Secret:
-->
### 服务账号令牌 Secret  {#service-account-token-secrets}

类型为 `kubernetes.io/service-account-token` 的 Secret 用来存放标识某
{{< glossary_tooltip text="服务账号" term_id="service-account" >}}的令牌。
使用这种 Secret 类型时，你需要确保对象的注解 `kubernetes.io/service-account-name`
被设置为某个已有的服务账号名称。某个 Kubernetes
{{< glossary_tooltip text="控制器" term_id="controller" >}}会填写 Secret
的其它字段，例如 `kubernetes.io/service-account.uid` 注解以及 `data` 字段中的
`token` 键值，使之包含实际的令牌内容。

下面的配置实例声明了一个服务账号令牌 Secret：

<!--
```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-sa-sample
  annotations:
    kubernetes.io/service-account.name: "sa-name"
type: kubernetes.io/service-account-token
data:
  # You can include additional key value pairs as you do with Opaque Secrets
  extra: YmFyCg==
```
-->
```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-sa-sample
  annotations:
    kubernetes.io/service-account.name: "sa-name"
type: kubernetes.io/service-account-token
data:
  # 你可以像 Opaque Secret 一样在这里添加额外的键/值偶对
  extra: YmFyCg==
```

<!--
When creating a `Pod`, Kubernetes automatically creates a service account
Secret and automatically modifies your Pod to use this Secret. The service account
token Secret contains credentials for accessing the API.

The automatic creation and use of API credentials can be disabled or
overridden if desired. However, if all you need to do is securely access the
API server, this is the recommended workflow.
-->
Kubernetes 在创建 Pod 时会自动创建一个服务账号 Secret 并自动修改你的 Pod
以使用该 Secret。该服务账号令牌 Secret 中包含了访问 Kubernetes API
所需要的凭据。

如果需要，可以禁止或者重载这种自动创建并使用 API 凭据的操作。
不过，如果你仅仅是希望能够安全地访问 API 服务器，这是建议的工作方式。

<!--
See the [ServiceAccount](/docs/tasks/configure-pod-container/configure-service-account/)
documentation for more information on how service accounts work.
You can also check the `automountServiceAccountToken` field and the
`serviceAccountName` field of the
[`Pod`](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#secret-v1-core)
for information on referencing service account from Pods.
-->
参考 [ServiceAccount](/zh/docs/tasks/configure-pod-container/configure-service-account/)
文档了解服务账号的工作原理。你也可以查看
[`Pod`](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#pod-v1-core)
资源中的 `automountServiceAccountToken` 和 `serviceAccountName` 字段文档，
进一步了解从 Pod 中引用服务账号。

<!--
### Docker config Secrets

You can use one of the following `type` values to create a Secret to
store the credentials for accessing a Docker registry for images.
-->
### Docker 配置 Secret  {#docker-config-secrets}

你可以使用下面两种 `type` 值之一来创建 Secret，用以存放访问 Docker 仓库
来下载镜像的凭据。

- `kubernetes.io/dockercfg`
- `kubernetes.io/dockerconfigjson`

<!--
The `kubernetes.io/dockercfg` type is reserved to store a serialized
`~/.dockercfg` which is the legacy format for configuring Docker command line.
When using this Secret type, you have to ensure the Secret `data` field
contains a `.dockercfg` key whose value is content of a `~/.dockercfg` file
encoded in the base64 format.
-->
`kubernetes.io/dockercfg` 是一种保留类型，用来存放 `~/.dockercfg` 文件的序列化形式。
该文件是配置 Docker 命令行的一种老旧形式。使用此 Secret 类型时，你需要确保
Secret 的 `data` 字段中包含名为 `.dockercfg` 的主键，其对应键值是用 base64
编码的某 `~/.dockercfg` 文件的内容。

<!--
The `kubernetes/dockerconfigjson` type is designed for storing a serialized
JSON that follows the same format rules as the `~/.docker/config.json` file
which is a new format for `~/.dockercfg`.
When using this Secret type, the `data` field of the Secret object must
contain a `.dockerconfigjson` key, in which the content for the
`~/.docker/config.json` file is provided as a base64 encoded string.

