概述

  • ConfigMap 通常用于设置环境变量、设置命令行参数、创建配置文件
  • Pod 使用 ConfigMap 前,ConfigMap 必须存在,否则 pod 不能启动
  • ConfigMap 只能被在同一一个命名空间中的Pod所引用

创建 ConfigMap

  • 命令如下

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    kubectl create configmap <map-name> <data-source>
    # 或者
    kubectl apply -f <configmap-file.yml>
  • map-name: ConfigMap 名称

  • data-source: 目录、文件或具体值

通过目录创建 ConfigMaps

  • 命令如下

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    kubectl create configmap game-config \
        --from-file=https://k8s.io/docs/tasks/configure-pod-container/configmap/kubectl
  • docs/tasks/configure-pod-container/configmap/kubectl/目录下的文件包括

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    ls docs/tasks/configure-pod-container/configmap/kubectl/
    • 输出如下

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      game.properties
      ui.properties
  • 查看 game-config 信息

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    kubectl describe configmaps game-config
    # 或者
    kubectl get configmaps game-config -o yaml

通过文件创建 ConfigMaps

  • 通过单个文件创建

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    kubectl create configmap game-config-2 \
        --from-file=https://k8s.io/docs/tasks/configure-pod-container/configmap/kubectl/game.properties
  • 通过多个文件创建

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    kubectl create configmap game-config-3 \
        --from-file=https://k8s.io/docs/tasks/configure-pod-container/configmap/kubectl/game.properties \
        --from-file=https://k8s.io/docs/tasks/configure-pod-container/configmap/kubectl/ui.properties
  • 通过文件创建ConfigMap时可以定义文件的键

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    kubectl create configmap game-config-4 \
        --from-file=game-special-key=https://k8s.io/docs/tasks/configure-pod-container/configmap/kubectl/game.properties
    # key 是 "game-special-key"
    # value 是 game.properties 文件的内容

通过具体值创建 ConfigMaps

  • 使用 –from-literal 参数定义具体值

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    kubectl create configmap special-config \
        --from-literal=special.how=very \
        --from-literal=special.type=charm

使用 ConfigMap

定义 pod 环境变量

Pod 环境变量的值来自于单一 ConfigMap

  • 在ConfigMap中定义一个环境变量作为键值对

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    kubectl create configmap special-config --from-literal=special.how=very
  • 指派ConfigMap中定义的special.how的值给Pod中SPECIAL_LEVEL_KEY环境变量

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/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
  • 保存Pod规格的变化,Pod将输出SPECIAL_LEVEL_KEY=very

Pod 环境变量的值来自于多个 ConfigMap

  • 创建两个 ConfigMap

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    ---
    apiVersion:v1
    kind:ConfigMap
    metadata:
       name:special-config
       namespace:default
    data:
       special.how:very
        
    ---
    apiVersion:v1
    kind:ConfigMap
    metadata:
       name:env-config
       namespace:default
    data:
       log_level:INFO
  • 在Pod规格中定义环境变量

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/busybox
        command:["/bin/sh","-c","env"]
        env:
        - name:SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
               name:special-config
               key:special.how
         - name:LOG_LEVEL
           valueFrom:
              configMapKeyRef:
                  name:env-config
                  key:log_level
      restartPolicy:Neverv
  • 保存变更后的Pod,Pod将会输出SPECIAL_LEVEL_KEY=very和LOG_LEVEL=info

在一个ConfigMap中配置的键值对都作为一个Pod的环境变量

  • Kubernetes v1.6+可用
  • 创建包含多个键-值对的ConfigMap

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    apiVersion:v1
    kind:ConfigMap
    metadata:
      name:special-config
      namespace:default
    data:
      SPECIAL_LEVEL:very
      SPECIAL_TYPE:charm
  • 使用envFrom定义所有的ConfigMap数据作为Pod的环境变量。来自于Config的键成为Pod中环境变量的名

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/busybox
        command:["/bin/sh","-c","env"]
        envFrom:
        - configMapRef:
            name:special-config
       restartPolicy:Never
  • Pod的输出包括: SPECIAL_LEVEL=very 和 SPECIAL_TYPE=charm

在Pod命令行中使用ConfigMap定义的环境变量

  • 在Pod规范的command 中使用$(VAR_NAME) ,获取ConfigMap定义的环境变量

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/busybox
        command:["/bin/sh","-c","echo $(SPECIAL_LEVEL_KEY) $(SPECIAL_TYPE_KEY)"]
        env:
        - name:SPECIAL_LEVEL_KEY
          valueFrom:
             configMapKeyRef:
                name:special-config
                key:SPECIAL_LEVEL
        - name:SPECIAL_TYPE_KEY
          valueFrom:
              configMapKeyRef:
                name:special-config
                key:SPECIAL_TYPE
      restartPolicy:Never
  • test-container容器的输出: very charm

添加ConfigMap数据至存储卷

  • 当通过–from-file创建的ConfigMap时,文件将作为一个键保存在ConfigMap中,而此文件的内容将作为值

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    apiVersion:v1
    kind:ConfigMap
    metadata:
      name:special-config
      namespace:default
    data:
      special.level:very
      special.type:charm

将ConfigMap中的数据传播到指定目录

  • 在Pod的存储卷区域添加ConfigMap的名称
  • 这将添加ConfigMap数据到volumeMounts.mountPath指定的目录下(此例为/etc/config)
  • command区域将引用保存在ConfigMap中的special.level条目

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/busybox
        command:["/bin/sh","-c","ls /etc/config/"]
        volumeMounts:
        - name:config-volume
          mountPath:/etc/config
      volumes:
      - name:config-volume
        configMap:
            # Provide the name of the ConfigMap containing the files you want
            # to add to the container
          name:special-config
      restartPolicy:Never
  • Pod运行时,command (“ls /etc/config/”)将输出: special.level special.type

  • 如果在/etc/config/目录下存在文件,将不会删除

添加ConfigMap数据至存储卷指定的目录

  • 为ConfigMap条目,使用path指定文件路径
  • 此例中,special.level将在config-volume存储卷中被挂接至/etc/config/keys

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    apiVersion:v1
    kind:Pod
    metadata:
      name:dapi-test-pod
    spec:
      containers:
      - name:test-container
        image:k8s.gcr.io/busybox
        command:["/bin/sh","-c","cat /etc/config/keys"]
        volumeMounts:
         - name:config-volume
           mountPath:/etc/config
      volumes:
      - name:config-volume
        configMap:
           name:special-config
           items:
           - key:special.level
             path:keys
      restartPolicy:Never
  • Pod运行时,(“cat /etc/config/keys”) 将输出: very

参考