配置文件之ConfigMap

一、ConfigMap概述

1)ConfigMap 是一种 API 对象，用来将非机密性的数据保存到键值对中。使用时， Pods 可以将其用作环境变量、命令行参数或者存储卷中的配置文件。
2)ConfigMap 将您的环境配置信息和容器镜像解耦，便于应用配置的修改，ConfigMap组件可以很好的帮助我们实现应用和配置分离，避免因为修改配置项而重新构建镜像。
3)ConfigMap跟Secret很类似，但它可以更方便地处理不包含敏感信息的字符串。

二、创建configmap

[root@master-191 ~]# vim configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: you-config
  namespace: default
data:
  special.level: first
  special.type: happy

[root@master-191 ~]# kubectl create -f configmap.yaml 
configmap "you-config" created
[root@master-191 ~]# kubectl get cm
NAME         DATA      AGE
you-config   2         6s

三、引用configmap文件

1）变量方式

[root@master-191 ~]# vim config-var.yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
    - name: busybox
      image: busybox
      command: [ "/bin/sh", "-c", "echo $(LEVEL) $(TYPE)" ]
      env:
        - name: LEVEL
          valueFrom:
            configMapKeyRef:
              name: you-config
              key: special.level
        - name: TYPE
          valueFrom:
            configMapKeyRef:
              name: you-config
              key: special.type
  restartPolicy: Never

[root@master-191 ~]# kubectl create -f config-var.yaml 
pod "mypod" created
[root@master-191 ~]# kubectl get pod
NAME      READY     STATUS              RESTARTS   AGE
mypod     0/1       ContainerCreating   0          3s
[root@master-191 ~]# kubectl get pod
No resources found, use --show-all to see completed objects.
[root@master-191 ~]# kubectl logs -f mypod
first happy

2)volume挂载方式
ConfigMap 支持同一个目录下挂载多个 key 和多个目录。例如下面将 special.level 和 special.type 挂载到 / etc/config 下。并且将 special.how 同时挂载到 / etc/config2 下。

[root@master-191 ~]# vim config-vol.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: qing-pod
spec:
  containers:
    - name: test-container
      image: busybox
      command: ["/bin/sh","-c","sleep 36000"]
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
      - name: config-volume2
        mountPath: /etc/config2
  volumes:
    - name: config-volume
      configMap:
        name: you-config
        items:
        - key: special.level
          path: keys/special.level
        - key: special.type
          path: keys/special.type
    - name: config-volume2
      configMap:
        name: you-config
        items:
        - key: special.level
          path: keys/special.level
  restartPolicy: Never

[root@master-191 ~]# kubectl create -f config-vol.yaml 
pod "qing-pod" created
[root@master-191 ~]# kubectl get pod
NAME       READY     STATUS              RESTARTS   AGE
qing-pod   1/1       Running             0          4s
[root@master-191 ~]# kubectl exec -it qing-pod sh
/ # ls /etc/
config       config2      group        hostname     hosts        localtime    mtab         network      passwd       resolv.conf  shadow
/ # ls /etc/config
keys
/ # ls /etc/config2
keys
/ # ls /etc/config/keys/
special.level  special.type
/ # ls /etc/config2/keys/
special.level
/ # cat /etc/config2/keys/special.level 
first/ # 

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