Below is an example for a `kubernetes.io/dockercfg` type of Secret:
-->
类型 `kubernetes.io/dockerconfigjson` 被设计用来保存 JSON 数据的序列化形式，
该 JSON 也遵从 `~/.docker/config.json` 文件的格式规则，而后者是 `~/.dockercfg`
的新版本格式。使用此 Secret 类型时，Secret 对象的 `data` 字段必须包含
`.dockerconfigjson` 键，其键值为 base64 编码的字符串包含 `~/.docker/config.json`
文件的内容。

下面是一个 `kubernetes.io/dockercfg` 类型 Secret 的示例：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-dockercfg
type: kubernetes.io/dockercfg
data:
  .dockercfg: |
    "<base64 encoded ~/.dockercfg file>"
```

{{< note >}}
<!--
If you do not want to perform the base64 encoding, you can choose to use the
`stringData` field instead.
-->
如果你不希望执行 base64 编码转换，可以使用 `stringData` 字段代替。
{{< /note >}}

<!--
When you create these types of Secrets using a manifest, the API
server checks whether the expected key does exists in the `data` field, and
it verifies if the value provided can be parsed as a valid JSON. The API
server doesn't validate if the JSON actually is a Docker config file.

When you do not have a Docker config file, or you want to use `kubectl`
to create a Docker registry Secret, you can do:
-->
当你使用清单文件来创建这两类 Secret 时，API 服务器会检查 `data` 字段中是否
存在所期望的主键，并且验证其中所提供的键值是否是合法的 JSON 数据。
不过，API 服务器不会检查 JSON 数据本身是否是一个合法的 Docker 配置文件内容。

```shell
kubectl create secret docker-registry secret-tiger-docker \
  --docker-email=tiger@acme.example \
  --docker-username=tiger \
  --docker-password=pass113 \
  --docker-server=my-registry.example:5000
```

<!--
This command creates a Secret of type `kubernetes.io/dockerconfigjson`.
If you dump the `.data.dockerconfigjson` field from the new Secret and then
decode it from base64:
-->
上面的命令创建一个类型为 `kubernetes.io/dockerconfigjson` 的 Secret。
如果你对 `.data.dockerconfigjson` 内容进行转储并执行 base64 解码：

```json
{
  "auths": {
    "my-registry.example:5000": {
      "username": "tiger",
      "password": "pass113",
      "email": "tiger@acme.com",
      "auth": "dGlnZXI6cGFzczExMw=="
    }
  }
}
```

{{< note >}}
<!--
The `auth` value there is base64 encoded; it is obscured but not secret.
Anyone who can read that Secret can learn the registry access bearer token.
-->
`auths` 值是 base64 编码的，其内容被屏蔽但未被加密。
任何能够读取该 Secret 的人都可以了解镜像库的访问令牌。
{{< /note >}}

<!--
### Basic authentication Secret

The `kubernetes.io/basic-auth` type is provided for storing credentials needed
for basic authentication. When using this Secret type, the `data` field of the
Secret must contain the following two keys:

- `username`: the user name for authentication;
- `password`: the password or token for authentication.
-->
### 基本身份认证 Secret  {#basic-authentication-secret}

`kubernetes.io/basic-auth` 类型用来存放用于基本身份认证所需的凭据信息。
使用这种 Secret 类型时，Secret 的 `data` 字段必须包含以下两个键：

- `username`: 用于身份认证的用户名；
- `password`: 用于身份认证的密码或令牌。

<!--
Both values for the above two keys are base64 encoded strings. You can, of
course, provide the clear text content using the `stringData` for Secret
creation.

The following YAML is an example config for a basic authentication Secret:
-->
以上两个键的键值都是 base64 编码的字符串。
当然你也可以在创建 Secret 时使用 `stringData` 字段来提供明文形式的内容。
下面的 YAML 是基本身份认证 Secret 的一个示例清单：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-basic-auth
type: kubernetes.io/basic-auth
stringData:
  username: admin      #  kubernetes.io/basic-auth 类型的必需字段
  password: t0p-Secret # kubernetes.io/basic-auth 类型的必需字段
```

