|NO.Z.00175|——————————|CloudNative|——|KuberNetes&配置管理.V06|——|configmap.v06|使用configmap定义容器|

一、使用configmap数据定义容器

### --- 使用congfigmap数据定义容器环境变量
~~~     使用来自单个configmap的数据定义容器环境变量

[root@k8s-master01 configmap]# vim pod-single-configmap-env-variable.yaml
apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: busybox
      command: [ "/bin/sh", "-c", "env" ]
      env:
        # Define the environment variable
        - name: SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
              # The ConfigMap containing the value you want to assign to SPECIAL_LEVEL_KEY
              name: special-config
              # Specify the key associated with the value
              key: special.how
  restartPolicy: Never

二、查看变量执行结果

### --- 创建pod
~~~     现在，Pod的输出包括环境变量SPECIAL_LEVEL_KEY=very

[root@k8s-master01 configmap]# kubectl create -f pod-single-configmap-env-variable.yaml 
pod/dapi-test-pod created 

### --- 在创建pod的时候若是镜像拉取失败，可以更改使用本地镜像，不选择下载所有

[root@k8s-master01 configmap]# kubectl describe po busybox | grep Image
    Image:         busybox:1.28
    Image ID:      docker-pullable://busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47

### --- 查看创建的configmap.yaml配置文件

[root@k8s-master01 configmap]# vim pod-single-configmap-env-variable.yaml 
spec:
  nodeName: k8s-master02
  containers:
    - name: test-container
      image: busybox:1.28
      imagePullPolicy: IfNotPresent

### --- 查看创建的容器
~~~     Completed；执行这个变量后就退出了，所以显示正常状态。

[root@k8s-master01 configmap]# kubectl get po -owide
NAME                        READY   STATUS      RESTARTS   AGE     IP               NODE           NOMINATED NODE   READINESS GATES
dapi-test-pod               0/1     Completed   0          11m     172.27.14.215    k8s-node02     <none>           <none>

三、查看变量执行结果

### --- 查看这个环境变量
~~~     这种方式在生产环境下使用的不是很多，

[root@k8s-master01 configmap]# kubectl logs -f dapi-test-pod
SPECIAL_LEVEL_KEY=very
[root@k8s-master01 configmap]# kubectl get cm
NAME                          DATA   AGE
special-config                2      38m

[root@k8s-master01 configmap]# kubectl get cm special-config -oyaml  
  special.how: very                 // special.how的值是very，它被用于这个下面这个pod
[root@k8s-master01 configmap]# cat pod-single-configmap-env-variable.yaml
          valueFrom:
            configMapKeyRef:        // 这个pod把自己的值挂载到容器里面
              # The ConfigMap containing the value you want to assign to SPECIAL_LEVEL_KEY
              name: special-config
              # Specify the key associated with the value
              key: special.how      // 读取的key值为special.how；把它的值赋给了变量，叫做special_level_key

四、可以直接在配置文件中赋值定义变量

### --- 删除之前的pod

[root@k8s-master01 configmap]# kubectl delete -f pod-single-configmap-env-variable.yaml 
pod "dapi-test-pod" deleted

### --- 修改configmap.yaml配置参数
~~~     使用单个key的，肯定没有这种写法方便，使用单个key定义环境变量是很不理想的状态。

[root@k8s-master01 configmap]# vim pod-single-configmap-env-variable.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  nodeName: k8s-master02
  containers:
    - name: test-container
      image: busybox:1.28
      imagePullPolicy: IfNotPresent
      command: [ "/bin/sh", "-c", "env" ]
      envFrom:
      - configMapRef:
          name: special-config
      env:
        # Define the environment variable
        #- name: SPECIAL_LEVEL_KEY
        #  valueFrom:
        #    configMapKeyRef:
        #      # The ConfigMap containing the value you want to assign to SPECIAL_LEVEL_KEY
        #      name: special-config
        #      # Specify the key associated with the value
        #      key: special.how
        - name: test                # 直接写一个key-velel的形式
          value: test-value
        - name: musqlHostAddress
          value: 10.10.10.10
        - name: mysqlPort
          value: "3306"  #only string
  restartPolicy: Never

五、replace容器

### --- replace容器

[root@k8s-master01 configmap]# kubectl create -f pod-single-configmap-env-variable.yaml
pod/dapi-test-pod created
[root@k8s-master01 configmap]# kubectl get po -owide
NAME                        READY   STATUS      RESTARTS   AGE     IP               NODE           NOMINATED NODE   READINESS GATES
dapi-test-pod               0/1     Completed   0          18s     172.25.92.78     k8s-master02   <none>           <none>

### --- 查看打印的环境变量
~~~     # 形式一：读取configmap充当环境变量，
~~~     # 形式二：读取configmap定义配置文件。

[root@k8s-master01 configmap]# kubectl logs -f dapi-test-pod
mysqlPort=3306                  // 自动手动添加的
special.type=charm              // 从配置文件生成的；这个变量时从special-configmap中自动生成的。
special.how=very                // 从配置文件生成的

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart

                                                                                                                                                   ——W.S.Landor

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