`pods/inject/dapi-envars-pod.yaml`
apiVersion: v1 kind: Pod metadata: name: dapi-envars-fieldref spec: containers: - name: test-container image: k8s.gcr.io/busybox command: [ "sh", "-c"] args: - while true; do echo -en '\n'; printenv MY_NODE_NAME MY_POD_NAME MY_POD_NAMESPACE; printenv MY_POD_IP MY_POD_SERVICE_ACCOUNT; sleep 10; done; env: - name: MY_NODE_NAME valueFrom: fieldRef: fieldPath: spec.nodeName - name: MY_POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: MY_POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace - name: MY_POD_IP valueFrom: fieldRef: fieldPath: status.podIP - name: MY_POD_SERVICE_ACCOUNT valueFrom: fieldRef: fieldPath: spec.serviceAccountName restartPolicy: Never

pods/inject/dapi-envars-pod.yaml Copy pods/inject/dapi-envars-pod.yaml to clipboard

apiVersion: v1
kind: Pod
metadata:
  name: dapi-envars-fieldref
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
      command: [ "sh", "-c"]
      args:
      - while true; do
          echo -en '\n';
          printenv MY_NODE_NAME MY_POD_NAME MY_POD_NAMESPACE;
          printenv MY_POD_IP MY_POD_SERVICE_ACCOUNT;
          sleep 10;
        done;
      env:
        - name: MY_NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        - name: MY_POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: MY_POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: MY_POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        - name: MY_POD_SERVICE_ACCOUNT
          valueFrom:
            fieldRef:
              fieldPath: spec.serviceAccountName
  restartPolicy: Never

这个配置文件中，你可以看到五个环境变量。env字段是一个EnvVars类型的数组。数组中第一个元素指定MY_NODE_NAME这个环境变量从Pod的spec.nodeName字段获取变量值。同样，其它环境变量也是从Pod的字段获取它们的变量值。

注意： 本示例中的字段是Pod字段，不是Pod中容器的字段。

创建Pod：

kubectl apply -f https://k8s.io/examples/pods/inject/dapi-envars-pod.yaml

验证Pod中的容器运行正常：

kubectl get pods

查看容器日志：

kubectl logs dapi-envars-fieldref

输出信息显示了所选择的环境变量的值：

minikube
dapi-envars-fieldref
default
172.17.0.4
default

要了解为什么这些值在日志中，请查看配置文件中的command 和 args字段。当容器启动时，它将五个环境变量的值写入stdout。每十秒重复执行一次。

接下来，进入Pod中运行的容器，打开一个shell：

kubectl exec -it dapi-envars-fieldref -- sh

在shell中，查看环境变量：

/# printenv

输出信息显示环境变量已经指定为Pod的字段的值。

MY_POD_SERVICE_ACCOUNT=default
...
MY_POD_NAMESPACE=default
MY_POD_IP=172.17.0.4
...
MY_NODE_NAME=minikube
...
MY_POD_NAME=dapi-envars-fieldref

用容器字段作为环境变量的值

前面的练习中，你将Pod字段作为环境变量的值。接下来这个练习，你将用容器字段作为环境变量的值。这里是包含一个容器的pod的配置文件：

`pods/inject/dapi-envars-container.yaml`
apiVersion: v1 kind: Pod metadata: name: dapi-envars-resourcefieldref spec: containers: - name: test-container image: k8s.gcr.io/busybox:1.24 command: [ "sh", "-c"] args: - while true; do echo -en '\n'; printenv MY_CPU_REQUEST MY_CPU_LIMIT; printenv MY_MEM_REQUEST MY_MEM_LIMIT; sleep 10; done; resources: requests: memory: "32Mi" cpu: "125m" limits: memory: "64Mi" cpu: "250m" env: - name: MY_CPU_REQUEST valueFrom: resourceFieldRef: containerName: test-container resource: requests.cpu - name: MY_CPU_LIMIT valueFrom: resourceFieldRef: containerName: test-container resource: limits.cpu - name: MY_MEM_REQUEST valueFrom: resourceFieldRef: containerName: test-container resource: requests.memory - name: MY_MEM_LIMIT valueFrom: resourceFieldRef: containerName: test-container resource: limits.memory restartPolicy: Never

pods/inject/dapi-envars-container.yaml Copy pods/inject/dapi-envars-container.yaml to clipboard

apiVersion: v1
kind: Pod
metadata:
  name: dapi-envars-resourcefieldref
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox:1.24
      command: [ "sh", "-c"]
      args:
      - while true; do
          echo -en '\n';
          printenv MY_CPU_REQUEST MY_CPU_LIMIT;
          printenv MY_MEM_REQUEST MY_MEM_LIMIT;
          sleep 10;
        done;
      resources:
        requests:
          memory: "32Mi"
          cpu: "125m"
        limits:
          memory: "64Mi"
          cpu: "250m"
      env:
        - name: MY_CPU_REQUEST
          valueFrom:
            resourceFieldRef:
              containerName: test-container
              resource: requests.cpu
        - name: MY_CPU_LIMIT
          valueFrom:
            resourceFieldRef:
              containerName: test-container
              resource: limits.cpu
        - name: MY_MEM_REQUEST
          valueFrom:
            resourceFieldRef:
              containerName: test-container
              resource: requests.memory
        - name: MY_MEM_LIMIT
          valueFrom:
            resourceFieldRef:
              containerName: test-container
              resource: limits.memory
  restartPolicy: Never

这个配置文件中，你可以看到四个环境变量。env字段是一个EnvVars 类型的数组。数组中第一个元素指定MY_CPU_REQUEST这个环境变量从容器的requests.cpu字段获取变量值。同样，其它环境变量也是从容器的字段获取它们的变量值。

创建Pod：

kubectl apply -f https://k8s.io/examples/pods/inject/dapi-envars-container.yaml

验证Pod中的容器运行正常：

kubectl get pods

查看容器日志：

kubectl logs dapi-envars-resourcefieldref

输出信息显示了所选择的环境变量的值：

接下来

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