<!--
The basic authentication Secret type is provided only for convenience.
You can create an `Opaque` for credentials used for basic authentication.
However, using the defined and public Secret type (`kubernetes.io/basic-auth`) helps other
people to understand the purpose of your Secret, and sets a convention for what key names
to expect.
The Kubernetes API verifies that the required keys are set for a Secret
of this type.
-->
提供基本身份认证类型的 Secret 仅仅是出于方便性考虑。
你也可以使用 `Opaque` 类型来保存用于基本身份认证的凭据。
不过，使用预定义的、公开的 Secret 类型（`kubernetes.io/basic-auth`）
有助于帮助其他用户理解 Secret 的目的，并且对其中存在的主键形成一种约定。
API 服务器会检查 Secret 配置中是否提供了所需要的主键。

<!--
### SSH authentication secrets

The builtin type `kubernetes.io/ssh-auth` is provided for storing data used in
SSH authentication. When using this Secret type, you will have to specify a
`ssh-privatekey` key-value pair in the `data` (or `stringData`) field.
as the SSH credential to use.

The following manifest is an example of a Secret used for SSH public/private
key authentication:
-->
### SSH 身份认证 Secret {#ssh-authentication-secrets}

Kubernetes 所提供的内置类型 `kubernetes.io/ssh-auth` 用来存放 SSH 身份认证中
所需要的凭据。使用这种 Secret 类型时，你就必须在其 `data` （或 `stringData`）
字段中提供一个 `ssh-privatekey` 键值对，作为要使用的 SSH 凭据。

下面的清单是一个 SSH 公钥/私钥身份认证的 Secret 示例：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-ssh-auth
type: kubernetes.io/ssh-auth
data:
  # 此例中的实际数据被截断
  ssh-privatekey: |
     MIIEpQIBAAKCAQEAulqb/Y ...
```

<!--
The SSH authentication Secret type is provided only for user's convenience.
You could instead create an `Opaque` type Secret for credentials used for SSH authentication.
However, using the defined and public Secret type (`kubernetes.io/ssh-auth`) helps other
people to understand the purpose of your Secret, and sets a convention for what key names
to expect.
and the API server does verify if the required keys are provided in a Secret
configuration.
-->
提供 SSH 身份认证类型的 Secret 仅仅是出于用户方便性考虑。
你也可以使用 `Opaque` 类型来保存用于 SSH 身份认证的凭据。
不过，使用预定义的、公开的 Secret 类型（`kubernetes.io/ssh-auth`）
有助于其他人理解你的 Secret 的用途，也可以就其中包含的主键名形成约定。
API 服务器确实会检查 Secret 配置中是否提供了所需要的主键。

{{< caution >}}
<!--
SSH private keys do not establish trusted communication between an SSH client and
host server on their own. A secondary means of establishing trust is needed to
mitigate "man in the middle" attacks, such as a `known_hosts` file added to a
ConfigMap.
-->
SSH 私钥自身无法建立 SSH 客户端与服务器端之间的可信连接。
需要其它方式来建立这种信任关系，以缓解“中间人（Man In The Middle）”
攻击，例如向 ConfigMap 中添加一个 `known_hosts` 文件。
{{< /caution >}}

<!--
### TLS secrets

Kubernetes provides a builtin Secret type `kubernetes.io/tls` for storing
a certificate and its associated key that are typically used for TLS.

One common use for TLS secrets is to configure encryption in transit for
an [Ingress](/docs/concepts/services-networking/ingress/), but you can also use it
with other resources or directly in your workload.
When using this type of Secret, the `tls.key` and the `tls.crt` key must be provided
in the `data` (or `stringData`) field of the Secret configuration, although the API
server doesn't actually validate the values for each key.

The following YAML contains an example config for a TLS Secret:
-->
### TLS Secret

Kubernetes 提供一种内置的 `kubernetes.io/tls` Secret 类型，用来存放 TLS
场合通常要使用的证书及其相关密钥。
TLS Secret 的一种典型用法是为 [Ingress](/zh/docs/concepts/services-networking/ingress/)
资源配置传输过程中的数据加密，不过也可以用于其他资源或者直接在负载中使用。
当使用此类型的 Secret 时，Secret 配置中的 `data` （或 `stringData`）字段必须包含
`tls.key` 和 `tls.crt` 主键，尽管 API 服务器实际上并不会对每个键的取值作进一步的合法性检查。

下面的 YAML 包含一个 TLS Secret 的配置示例：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: secret-tls
type: kubernetes.io/tls
data:
  # 此例中的数据被截断
  tls.crt: |
    MIIC2DCCAcCgAwIBAgIBATANBgkqh ...
  tls.key: |
    MIIEpgIBAAKCAQEA7yn3bRHQ5FHMQ ...
```

