212 lines
7.3 KiB
Markdown
212 lines
7.3 KiB
Markdown
---
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title: 为容器设置环境变量
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content_type: task
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weight: 20
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---
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<!--
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title: Define Environment Variables for a Container
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content_type: task
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weight: 20
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-->
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<!-- overview -->
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<!--
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This page shows how to define environment variables for a container
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in a Kubernetes Pod.
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-->
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本页将展示如何为 Kubernetes Pod 下的容器设置环境变量。
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## {{% heading "prerequisites" %}}
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{{< include "task-tutorial-prereqs.md" >}}
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<!-- steps -->
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<!--
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## Define an environment variable for a container
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-->
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## 为容器设置一个环境变量 {#define-an-env-variable-for-a-container}
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<!--
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When you create a Pod, you can set environment variables for the containers
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that run in the Pod. To set environment variables, include the `env` or
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`envFrom` field in the configuration file.
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-->
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创建 Pod 时，可以为其下的容器设置环境变量。通过配置文件的 `env` 或者 `envFrom` 字段来设置环境变量。
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<!--
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The `env` and `envFrom` fields have different effects.
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`env`
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: allows you to set environment variables for a container, specifying a value directly for each variable that you name.
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-->
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`env` 和 `envFrom` 字段具有不同的效果。
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`env`
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：可以为容器设置环境变量，直接为你所给的每个变量指定一个值。
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<!--
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`envFrom`
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: allows you to set environment variables for a container by referencing either a ConfigMap or a Secret.
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When you use `envFrom`, all the key-value pairs in the referenced ConfigMap or Secret
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are set as environment variables for the container.
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You can also specify a common prefix string.
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-->
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`envFrom`
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：你可以通过引用 ConfigMap 或 Secret 来设置容器的环境变量。
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使用 `envFrom` 时，引用的 ConfigMap 或 Secret 中的所有键值对都被设置为容器的环境变量。
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你也可以指定一个通用的前缀字符串。
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<!--
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You can read more about [ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/#configure-all-key-value-pairs-in-a-configmap-as-container-environment-variables)
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and [Secret](/docs/tasks/inject-data-application/distribute-credentials-secure/#configure-all-key-value-pairs-in-a-secret-as-container-environment-variables).
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This page explains how to use `env`.
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-->
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你可以阅读有关 [ConfigMap](/zh-cn/docs/tasks/configure-pod-container/configure-pod-configmap/#configure-all-key-value-pairs-in-a-configmap-as-container-environment-variables)
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和 [Secret](/zh-cn/docs/tasks/inject-data-application/distribute-credentials-secure/#configure-all-key-value-pairs-in-a-secret-as-container-environment-variables)
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的更多信息。
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本页介绍如何使用 `env`。
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<!--
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In this exercise, you create a Pod that runs one container. The configuration
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file for the Pod defines an environment variable with name `DEMO_GREETING` and
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value `"Hello from the environment"`. Here is the configuration manifest for the
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Pod:
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-->
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本示例中，将创建一个只包含单个容器的 Pod。此 Pod 的配置文件中设置环境变量的名称为 `DEMO_GREETING`，
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其值为 `"Hello from the environment"`。下面是此 Pod 的配置清单：
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{{% code_sample file="pods/inject/envars.yaml" %}}
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<!--
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1. Create a Pod based on that manifest:
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-->
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1. 基于配置清单创建一个 Pod：
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```shell
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kubectl apply -f https://k8s.io/examples/pods/inject/envars.yaml
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```
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<!--
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1. List the running Pods:
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-->
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2. 获取正在运行的 Pod 信息：
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```shell
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kubectl get pods -l purpose=demonstrate-envars
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```
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<!--
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The output is similar to this:
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-->
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查询结果应为：
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```
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NAME READY STATUS RESTARTS AGE
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envar-demo 1/1 Running 0 9s
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```
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<!--
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1. List the Pod's container environment variables:
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-->
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3. 列出 Pod 容器的环境变量：
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```shell
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kubectl exec envar-demo -- printenv
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```
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<!--
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The output is similar to this:
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-->
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打印结果应为：
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```
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NODE_VERSION=4.4.2
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EXAMPLE_SERVICE_PORT_8080_TCP_ADDR=10.3.245.237
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HOSTNAME=envar-demo
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...
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DEMO_GREETING=Hello from the environment
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DEMO_FAREWELL=Such a sweet sorrow
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```
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{{< note >}}
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<!--
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The environment variables set using the `env` or `envFrom` field
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override any environment variables specified in the container image.
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-->
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通过 `env` 或 `envFrom` 字段设置的环境变量将覆盖容器镜像中指定的所有环境变量。
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{{< /note >}}
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{{< note >}}
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<!--
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Environment variables may reference each other, however ordering is important.
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Variables making use of others defined in the same context must come later in
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the list. Similarly, avoid circular references.
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-->
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环境变量可以互相引用，但是顺序很重要。
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使用在相同上下文中定义的其他变量的变量必须在列表的后面。
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同样，请避免使用循环引用。
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{{< /note >}}
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<!--
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## Using environment variables inside of your config
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Environment variables that you define in a Pod's configuration under
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`.spec.containers[*].env[*]` can be used elsewhere in the configuration, for
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example in commands and arguments that you set for the Pod's containers.
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In the example configuration below, the `GREETING`, `HONORIFIC`, and
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`NAME` environment variables are set to `Warm greetings to`, `The Most
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Honorable`, and `Kubernetes`, respectively. The environment variable
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`MESSAGE` combines the set of all these environment variables and then uses it
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as a CLI argument passed to the `env-print-demo` container.
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-->
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## 在配置中使用环境变量 {#using-env-var-inside-of-your-config}
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你在 Pod 的配置中定义的、位于 `.spec.containers[*].env[*]` 下的环境变量
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可以在配置的其他地方使用，例如可用在为 Pod 的容器设置的命令和参数中。
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在下面的示例配置中，环境变量 `GREETING`、`HONORIFIC` 和 `NAME` 分别设置为 `Warm greetings to`、
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`The Most Honorable` 和 `Kubernetes`。
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环境变量 `MESSAGE` 将所有这些环境变量的集合组合起来，
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然后再传递给容器 `env-print-demo` 的 CLI 参数中使用。
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```yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: print-greeting
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spec:
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containers:
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- name: env-print-demo
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image: bash
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env:
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- name: GREETING
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value: "Warm greetings to"
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- name: HONORIFIC
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value: "The Most Honorable"
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- name: NAME
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value: "Kubernetes"
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command: ["echo"]
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args: ["$(GREETING) $(HONORIFIC) $(NAME)"]
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```
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<!--
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Upon creation, the command `echo Warm greetings to The Most Honorable Kubernetes` is run on the container.
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-->
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创建后，命令 `echo Warm greetings to The Most Honorable Kubernetes` 将在容器中运行。
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## {{% heading "whatsnext" %}}
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<!--
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* Learn more about [environment variables](/docs/tasks/inject-data-application/environment-variable-expose-pod-information/).
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* Learn about [using secrets as environment variables](/docs/concepts/configuration/secret/#using-secrets-as-environment-variables).
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* See [EnvVarSource](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#envvarsource-v1-core).
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-->
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* 进一步了解[环境变量](/zh-cn/docs/tasks/inject-data-application/environment-variable-expose-pod-information/)
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* 进一步了解[通过环境变量来使用 Secret](/zh-cn/docs/concepts/configuration/secret/#using-secrets-as-environment-variables)
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* 关于 [EnvVarSource](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#envvarsource-v1-core) 资源的信息。
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