ConfigMap概述
configmap用于将应用所需的配置信息与程序进行分离, 使应用程序更好的复用, 在大规模容器集群环境中, 对应用进行统一配置管理.
一般应用场景:
- 生成为容器内的环境变量;
- 以Volume的形式挂载为容器内部的文件或目录.
configmap以一个或多个key:value的形式保存在kubernetes系统中供应用使用, 既可以用于表示一个变量的值(例如log-level:info), 也可以用于表示一个完整的配置文件内容(例如xml或properties配置文件的全部内容).
声明方式:
- 使用yaml配置文件;
- 使用命令行命令(kubectl create configmap).
Pod中使用方式:
创建ConfigMap
1. 使用yaml文件方式创建
1) 内容为变量
创建yaml文件cm-log-test.yaml:
apiVersion: v1kind: ConfigMapmetadata: name: cm-logdata: apploglevel: info appdatadir: /var/data
生成configmap:
[root@localhost pod_dir]# kubectl create -f cm-log-test.yamlconfigmap "cm-log" created
2) 内容为配置文件内容
创建yaml文件cm-file-test.yaml:
apiVersion: v1kind: ConfigMapmetadata: name: cm-filedata: key-serverxml: | key-loggingproperties: | jdbc.driverClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/ku8manage?useUnicode=true&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai jdbc.username=root jdbc.password=****** https=true web.uri=http://localhost:8080 web.session.expireTime=1200
生成configmap:
[root@localhost pod_dir]# kubectl create -f cm-file-test.yamlconfigmap "cm-file" created
2. 使用命令行方式创建
1) 字面值创建
使用--from-literal按字面值创建, 每个--from-literal后跟一个键值对.
# 语法kubectl create configmap --from-literal=key1=value1 --from-literal=key2=value2
[root@localhost pod_dir]# kubectl create configmap cm-literal --from-literal=loglevel=info --from-literal=datadir=/var/dataconfigmap "cm-literal" created
验证
[root@localhost pod_dir]# kubectl get configmap cm-literal -o yamlapiVersion: v1data: datadir: /var/data loglevel: infokind: ConfigMapmetadata: creationTimestamp: 2018-07-05T11:29:55Z name: cm-literal namespace: default resourceVersion: "29156" selfLink: /api/v1/namespaces/default/configmaps/cm-literal uid: bdfe61f9-8046-11e8-b599-000c2964ecfc
2) 文件创建
使用--from-file按文件创建, 每个--from-file后跟一个文件路径, 也可以指定key名称, 可选.
# 语法kubectl create configmap --from-file=[key=]file-path-1 --from-file=[key=]file-path-2
[root@localhost pod_dir]# kubectl create configmap cm-file --from-file=./server.xml --from-file=./log.properties configmap "cm-file" created
验证
[root@localhost pod_dir]# kubectl describe configmaps cm-file Name: cm-fileNamespace: defaultLabels: Annotations: Data====log.properties:----verClassName=com.mysql.jdbc.Driver...server.xml:----ns xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance...
3) 目录创建
使用--from-literal按字面值创建, --from-file后跟一个目录, 该目录下的每个配置文件名都会被设置为key, 文件的内容被设置为value.
# 语法kubectl create configmap --from-file=config-file-dir
[root@localhost pod_dir]# kubectl create configmap cm-dir --from-file=./config-dir/configmap "cm-dir" created
验证
[root@localhost pod_dir]# kubectl describe configmap cm-dir Name: cm-dirNamespace: defaultLabels: Annotations: Data====log.properties:----verClassName=com.mysql.jdbc.Driver...server.xml:----ns xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance...
在Pod中使用ConfigMap
1. 环境变量方式
以前面创建的创cm-log为例:
apiVersion: v1kind: ConfigMapmetadata: name: cm-logdata: apploglevel: info appdatadir: /var/data
定义pod的yaml文件pod-cm-test.yaml:
apiVersion: v1kind: Podmetadata: name: cm-test-pod labels: name: cm-pod-labelspec: containers: - name: cm-test image: busybox command: ["/bin/sh", "-c", "env | grep APP"] env: - name: APPLOGLEVEL #定义环境变量名称 valueFrom: configMapKeyRef: name: cm-log #环境变量的值取自cm-log key: apploglevel #取key apploglevel对应的值 - name: APPDATADIR valueFrom: configMapKeyRef: name: cm-log key: appdatadir restartPolicy: Never
创建Pod:
[root@localhost pod_dir]# kubectl create -f pod-cm-test.yamlpod "cm-test-pod" created
验证:
[root@localhost pod_dir]# kubectl logs cm-test-pod APPDATADIR=/var/dataAPPLOGLEVEL=info
上面用到了valueFrom, 用于指定单个环境变量情况, 还有envFrom, 可以将指定ConfigMap中的所有键值自动生成环境变量, 环境变量名称就是key, 环境变量的值就是value. 如下:
apiVersion: v1kind: Podmetadata: name: cm-test-pod labels: name: cm-pod-labelspec: containers: - name: cm-test image: busybox command: ["/bin/sh", "-c", "env"] envFrom: - configMapRef: name: cm-log restartPolicy: Never
创建Pod:
[root@localhost pod_dir]# kubectl create -f pod-test-envFrom.yaml pod "cm-test-pod" created
验证:
[root@localhost pod_dir]# kubectl logs cm-test-pod apploglevel=infoKUBERNETES_PORT=tcp://10.68.0.1:443KUBERNETES_PORT_443_TCP_PROTO=tcpappdatadir=/var/dataKUBERNETES_PORT_443_TCP=tcp://10.68.0.1:443PWD=/
2. Volume挂载
使用上边以cm-file-test.yaml创建的cm-file为例.