<!--
The TLS Secret type is provided for user's convenience. You can create an `Opaque`
for credentials used for TLS server and/or client. However, using the builtin Secret
type helps ensure the consistency of Secret format in your project; the API server
does verify if the required keys are provided in a Secret configuration.

When creating a TLS Secret using `kubectl`, you can use the `tls` subcommand
as shown in the following example:
-->
提供 TLS 类型的 Secret 仅仅是出于用户方便性考虑。
你也可以使用 `Opaque` 类型来保存用于 TLS 服务器与/或客户端的凭据。
不过，使用内置的 Secret 类型的有助于对凭据格式进行归一化处理，并且
API 服务器确实会检查 Secret 配置中是否提供了所需要的主键。

当使用 `kubectl` 来创建 TLS Secret 时，你可以像下面的例子一样使用 `tls`
子命令：

```shell
kubectl create secret tls my-tls-secret \
  --cert=path/to/cert/file \
  --key=path/to/key/file
```

<!--
The public/private key pair must exist beforehand. The public key certificate
for `--cert` must be DER format as per
[Section 5.1 of RFC 7468](https://datatracker.ietf.org/doc/html/rfc7468#section-5.1),
and must match the given private key for `--key` (PKCS #8 in DER format;
[Section 11 of RFC 7468](https://datatracker.ietf.org/doc/html/rfc7468#section-11)).
-->
这里的公钥/私钥对都必须事先已存在。用于 `--cert` 的公钥证书必须是
[RFC 7468 中 5.1 节](https://datatracker.ietf.org/doc/html/rfc7468#section-5.1)
中所规定的 DER 格式，且与 `--key` 所给定的私钥匹配。
私钥必须是 DER 格式的 PKCS #8
（参见 [RFC 7468 第 11节](https://datatracker.ietf.org/doc/html/rfc7468#section-11)）。

{{< note >}}
<!--
A kubernetes.io/tls Secret stores the Base64-encoded DER data for keys and
certificates. If you're familiar with PEM format for private keys and for certificates,
the base64 data are the same as that format except that you omit
the initial and the last lines that are used in PEM.
-->
类型为 `kubernetes.io/tls` 的 Secret 中包含密钥和证书的 DER 数据，以 Base64 格式编码。
如果你熟悉私钥和证书的 PEM 格式，base64 与该格式相同，只是你需要略过 PEM
数据中所包含的第一行和最后一行。

<!--
For example, for a certificate, you do **not** include `--------BEGIN CERTIFICATE-----`
and `-------END CERTIFICATE----`.
-->
例如，对于证书而言，你 **不要** 包含 `--------BEGIN CERTIFICATE-----`
和 `-------END CERTIFICATE----` 这两行。
{{< /note >}}

<!--
### Bootstrap token Secrets

A bootstrap token Secret can be created by explicitly specifying the Secret
`type` to `bootstrap.kubernetes.io/token`. This type of Secret is designed for
tokens used during the node bootstrap process. It stores tokens used to sign
well known ConfigMaps.
-->
### 启动引导令牌 Secret  {#bootstrap-token-secrets}

通过将 Secret 的 `type` 设置为 `bootstrap.kubernetes.io/token` 可以创建
启动引导令牌类型的 Secret。这种类型的 Secret 被设计用来支持节点的启动引导过程。
其中包含用来为周知的 ConfigMap 签名的令牌。

<!--
A bootstrap token Secret is usually created in the `kube-system` namespace and
named in the form `bootstrap-token-<token-id>` where `<token-id>` is a 6 character
string of the token ID.

