ConfigMap 描述信息

ConfigMap 功能在 Kubernetes 1.2 版本中引入，许多应用程序会从配置文件、命令行参数或环境变量中读取配置信息。ConfigMap API 给我们提供了向容器中注入配置信息的机制，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 创建

Ⅰ、使用目录创建

  1. $ mkdir -p /root/configmap/dir/
  1. cat <<EOF >/root/configmap/dir/game.properties
  2. enemies=aliens
  3. lives=3
  4. enemies.cheat=true
  5. enemies.cheat.level=noGoodRotten
  6. secret.code.passphrase=UUDDLRLRBABAS
  7. secret.code.allowed=true
  8. secret.code.lives=30
  9. EOF
  1. cat <<EOF >/root/configmap/dir/ui.properties
  2. color.good=purple
  3. color.bad=yellow
  4. allow.textmode=true
  5. how.nice.to.look=fairlyNice
  6. EOF
  1. $ ls /root/configmap/dir/
  2. game.properties  
  3. ui.properties
  1. $ kubectl create configmap game-config --from-file=/root/configmap/dir/
  2. configmap/game-config created
  4. $ kubectl get configmap
  6. $ kubectl get cm game-config -o yaml

--from-file 指定在目录下的所有文件都会被用在 ConfigMap 里面创建一个键值对，键的名字就是文件名，值就是文件的内容

Ⅱ、使用文件创建

  1.           <br />只要指定为一个文件就可以从单个文件中创建 ConfigMap
  1. $ kubectl create configmap game-config-2 --from-file=/root/configmap/dir/game.properties
  2. configmap/game-config-2 created
  4. $ kubectl get configmaps game-config-2 -o yaml

--from-file 这个参数可以使用多次，你可以使用两次分别指定上个实例中的那两个配置文件，效果就跟指定整个目录是一样的

Ⅲ、使用字面值创建

使用文字值创建，利用 --from-literal 参数传递配置信息，该参数可以使用多次，格式如下

  1. $ kubectl create configmap special-config \
  2.   --from-literal=special.how=very \
  3.   --from-literal=special.type=charm
  4. configmap/special-config created
  6. $ kubectl get configmaps special-config -o yaml

Pod 中使用 ConfigMap

Ⅰ、使用 ConfigMap 来替代环境变量

  1. cat <<EOF >/root/configmap/env/special-config.yaml
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: special-config
  6.   namespace: default
  7. data:
  8.   special.how: very
  9.   special.type: charm
  10. EOF
  1. cat <<EOF >/root/configmap/env/env-config.yaml
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: env-config
  6.   namespace: default
  7. data:
  8.   log_level: INFO
  9. EOF
  1. cat <<EOF >/root/configmap/env/pod.yaml
  2. apiVersion: v1
  3. kind: Pod
  4. metadata:
  5.   name: dapi-test-pod
  6. spec:
  7.   containers:
  8.     - name: test-container
  9.       image: hub.yangguoxiang.com/library/myapp:v1.0
  10.       command: [ "/bin/sh", "-c", "env" ]
  11.       env:
  12.         - name: SPECIAL_LEVEL_KEY
  13.           valueFrom:
  14.             configMapKeyRef:
  15.               name: special-config
  16.               key: special.how
  17.         - name: SPECIAL_TYPE_KEY
  18.           valueFrom:
  19.             configMapKeyRef:
  20.               name: special-config
  21.               key: special.type
  22.       envFrom:
  23.         - configMapRef:
  24.             name: env-config
  25.   restartPolicy: Never
  26. EOF
  1. $ kubectl apply -f env-config.yaml 
  2. configmap/env-config created
  4. $ kubectl create -f pod.yaml 
  5. pod/dapi-test-pod created
  7. $ kubectl log pod/dapi-test-pod
  8. $ kubectl log pod/dapi-test-pod | grep TYPE

