Kubernetes 第十二章 ConfigMap

ConfigMap

ConfigMap用于保存配置数据的键值对，可以用来保存单个属性，也可以用来保存配置文件。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。

ConfigMap创建

可以使用kubectl create configmap从文件、目录或者key-value字符串创建等创建ConfigMap。

以使用kubectl create configmap从文件、目录或者key-value字符串创建等创建ConfigMap。

# 从key-value字符串创建ConfigMap
$ kubectl create configmap special-config --from-literal=special.how=very
configmap "special-config" created
$ kubectl get configmap special-config -o go-template='{{.data}}'
map[special.how:very]

# 从env文件创建
$ echo -e "a=b
c=d" | tee config.env
a=b
c=d
$ kubectl create configmap special-config --from-env-file=config.env
configmap "special-config" created
$ kubectl get configmap special-config -o go-template='{{.data}}'
map[a:b c:d]

# 从目录创建
$ mkdir config
$ echo a>config/a
$ echo b>config/b
$ kubectl create configmap special-config --from-file=config/
configmap "special-config" created
$ kubectl get configmap special-config -o go-template='{{.data}}'
map[a:a
 b:b
]

ConfigMap使用

ConfigMap可以通过多种方式在Pod中使用，比如设置环境变量、设置容器命令行参数、在Volume中创建配置文件等。

注意

ConfigMap必须在Pod引用它之前创建
使用envFrom时，将会自动忽略无效的键
Pod只能使用同一个命名空间内的ConfigMap

apiVersion: v1
kind: Pod
metadata:
  name: test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: [ "/bin/sh", "-c", "env" ]
      env:
        - name: SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
              name: special-config
              key: special.how
        - name: SPECIAL_TYPE_KEY
          valueFrom:
            configMapKeyRef:
              name: special-config
              key: special.type
      envFrom:
        - configMapRef:
            name: env-config
  restartPolicy: Never

[root@kube configMap]# kubectl log test-pod
log is DEPRECATED and will be removed in a future version. Use logs instead.
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_SERVICE_PORT=443
HOSTNAME=test-pod
MY_SVC_SERVICE_PORT=80
MY_SVC_PORT=tcp://10.96.31.10:80
SHLVL=1
HOME=/root
MY_SVC_PORT_80_TCP_ADDR=10.96.31.10
SPECIAL_TYPE_KEY=charm
MY_SVC_PORT_80_TCP_PORT=80
MY_SVC_PORT_80_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
KUBERNETES_PORT_443_TCP_PORT=443
MY_SVC_PORT_80_TCP=tcp://10.96.31.10:80
KUBERNETES_PORT_443_TCP_PROTO=tcp
SPECIAL_LEVEL_KEY=very
log_level=INFO
MY_SVC_SERVICE_PORT_HTTP=80
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_SERVICE_HOST=10.96.0.1
PWD=/
MY_SVC_SERVICE_HOST=10.96.31.10
[root@kube configMap]# 

用作命令行参数

将ConfigMap用作命令行参数时，需要先把ConfigMap的数据保存在环境变量中，然后通过$(VAR_NAME)的方式引用环境变量.

apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: [ "/bin/sh", "-c", "echo $(SPECIAL_LEVEL_KEY) $(SPECIAL_TYPE_KEY)" ]
      env:
        - name: SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
              name: special-config
              key: special.how
        - name: SPECIAL_TYPE_KEY
          valueFrom:
            configMapKeyRef:
              name: special-config
              key: special.type
  restartPolicy: Never

[root@kube configMap]# kubectl logs  dapi-test-pod
very charm
[root@kube configMap]# 

使用volume将ConfigMap作为文件或目录直接挂载

将创建的ConfigMap直接挂载至Pod的/etc/config目录下，其中每一个key-value键值对都会生成一个文件，key为文件名，value为内容

apiVersion: v1
kind: Pod
metadata:
  name: vol-test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: [ "/bin/sh", "-c", "cat /etc/config/special.how" ]
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: special-config
  restartPolicy: Never

[root@kube configMap]# kubectl logs vol-test-pod
very
[root@kube configMap]# 
[root@kube configMap]# 

 将创建的ConfigMap中special.how这个key挂载到/etc/config目录下的一个相对路径/keys/special.level。如果存在同名文件，直接覆盖。其他的key不挂载

apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: gcr.io/google_containers/busybox
      command: [ "/bin/sh","-c","cat /etc/config/keys/special.level" ]
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: special-config
        items:
        - key: special.how
          path: keys/special.level
  restartPolicy: Never