As a Kubernetes manifest, a bootstrap token Secret might look like the
following:
-->
启动引导令牌 Secret 通常创建于 `kube-system` 名字空间内，并以
`bootstrap-token-<令牌 ID>` 的形式命名；其中 `<令牌 ID>` 是一个由 6 个字符组成
的字符串，用作令牌的标识。

以 Kubernetes 清单文件的形式，某启动引导令牌 Secret 可能看起来像下面这样：

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: bootstrap-token-5emitj
  namespace: kube-system
type: bootstrap.kubernetes.io/token
data:
  auth-extra-groups: c3lzdGVtOmJvb3RzdHJhcHBlcnM6a3ViZWFkbTpkZWZhdWx0LW5vZGUtdG9rZW4=
  expiration: MjAyMC0wOS0xM1QwNDozOToxMFo=
  token-id: NWVtaXRq
  token-secret: a3E0Z2lodnN6emduMXAwcg==
  usage-bootstrap-authentication: dHJ1ZQ==
  usage-bootstrap-signing: dHJ1ZQ==
```

<!--
A bootstrap type has the following keys specified under `data`:

- `token-id`: A random 6 character string as the token identifier. Required.
- `token-secret`: A random 16 character string as the actual token secret. Required.
- `description1`: A human-readable string that describes what the token is
  used for. Optional.
- `expiration`: An absolute UTC time using RFC3339 specifying when the token
  should be expired. Optional.
- `usage-bootstrap-<usage>`: A boolean flag indicating additional usage for
  the bootstrap token.
- `auth-extra-groups`: A comma-separated list of group names that will be
  authenticated as in addition to the `system:bootstrappers` group.
-->
启动引导令牌类型的 Secret 会在 `data` 字段中包含如下主键：

- `token-id`：由 6 个随机字符组成的字符串，作为令牌的标识符。必需。
- `token-secret`：由 16 个随机字符组成的字符串，包含实际的令牌机密。必需。
- `description`：供用户阅读的字符串，描述令牌的用途。可选。
- `expiration`：一个使用 RFC3339 来编码的 UTC 绝对时间，给出令牌要过期的时间。可选。
- `usage-bootstrap-<usage>`：布尔类型的标志，用来标明启动引导令牌的其他用途。
- `auth-extra-groups`：用逗号分隔的组名列表，身份认证时除被认证为
  `system:bootstrappers` 组之外，还会被添加到所列的用户组中。

<!--
The above YAML may look confusing because the values are all in base64 encoded
strings. In fact, you can create an identical Secret using the following YAML:

```yaml
apiVersion: v1
kind: Secret
metadata:
  # Note how the Secret is named
  name: bootstrap-token-5emitj
  # A bootstrap token Secret usually resides in the kube-system namespace
  namespace: kube-system
type: bootstrap.kubernetes.io/token
stringData:
  auth-extra-groups: "system:bootstrappers:kubeadm:default-node-token"
  expiration: "2020-09-13T04:39:10Z"
  # This token ID is used in the name
  token-id: "5emitj"
  token-secret: "kq4gihvszzgn1p0r"
  # This token can be used for authentication
  usage-bootstrap-authentication: "true"
  # and it can be used for signing
  usage-bootstrap-signing: "true"
```
-->
上面的 YAML 文件可能看起来令人费解，因为其中的数值均为 base64 编码的字符串。
实际上，你完全可以使用下面的 YAML 来创建一个一模一样的 Secret：