创建Pod:
apiVersion: v1kind: Podmetadata: name: cm-test-volumespec: containers: - name: cm-test-volume image: kubeguide/tomcat-app:v1 ports: - containerPort: 8080 volumeMounts: - name: server mountPath: /configfiles volumes: - name: server configMap: name: cm-file items: - key: key-serverxml path: server.xml - key: key-properties path: logging.properties
创建Pod:
[root@localhost pod_dir]# kubectl create -f pod-volume-test.yaml pod "cm-test-volume" created
验证:
登录容器, 查看configfiles目录下存在server.xml和logging.properties文件:
[root@localhost pod_dir]# kubectl exec -ti cm-test-volume -- bashroot@cm-test-volume:/usr/local/tomcat# cd /configfiles/root@cm-test-volume:/configfiles# ls -a. .. ..2018_07_05_13_14_04.531049961 ..data logging.properties server.xml
查看文件内容:
root@cm-test-volume:/configfiles# cat logging.properties verClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/ku8manage?useUnicode=true&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai...root@cm-test-volume:/configfiles# cat logging.properties verClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/ku8manage?useUnicode=true&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai jdbc.username=root jdbc.password=****** https=true web.uri=http://localhost:8080 web.session.expireTime=1200root@cm-test-volume:/configfiles# cat server.xml ns xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" http://www.springframework.org/schema/task/spring-task.xsd">...
如果在引用ConfigMap时不指定items, 则使用volumeMount方式在容器内的目录中为每个item生成一个文件名为key的文件, 如下:
创建Pod:
apiVersion: v1kind: Podmetadata: name: cm-test-volumespec: containers: - name: cm-test-volume image: kubeguide/tomcat-app:v1 ports: - containerPort: 8080 volumeMounts: - name: server mountPath: /configfiles volumes: - name: server configMap: name: cm-file
应用: 使用ConfigMap配置redis
创建ConfigMap:
[root@localhost pod_dir]# kubectl create configmap example-redis-config --from-file=./redis-config configmap "example-redis-config" created
redis-config文件内容如下:
maxmemory 2mbmaxmemory-policy allkeys-lru
查看已创建的配置ConfigMap:
[root@localhost pod_dir]# kubectl get configmap example-redis-config -o yamlapiVersion: v1data: redis-config: | maxmemory 2mb maxmemory-policy allkeys-lrukind: ConfigMapmetadata: creationTimestamp: 2018-07-06T02:03:56Z name: example-redis-config namespace: default resourceVersion: "41583" selfLink: /api/v1/namespaces/default/configmaps/example-redis-config uid: d6fa0d84-80c0-11e8-b599-000c2964ecfc
创建pod yaml文件:
apiVersion: v1kind: Podmetadata: name: redisspec: containers: - name: redis image: kubernetes/redis:v1 env: - name: MASTER value: "true" ports: - containerPort: 6379 resources: limits: cpu: "0.1" volumeMounts: - mountPath: /redis-master-data name: data - mountPath: /redis-master name: config volumes: - name: data emptyDir: {} - name: config configMap: name: example-redis-config items: - key: redis-config path: redis.conf 创建pod:
[root@localhost pod_dir]# kubectl create -f pod-cm-redis-test.yaml pod "redis" created
验证:
进入容器查看
[root@localhost pod_dir]# kubectl exec -it redis redis-cli127.0.0.1:6379> CONFIG GET maxmemory1) "maxmemory"2) "2097152"127.0.0.1:6379> config get maxmemory-policy1) "maxmemory-policy"2) "allkeys-lru"
使用ConfigMap须知:
- ConfigMap必须在pod创建之前创建;
- ConfigMap受Namespace限制, 处于同一Namespace的pod才能引用到它;
- kubelet只支持被API server管理的pod使用ConfigMap, 也就是说静态pod不能使用ConfigMap.