Ⅱ、用 ConfigMap 设置命令行参数

  1. cat <<EOF >/root/configmap/env/special-config.yaml
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: special-config
  6.   namespace: default
  7. data:
  8.   special.how: very
  9.   special.type: charm
  10. EOF
  1. cat <<EOF >/root/configmap/env/pod_print.yaml
  2. apiVersion: v1
  3. kind: Pod
  4. metadata:
  5.   name: dapi-test-pod-print
  6. spec:
  7.   containers:
  8.     - name: test-container
  9.       image: hub.yangguoxiang.com/library/myapp:v1.0
  10.       command: [ "/bin/sh", "-c", "echo \$(SPECIAL_LEVEL_KEY) \$(SPECIAL_TYPE_KEY)" ]
  11.       env:
  12.         - name: SPECIAL_LEVEL_KEY
  13.           valueFrom:
  14.             configMapKeyRef:
  15.               name: special-config
  16.               key: special.how
  17.         - name: SPECIAL_TYPE_KEY
  18.           valueFrom:
  19.             configMapKeyRef:
  20.               name: special-config
  21.               key: special.type
  22.   restartPolicy: Never
  23. EOF
  1. $ kubectl create -f /root/configmap/env/pod_print.yaml
  2. pod/dapi-test-pod-print created
  4. $ kubectl log pod/dapi-test-pod-print

Ⅲ、通过数据卷插件使用ConfigMap

  1. cat <<EOF >/root/configmap/env/special-config.yaml
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: special-config
  6.   namespace: default
  7. data:
  8.   special.how: very
  9.   special.type: charm
  10. EOF

在数据卷里面使用这个 ConfigMap ，有不同的选项。最基本的就是将文件填入数据卷，在这个文件中，键就是文件名，键值就是文件内容

  1. cat <<EOF >/root/configmap/env/pod_print2.yaml
  2. apiVersion: v1
  3. kind: Pod
  4. metadata:
  5.   name: dapi-test-pod-print2
  6. spec:
  7.   containers:
  8.     - name: test-container
  9.       image: hub.yangguoxiang.com/library/myapp:v1.0
  10.       command: [ "/bin/sh", "-c", "cat /etc/config/special.how" ]
  11.       volumeMounts:
  12.       - name: config-volume
  13.         mountPath: /etc/config
  14.   volumes:
  15.     - name: config-volume
  16.       configMap:
  17.         name: special-config
  18.   restartPolicy: Never
  19. EOF
  1. $ kubectl create -f /root/configmap/env/pod_print2.yaml
  2. pod/dapi-test-pod-print2 created
  4. $ kubectl logs pod/dapi-test-pod-print2
  5. very

ConfigMap 的热更新

  1. cat <<EOF >/root/configmap/env/cm_pod.yaml
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: log-config
  6.   namespace: default
  7. data:
  8.   log_level: INFO
  9. ---
  10. apiVersion: extensions/v1beta1
  11. kind: Deployment
  12. metadata:
  13.   name: my-nginx
  14. spec:
  15.   replicas: 1
  16.   template:
  17.     metadata:
  18.       labels:
  19.         run: my-nginx
  20.     spec:
  21.       containers:
  22.       - name: my-nginx
  23.         image: hub.yangguoxiang.com/library/myapp:v1.0
  24.         ports:
  25.         - containerPort: 80
  26.         volumeMounts:
  27.         - name: config-volume
  28.           mountPath: /etc/config
  29.       volumes:
  30.         - name: config-volume
  31.           configMap:
  32.             name: log-config
  33. EOF
  1. $ kubectl apply -f cm_pod.yaml 
  2. configmap/log-config created
  3. deployment.extensions/my-nginx created
  5. $ kubectl exec my-nginx-b748cbcc9-sn4jg -it -- cat /etc/config/log_level
  6. INFO
  7. # # 或者
  8. $ kubectl exec `kubectl get pods -l run=my-nginx  -o=name|cut -d "/" -f2` cat /etc/config/log_level
  9. INFO

修改 ConfigMap

  1. $ kubectl edit configmap log-config

修改 **log_level** 的值为 **DEBUG** 等待大概 10 秒钟时间，再次查看环境变量的值

  1. $ kubectl exec `kubectl get pods -l run=my-nginx  -o=name|cut -d "/" -f2` cat /etc/config/log_level
  2. DEBUG

ConfigMap 更新后滚动更新 Pod

更新 ConfigMap 目前并不会触发相关 Pod 的滚动更新，可以通过修改 pod annotations 的方式强制触发滚动更新

  1. $ kubectl patch deployment my-nginx \
  2. --patch '{"spec": {"template": {"metadata": {"annotations": {"version/config": "20190411" }}}}}'

这个例子里我们在 .spec.template.metadata.annotations 中添加 version/config ，每次通过修改
version/config 来触发滚动更新

！！！ 更新 ConfigMap 后：
使用该 ConfigMap 挂载的 Env 不会同步更新
使用该 ConfigMap 挂载的 Volume 中的数据需要一段时间（实测大概10秒）才能同步更新