```yaml
apiVersion: v1
kind: Secret
metadata:
  # 注意 Secret 的命名方式
  name: bootstrap-token-5emitj
  # 启动引导令牌 Secret 通常位于 kube-system 名字空间
  namespace: kube-system
type: bootstrap.kubernetes.io/token
stringData:
  auth-extra-groups: "system:bootstrappers:kubeadm:default-node-token"
  expiration: "2020-09-13T04:39:10Z"
  # 此令牌 ID 被用于生成 Secret 名称
  token-id: "5emitj"
  token-secret: "kq4gihvszzgn1p0r"
  # 此令牌还可用于 authentication （身份认证）
  usage-bootstrap-authentication: "true"
  # 且可用于 signing （证书签名）
  usage-bootstrap-signing: "true"
```

<!--
## Immutable Secrets {#secret-immutable}
-->
## 不可更改的 Secret {#secret-immutable}

{{< feature-state for_k8s_version="v1.21" state="stable" >}}

<!--
Kubernetes lets you mark specific Secrets (and ConfigMaps) as _immutable_.
Preventing changes to the data of an existing Secret has the following benefits:

- protects you from accidental (or unwanted) updates that could cause applications outages
- (for clusters that extensively use Secrets - at least tens of thousands of unique Secret
  to Pod mounts), switching to immutable Secrets improves the performance of your cluster
  by significantly reducing load on kube-apiserver. The kubelet does not need to maintain
  a [watch] on any Secrets that are marked as immutable.
-->
Kubernetes 允许你将特定的 Secret（和 ConfigMap）标记为 **不可更改（Immutable）**。
禁止更改现有 Secret 的数据有下列好处：

- 防止意外（或非预期的）更新导致应用程序中断
- （对于大量使用 Secret 的集群而言，至少数万个不同的 Secret 供 Pod 挂载），
  通过将 Secret 标记为不可变，可以极大降低 kube-apiserver 的负载，提升集群性能。
  kubelet 不需要监视那些被标记为不可更改的 Secret。

<!--
### Marking a Secret as immutable {#secret-immutable-create}

You can create an immutable Secret by setting the `immutable` field to `true`. For example,
-->
### 将 Secret 标记为不可更改   {#secret-immutable-create}

你可以通过将 Secret 的 `immutable` 字段设置为 `true` 创建不可更改的 Secret。
例如：

