Kubernetes外挂配置管理—ConfigMap介绍

你的名字 2022-03-22 03:58 144阅读 0赞

# [Kubernetes外挂配置管理—ConfigMap介绍][Kubernetes_ConfigMap] #

其他容器编排调度工具会大谈特谈“轻应用”、“十二要素应用”，这样就势必会对企业级复杂应用做很大的改动。Kubernetes是为了解决“如何合理使用容器支撑企业级复杂应用”这个问题而诞生的，所以它的设计理念是要支持绝大多数应用的原生形态。例如，很多应用程序的配置需要通过配置文件，命令行参数和环境变量的组合配置来完成（“十二要素应用”等均要求去配置）。这些配置应该从image内容中解耦，以此来保持容器化应用程序的可移植性。ConfigMap API资源提供了将配置数据注入容器的方式，同时保证该机制对容器来说是透明的。ConfigMap可以被用来保存单个属性，也可以用来保存整个配置文件或者JSON二进制大对象。

ConfigMap API资源存储键/值对配置数据，这些数据可以在pods里使用。ConfigMap跟Secrets类似，但是ConfigMap可以更方便的处理不包含敏感信息的字符串。示例如下：

kind: ConfigMap
    apiVersion: v1
    metadata:
      creationTimestamp: 2016-02-18T19:14:38Z
      name: example-config
      namespace: default
    data:
      example.property.1: hello
      example.property.2: world
      example.property.file: |-
        property.1=value-1
        property.2=value-2
        property.3=value-3

通过示例代码可以看到：ConfigMap可以包含细粒度的配置项，如：example.property.1；也可以包含粗粒度的配置文件，如：example.property.file。

## 1、创建ConfigMap ##

### 1.1 从文件夹创建 ###

[root@k8s-master propertirs]# cat /home/yaml/propertirs/game.properties 
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30
    [root@k8s-master propertirs]# cat /home/yaml/propertirs/ui.properties 
    color.good=purple
    color.bad=yellow
    allow.textmode=true
    how.nice.to.look=fairlyNice
    [root@k8s-master propertirs]# kubectl create configmap game-config --from-file=/home/yaml/propertirs/
    configmap "game-config" created
    [root@k8s-master propertirs]# kubectl describe configmaps game-config  
    #该方法只能得到ConfigMap的Key和size
    Name:        game-config
    Namespace:    default
    Labels:        <none>
    Annotations:    <none>
    
    Data
    ====
    ui.properties:        83 bytes
    game.properties:    158 bytes

#若想得到详细信息，可通过以下命令：

### 1.2 从文件创建 ###

[root@k8s-master propertirs]# kubectl create configmap game-config-2 --from-file=/home/yaml/propertirs/game.properties --from-file=/home/yaml/propertirs/ui.properties
    configmap "game-config-2" created
    [root@k8s-master propertirs]# kubectl get configmaps game-config-2 -o yaml
    apiVersion: v1
    data:
      game.properties: |
        enemies=aliens
        lives=3
        enemies.cheat=true
        enemies.cheat.level=noGoodRotten
        secret.code.passphrase=UUDDLRLRBABAS
        secret.code.allowed=true
        secret.code.lives=30
      ui.properties: |
        color.good=purple
        color.bad=yellow
        allow.textmode=true
        how.nice.to.look=fairlyNice
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T03:30:15Z
      name: game-config-2
      namespace: default
      resourceVersion: "3003415"
      selfLink: /api/v1/namespaces/default/configmaps/game-config-2
      uid: b2e4dfab-0de6-11e7-b3d5-fa163ebba51b

### 1.3  指定data中的key ###

[root@k8s-master propertirs]# kubectl create configmap game-config-3 --from-file=game-special-key=/home/yaml/propertirs/game.properties
    configmap "game-config-3" created
    [root@k8s-master propertirs]# kubectl get configmaps game-config-3 -o yaml
    apiVersion: v1
    data:
      game-special-key: |
        enemies=aliens
        lives=3
        enemies.cheat=true
        enemies.cheat.level=noGoodRotten
        secret.code.passphrase=UUDDLRLRBABAS
        secret.code.allowed=true
        secret.code.lives=30
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T03:33:23Z
      name: game-config-3
      namespace: default
      resourceVersion: "3003678"
      selfLink: /api/v1/namespaces/default/configmaps/game-config-3
      uid: 2345dad3-0de7-11e7-b3d5-fa163ebba51b

### 1.4  指定具体的值 ###

[root@k8s-master propertirs]# kubectl create configmap game-config-4 --from-literal=special.user=zhenyu --from-literal=special.passwd=yaodidiao
    configmap "game-config-4" created
    [root@k8s-master propertirs]# kubectl get configmaps game-config-4 -o yaml
    apiVersion: v1
    data:
      special.passwd: yaodidiao
      special.user: zhenyu
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T03:36:12Z
      name: game-config-4
      namespace: default
      resourceVersion: "3003915"
      selfLink: /api/v1/namespaces/default/configmaps/game-config-4
      uid: 8802f6d2-0de7-11e7-b3d5-fa163ebba51b

