131 lines
4.0 KiB
Markdown
131 lines
4.0 KiB
Markdown
---
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title: 为容器设置环境变量
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content_template: templates/task
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---
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{{% capture overview %}}
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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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{{% /capture %}}
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{{% capture prerequisites %}}
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{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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{{% /capture %}}
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{{% capture steps %}}
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## 为容器设置一个环境变量
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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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本示例中，将创建一个只包含单个容器的 Pod。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 Pod 的配置文件内容：
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{{< codenew file="pods/inject/envars.yaml" >}}
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1. 基于 YAML 文件创建一个 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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1. 获取一下当前正在运行的 Pods 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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查询结果应为：
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```shell
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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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1. 进入该 Pod 下的容器并打开一个命令终端：
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```shell
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kubectl exec -it envar-demo -- /bin/bash
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```
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1. 在命令终端中通过执行 `printenv` 打印出环境变量。
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```shell
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root@envar-demo:/# printenv
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```
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打印结果应为：
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```shell
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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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1. 通过键入 `exit` 退出命令终端。
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<!--
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{{< note >}}
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The environment variables set using the `env` or `envFrom` field
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will override any environment variables specified in the container image.
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{{< /note >}}
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-->
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{{< note >}}
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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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<!--
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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 can be used elsewhere in the configuration, for example in commands and arguments that you set for the Pod's containers. In the example configuration below, the `GREETING`, `HONORIFIC`, and `NAME` environment variables are set to `Warm greetings to`, `The Most Honorable`, and `Kubernetes`, respectively. Those environment variables are then used in the CLI arguments 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
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您在 Pod 的配置中定义的环境变量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。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` ，`The Most Honorable` 和 `Kubernetes`。然后这些环境变量在传递给容器 `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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{{% /capture %}}
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{{% capture whatsnext %}}
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* 有关环境变量的更多信息，请参阅[这里](/docs/tasks/inject-data-application/environment-variable-expose-pod-information/)。
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* 有关如何通过环境变量来使用 Secret，请参阅[这里](/docs/user-guide/secrets/#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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{{% /capture %}}
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