```yaml
apiVersion: v1
kind: Secret
metadata:
  ...
data:
  ...
immutable: true
```

<!--
You can also update any existing mutable Secret to make it immutable.
-->
你也可以更改现有的 Secret，令其不可更改。

{{< note >}}
<!--
Once a Secret or ConfigMap is marked as immutable, it is _not_ possible to revert this change
nor to mutate the contents of the `data` field. You can only delete and recreate the Secret.
Existing Pods maintain a mount point to the deleted Secret - it is recommended to recreate
these pods.
-->
一旦一个 Secret 或 ConfigMap 被标记为不可更改，撤销此操作或者更改 `data`
字段的内容都是 **不** 可能的。
只能删除并重新创建这个 Secret。现有的 Pod 将维持对已删除 Secret 的挂载点 --
建议重新创建这些 Pod。
{{< /note >}}

<!--
## Information security for Secrets

Although ConfigMap and Secret work similarly, Kubernetes applies some additional
protection for Secret objects.
-->
## Secret 的信息安全问题

尽管 ConfigMap 和 Secret 的工作方式类似，但 Kubernetes 对 Secret 有一些额外的保护。

<!--
Secrets often hold values that span a spectrum of importance, many of which can
cause escalations within Kubernetes (e.g. service account tokens) and to
external systems. Even if an individual app can reason about the power of the
Secrets it expects to interact with, other apps within the same namespace can
render those assumptions invalid.
-->
Secret 通常保存重要性各异的数值，其中很多都可能会导致 Kubernetes 中
（例如，服务账号令牌）或对外部系统的特权提升。
即使某些个别应用能够推导它期望使用的 Secret 的能力，
同一名字空间中的其他应用可能会让这种假定不成立。

<!--
A Secret is only sent to a node if a Pod on that node requires it.
For mounting secrets into Pods, the kubelet stores a copy of the data into a `tmpfs`
so that the confidential data is not written to durable storage.
Once the Pod that depends on the Secret is deleted, the kubelet deletes its local copy
of the confidential data from the Secret.
-->
只有当某个节点上的 Pod 需要某 Secret 时，对应的 Secret 才会被发送到该节点上。
如果将 Secret 挂载到 Pod 中，kubelet 会将数据的副本保存在在 `tmpfs` 中，
这样机密的数据不会被写入到持久性存储中。
一旦依赖于该 Secret 的 Pod 被删除，kubelet 会删除来自于该 Secret 的机密数据的本地副本。

<!--
There may be several containers in a Pod. By default, containers you define
only have access to the default ServiceAccount and its related Secret.
You must explicitly define environment variables or map a volume into a
container in order to provide access to any other Secret.
-->
同一个 Pod 中可能包含多个容器。默认情况下，你所定义的容器只能访问默认 ServiceAccount
及其相关 Secret。你必须显式地定义环境变量或者将卷映射到容器中，才能为容器提供对其他
Secret 的访问。

<!--
There may be Secrets for several Pods on the same node. However, only the
Secrets that a Pod requests are potentially visible within its containers.
Therefore, one Pod does not have access to the Secrets of another Pod.
-->
针对同一节点上的多个 Pod 可能有多个 Secret。不过，只有某个 Pod 所请求的 Secret
才有可能对 Pod 中的容器可见。因此，一个 Pod 不会获得访问其他 Pod 的 Secret 的权限。

{{< warning >}}
<!--
Any privileged containers on a node are liable to have access to all Secrets used
on that node.
-->
节点上的所有特权容器都可能访问到该节点上使用的所有 Secret。
{{< /warning >}}

<!--
### Security recommendations for developers

- Applications still need to protect the value of confidential information after reading it
  from an environment variable or volume. For example, your application must avoid logging
  the secret data in the clear or transmitting it to an untrusted party.
- If you are defining multiple containers in a Pod, and only one of those
  containers needs access to a Secret, define the volume mount or environment
  variable configuration so that the other containers do not have access to that
  Secret.
-->
### 针对开发人员的安全性建议

- 应用在从环境变量或卷中读取了机密信息内容之后仍要对其进行保护。例如，
  你的应用应该避免用明文的方式将 Secret 数据写入日志，或者将其传递给不可信的第三方。
- 如果你在一个 Pod 中定义了多个容器，而只有一个容器需要访问某 Secret，
  定义卷挂载或环境变量配置时，应确保其他容器无法访问该 Secret。
<!--
- If you configure a Secret through a {{< glossary_tooltip text="manifest" term_id="manifest" >}},
  with the secret data encoded as base64, sharing this file or checking it in to a
  source repository means the secret is available to everyone who can read the manifest.
  Base64 encoding is _not_ an encryption method, it provides no additional confidentiality
  over plain text.
-->
- 如果你通过{{< glossary_tooltip text="清单" term_id="manifest" >}}来配置某 Secret，
