Pod数据传递

<1>使用环境变量传递参数

在.yaml文件的container部分使用

env:
- name: DEMO_PARAM1
  value: "Parameter from the environment"

设置参数
podenv.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: podenv-demo
  labels:
    purpose: demo-podenv
spec:
  containers:
  - name: podenv-demo-container
    image: busybox
    env:
    - name: DEMO_PARAM1
      value: "Parameter from the environment"
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo $(DEMO_PARAM1); sleep 10; done"]

执行命令

kubectl apply -f podenv.yaml

进入pod

kubectl -it exec podenv-demo /bin/sh

查看参数

printenv

可看到传入的参数

...
DEMO_PARAM1=Parameter from the environment
...

<2>使用Secret

创建Secret

kubectl create secret generic test-secret --from-literal=username='admin' --from-literal=password='testsecret123'

• 将secret数据作为文件在pod中通过volume访问

secretpod-volume.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: secret-test-pod
spec:
  containers:
    - name: test-container
      image: nginx
      volumeMounts:
        - name: secret-volume
          mountPath: /etc/secret-volume
  volumes:
    - name: secret-volume
      secret:
        secretName: test-secret

生成pod执行命令

kubectl apply -f secretpod-volume.yaml

进入pod查看

kubectl -it exec secret-test-pod /bin/sh

在/etc/secret-volume下有对应的secret数据

password  username

• 通过创建环境变量的方式访问secret数据

secretpod-keyref.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: secret-envars-test-pod
spec:
  containers:
  - name: envars-test-container
    image: nginx
    env:
    - name: SECRET_USERNAME
      valueFrom:
        secretKeyRef:
          name: test-secret
          key: username
    - name: SECRET_PASSWORD
      valueFrom:
        secretKeyRef:
          name: test-secret
          key: password

创建Pod

kubectl apply -f secretpod-keyref.yaml

进入Pod

kubectl -it exec secret-envars-test-pod /bin/sh

显示环境变量
执行命令
printenv

...
SECRET_USERNAME=admin
SECRET_PASSWORD=testsecret123
...

取得Pod配置信息

取得Pod的信息挂载的volume
podvolumelabel.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: kubernetes-downwardapi-volume-example
  labels:
    zone: ue-est-coast
    cluster: test-cluster1
    rack: rack-22
  annotations:
    build: two
    builder: john-doe
spec:
  containers:
    - name: client-container
      image: busybox
      command: ["sh", "-c"]
      args:
      - while true; do
          if [[ -e /etc/podinfo/labels ]]; then
            echo -en '\n\n'; cat /etc/podinfo/labels; fi;
          if [[ -e /etc/podinfo/annotations ]]; then
            echo -en '\n\n'; cat /etc/podinfo/annotations; fi;
          sleep 5;
        done;
      volumeMounts:
        - name: podinfo
          mountPath: /etc/podinfo
          readOnly: false
  volumes:
    - name: podinfo
      downwardAPI:
        items:
          - path: "labels"
            fieldRef:
              fieldPath: metadata.labels
          - path: "annotations"
            fieldRef:
              fieldPath: metadata.annotations

创建Pod

kubectl apply -f getpodinf.yaml

进入Pod

kubectl -it exec k8s-downwardapi-demo /bin/sh

查看/etc/podinfo下有如下文件

annotations  labels

取得容器配置信息

取得容器的配置信息如请求内存，CPU资源，内存，CPU限定资源等
podvolumeresourceref.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: k8s-downwardapi-volume-resourceref
spec:
  containers:
    - name: resourceref-container
      image: busybox
      command: ["sh", "-c"]
      args:
      - while true; do
          echo -en '\n';
          if [[ -e /etc/podinfo/cpu_limit ]]; then
            echo -en '\n'; cat /etc/podinfo/cpu_limit; fi;
          if [[ -e /etc/podinfo/cpu_request ]]; then
            echo -en '\n'; cat /etc/podinfo/cpu_request; fi;
          if [[ -e /etc/podinfo/mem_limit ]]; then
            echo -en '\n'; cat /etc/podinfo/mem_limit; fi;
          if [[ -e /etc/podinfo/mem_request ]]; then
            echo -en '\n'; cat /etc/podinfo/mem_request; fi;
          sleep 5;
        done;
      resources:
        requests:
          memory: "32Mi"
          cpu: "125m"
        limits:
          memory: "64Mi"
          cpu: "250m"
      volumeMounts:
        - name: podinfo
          mountPath: /etc/podinfo
          readOnly: false
  volumes:
    - name: podinfo
      downwardAPI:
        items:
          - path: "cpu_limit"
            resourceFieldRef:
              containerName: resourceref-container
              resource: limits.cpu
              divisor: 1m
          - path: "cpu_request"
            resourceFieldRef:
              containerName: resourceref-container
              resource: requests.cpu
              divisor: 1m
          - path: "mem_limit"
            resourceFieldRef:
              containerName: resourceref-container
              resource: limits.memory
              divisor: 1Mi
          - path: "mem_request"
            resourceFieldRef:
              containerName: resourceref-container
              resource: requests.memory
              divisor: 1Mi

创建Pod

kubectl apply -f podvolumeresourceref.yaml 

进入Pod

kubectl -it exec k8s-downwardapi-volume-resourceref /bin/sh

查看/etc/podinfo下有如下文件

cpu_limit    cpu_request  mem_limit    mem_request

用Pod字段作为环境变量

在实际应用中Pod的name，IP等都需要在程序中取得，可以通过将Pod的这些值设为环境变量来获取
podvaluesenv.yaml内容如下

apiVersion: v1
kind: Pod
metadata:
  name: podvalue-env-fieldref
spec:
  containers:
    - name: podvalue-demo-container
      image: 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

创建Pod

kubectl apply -f podvalueasenv.yaml

进入Pod

kubectl -it exec podvalue-env-fieldref /bin/sh

执行命令printenv查看环境变量

...
MY_POD_SERVICE_ACCOUNT=default
MY_POD_NAMESPACE=default
MY_POD_IP=172.20.2.93
MY_NODE_NAME=xxxxx
MY_POD_NAME=podvalue-env-fieldref
...

容器字段的值作为环境变量

获取容器的CPU，内存limit的值，CPU，内存的request的值作为Pod的环境变量

.yaml文件内容如下

apiVersion: v1
kind: Pod
metadata:
  name: containervalue-env-resourcefieldref
spec:
  containers:
    - name: cvenv-test-container
      image: busybox
      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: cvenv-test-container
              resource: limits.cpu
        - name: MY_CPU_LIMIT
          valueFrom:
            resourceFieldRef:
              containerName: cvenv-test-container
              resource: limits.cpu
        - name: MY_MEM_REQUEST
          valueFrom:
            resourceFieldRef:
              containerName: cvenv-test-container
              resource: requests.memory
        - name: MY_MEM_LIMIT
          valueFrom:
            resourceFieldRef:
              containerName: cvenv-test-container
              resource: limits.memory
  restartPolicy: Never

创建Pod

kubectl -it exec containervalue-env-resourcefieldref /bin/sh

进入Pod

kubectl -it exec containervalue-env-resourcefieldref /bin/sh

执行命令printenv查看环境变量

...
MY_MEM_LIMIT=67108864
MY_CPU_LIMIT=1
MY_MEM_REQUEST=33554432
MY_CPU_REQUEST=1
...