## 2、使用ConfigMap ##

### 2.1 环境变量或参数 ###

创建一个Pod，并将一个已经创建好的ConfigMap作为环境变量，注入到Pod中。

[root@k8s-master propertirs]# kubectl get configmaps game-config-4 -o yaml
    apiVersion: v1
    data:
      special.passwd: yaodidiao
      special.user: zhenyu
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T03:36:12Z
      name: game-config-4
      namespace: default
      resourceVersion: "3003915"
      selfLink: /api/v1/namespaces/default/configmaps/game-config-4
      uid: 8802f6d2-0de7-11e7-b3d5-fa163ebba51b
    [root@k8s-master propertirs]# cat testEnv.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        name: testenv
        role: master
      name: testenv
    spec:
      containers:
        - name: testenv
          image: busybox
          imagePullPolicy: IfNotPresent
          env:
            - name: SPECIAL_USER
              valueFrom:
                configMapKeyRef:
                  name: game-config-4
                  key: special.user
          command:
          - sleep
          - "360000"
    [root@k8s-master propertirs]# kubectl create -f testEnv.yaml 
    pod "testenv" created
    [root@k8s-master propertirs]# kubectl exec -ti testenv sh
    / # echo $SPECIAL_USER
    zhenyu
    / #

### 2.2 挂载文件数据卷 ###

[root@k8s-master propertirs]# kubectl get configmaps game-config -o yaml
    apiVersion: v1
    data:
      game.properties: |
        enemies=aliens
        lives=3
        enemies.cheat=true
        enemies.cheat.level=noGoodRotten
        secret.code.passphrase=UUDDLRLRBABAS
        secret.code.allowed=true
        secret.code.lives=30
      ui.properties: |
        color.good=purple
        color.bad=yellow
        allow.textmode=true
        how.nice.to.look=fairlyNice
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T03:22:34Z
      name: game-config
      namespace: default
      resourceVersion: "3002770"
      selfLink: /api/v1/namespaces/default/configmaps/game-config
      uid: a04f90f0-0de5-11e7-b3d5-fa163ebba51b
    [root@k8s-master propertirs]# cat testVolume.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        name: testvolume
        role: master
      name: testvolume
    spec:
      containers:
        - name: testvolume
          image: busybox
          imagePullPolicy: IfNotPresent
          volumeMounts:
          - name: config-volume
            mountPath: /etc/config
          command:
          - sleep
          - "360000"
      volumes:
        - name: config-volume
          configMap:
            name: game-config
    [root@k8s-master propertirs]# kubectl create -f testVolume.yaml 
    pod "testvolume" created
    [root@k8s-master propertirs]# kubectl exec -ti testvolume sh
    / # cd /etc/config/
    /etc/config # ls
    game.properties  ui.properties
    /etc/config # cat game.properties 
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30
    /etc/config # cat ui.properties 
    color.good=purple
    color.bad=yellow
    allow.textmode=true
    how.nice.to.look=fairlyNice
    /etc/config #

### 2.3 挂载信息数据卷 ###

[root@k8s-master propertirs]# cat testVolume.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        name: testvolume
        role: master
      name: testvolume
    spec:
      containers:
        - name: testvolume
          image: busybox
          imagePullPolicy: IfNotPresent
          volumeMounts:
          - name: config-volume
            mountPath: /etc/config
          command:
          - sleep
          - "360000"
      volumes:
        - name: config-volume
          configMap:
            name: game-config-4
    [root@k8s-master propertirs]# kubectl get  configmaps game-config-4 -o yaml
    apiVersion: v1
    data:
      special.passwd: yaodidiao
      special.user: zhenyuyaodidiao
    kind: ConfigMap
    metadata:
      creationTimestamp: 2017-03-21T06:29:29Z
      name: game-config-4
      namespace: default
      resourceVersion: "3018779"
      selfLink: /api/v1/namespaces/default/configmaps/game-config-4
      uid: bd086dca-0dff-11e7-b3d5-fa163ebba51b
    [root@k8s-master propertirs]# kubectl create -f testVolume.yaml 
    pod "testvolume" created
    [root@k8s-master propertirs]# kubectl exec -ti testvolume sh
    / # cd /etc/config/
    /etc/config # ls
    special.passwd  special.user
    /etc/config # cat special.user 
    zhenyuyaodidiao/etc/config # 
    /etc/config # exit

### 2.4 热更新 ###

当ConfigMap以数据卷的形式挂载进Pod的时，这时更新ConfigMap（或删掉重建ConfigMap），Pod内挂载的配置信息会热更新。这时可以增加一些监测配置文件变更的脚本，然后reload对应服务。

[Kubernetes_ConfigMap]: https://www.cnblogs.com/zhenyuyaodidiao/p/6594410.html