  Secret 数据以 Base64 的形式编码，将此文件共享，或者将其检入到某源码仓库，
  都意味着 Secret 对于任何可以读取清单的人都是可见的。
  Base64 编码 **不是** 一种加密方法，与明文相比没有任何安全性提升。
<!--
- When deploying applications that interact with the Secret API, you should
  limit access using
  [authorization policies](/docs/reference/access-authn-authz/authorization/) such as
  [RBAC]( /docs/reference/access-authn-authz/rbac/).
-->
- 部署与 Secret API 交互的应用时，你应该使用 [RBAC](/zh/docs/reference/access-authn-authz/rbac/)
  这类[鉴权策略](/zh/docs/reference/access-authn-authz/authorization/)来限制访问。
<!--
- In the Kubernetes API, `watch` and `list` requests for Secrets within a namespace
  are extremely powerful capabilities. Avoid granting this access where feasible, since
  listing Secrets allows the clients to inspect the values of every Secret in that
  namespace.
-->
- 在 Kubernetes API 中，名字空间内对 Secret 对象的 `watch` 和 `list` 请求是非常强大的能力。
  在可能的时候应该避免授予这类访问权限，因为通过列举 Secret，
  客户端能够查看对应名字空间内所有 Secret 的取值。

<!--
### Security recommendations for cluster administrators
-->
### 针对集群管理员的安全性建议

{{< caution >}}
<!--
A user who can create a Pod that uses a Secret can also see the value of that Secret. Even
if cluster policies do not allow a user to read the Secret directly, the same user could
have access to run a Pod that then exposes the Secret.
-->
能够创建使用 Secret 的 Pod 的用户也可以查看该 Secret 的取值。
即使集群策略不允许某用户直接读取 Secret 对象，这一用户仍然可以通过运行一个
Pod 来访问 Secret 的内容。
{{< /caution >}}

<!--
- Reserve the ability to `watch` or `list` all secrets in a cluster (using the Kubernetes
  API), so that only the most privileged, system-level components can perform this action.
- When deploying applications that interact with the Secret API, you should
  limit access using
  [authorization policies](/docs/reference/access-authn-authz/authorization/) such as
  [RBAC]( /docs/reference/access-authn-authz/rbac/).
-->
- 保留（使用 Kubernetes API）对集群中所有 Secret 对象执行 `watch` 或 `list` 操作的能力，
  这样只有特权级最高、系统级别的组件能够执行这类操作。
- 在部署需要通过 Secret API 交互的应用时，你应该通过使用
  [RBAC](/zh/docs/reference/access-authn-authz/rbac/)
  这类[鉴权策略](/zh/docs/reference/access-authn-authz/authorization/)来限制访问。
<!--
- In the API server, objects (including Secrets) are persisted into
  {{< glossary_tooltip term_id="etcd" >}}; therefore:
  - only allow cluster admistrators to access etcd (this includes read-only access);
  - enable [encryption at rest](/docs/tasks/administer-cluster/encrypt-data/)
    for Secret objects, so that the data of these Secrets are not stored in the clear
    into {{< glossary_tooltip term_id="etcd" >}};
  - consider wiping / shredding the durable storage used by etcd once it is
    no longer in use;
  - if there are multiple etcd instances, make sure that etcd is
    using SSL/TLS for communication between etcd peers.
-->
- 在 API 服务器上，对象（包括 Secret）会被持久化到 {{< glossary_tooltip term_id="etcd" >}} 中；
  因此：

  - 只应准许集群管理员访问 etcd（包括只读访问）；
  - 为 Secret 对象启用[静态加密](/zh/docs/tasks/administer-cluster/encrypt-data/)，
    这样这些 Secret 的数据就不会以明文的形式保存到
    {{< glossary_tooltip term_id="etcd" >}} 中；
  - 当 etcd 的持久化存储不再被使用时，请考虑彻底擦除存储介质；
  - 如果存在多个 etcd 实例，请确保 etcd 使用 SSL/TLS 来完成其对等通信。

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

<!--
- Learn how to [manage Secret using `kubectl`](/docs/tasks/configmap-secret/managing-secret-using-kubectl/)
- Learn how to [manage Secret using config file](/docs/tasks/configmap-secret/managing-secret-using-config-file/)
- Learn how to [manage Secret using kustomize](/docs/tasks/configmap-secret/managing-secret-using-kustomize/)
- Read the [API reference](/docs/reference/kubernetes-api/config-and-storage-resources/secret-v1/) for `Secret`
-->
- 学习如何[使用 `kubectl` 管理 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-kubectl/)
- 学习如何[使用配置文件管理 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-config-file/)
- 学习如何[使用 kustomize 管理 Secret](/zh/docs/tasks/configmap-secret/managing-secret-using-kustomize/)
- 阅读 [API 参考](/zh/docs/reference/kubernetes-api/config-and-storage-resources/secret-v1/)了解 `Secret`