kubernetes系列之ConfigMap使用方式

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作用理解

核心用途就是容器和配置的分离解耦。

如启用一个mysql容器，mysql容器重要的文件有两部分,一部分为存储数据文件,一部分为配置文件my.cnf，存储数据可以用持久存储实现和容器的分离解耦，配置文件也能够实现和容器的分离解耦,也就是说mysql容器能够直接读取并使用预先配置好的配置文件(而不是使用容器中默认自带的配置文件).这就是configMap的功能。

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。

创建ConfigMap有两种方式

通过yaml文件创建

通过kubectl create创建

示例

命令行创建

# 方式一： [root@master-01 configmap]# kubectl create cm mysql-config --from-file=mysqld.cnf configmap/mysql-config created [root@master-01 configmap]# kubectl describe cm mysql-config Name: mysql-config Namespace: default Labels: <none> Annotations: <none> Data ==== mysqld.cnf: ---- [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysql] no-auto-rehash [mysqld] user = mysql port = 3306 socket = /var/run/mysqld/mysqld.sock datadir = /var/lib/mysql [mysqld_safe] log-error= /var/log/mysql/mysql_oldboy.err pid-file = /var/run/mysqld/mysqld.pid Events: <none> # 方式二： [root@master-01 configmap]# kubectl create configmap env-config --from-literal=log_level=INFO # 以key：value的形式创建

yaml文件创建

[root@master-01 configmap]# cat my-config.yaml apiVersion: v1 kind: ConfigMap metadata: name: mysql-config2 data: mysqld.cnf: | [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysql] no-auto-rehash [mysqld] user = mysql port = 3306 socket = /var/run/mysqld/mysqld.sock datadir = /var/lib/mysql [mysqld_safe] log-error= /var/log/mysql/mysql_oldboy.err pid-file = /var/run/mysqld/mysqld.pid [root@master-01 configmap]# kubectl apply -f my-config.yaml configmap/mysql-config2 created [root@master-01 configmap]# kubectl describe cm mysql-config2 Name: mysql-config2 Namespace: default Labels: <none> Annotations: kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"v1","data":{"mysqld.cnf":"[client]\nport = 3306\nsocket = /var/run/mysqld/mysqld.sock\n[mysql]\nno-auto-rehash\n\n[mysqld]\... Data ==== mysqld.cnf: ---- [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysql] no-auto-rehash [mysqld] user = mysql port = 3306 socket = /var/run/mysqld/mysqld.sock datadir = /var/lib/mysql [mysqld_safe] log-error= /var/log/mysql/mysql_oldboy.err pid-file = /var/run/mysqld/mysqld.pid Events: <none>

ConfigMap 使用

ConfigMap 可以通过三种方式在 Pod 中使用

1.环境变量方式

2.volume挂载方式(一般都是用这个,支持热更新）

3.设置容器命令行参数

用环境变量

[root@master-01 configmap]# kubectl create configmap env-config --from-literal=log_level=INFO configmap/env-config created [root@master-01 configmap]# kubectl create configmap special-config --from-literal=special.how=very --from-literal=special.type=charm configmap/special-config created

编排

[root@master-01 configmap]# cat bu.yaml apiVersion: v1 kind: Pod metadata: name: test-pod spec: containers: - name: test-container image: 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@master-01 configmap]# kubectl apply -f bu.yaml pod/test-pod created

查看日志可以发现,环境变量注入到了容器中了

[root@master-01 configmap]# kubectl logs test-pod ... SPECIAL_TYPE_KEY=charm SPECIAL_LEVEL_KEY=very log_level=INFO

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.

编排

apiVersion: v1 kind: Pod metadata: name: dapi-test-pod spec: containers: - name: test-container image: busybox command: ["/bin/sh", "-c", "echo $(SPECIAL_LEVEL_KEY) $(SPECIAL_TYPE_KEY)" ] ...

查看日志可以看到环境变量被输出

[root@master-01 configmap]# kubectl logs dapi-test-pod very charm

volume挂载方式（支持动态更新）

configmap 挂载文件时，会先覆盖掉挂载目录，然后再将 congfigmap 中的内容作为文件挂载进行。如果想不对原来的文件夹下的文件造成覆盖，只是将 configmap 中的每个 key，按照文件的方式挂载到目录下，可以使用 subpath 参数。

实战例子

编排

[root@master-01 configmap]# cat mysql-d.yaml apiVersion: v1 kind: ConfigMap metadata: name: myconfig data: v1: Abc1234!@# --- apiVersion: v1 kind: Service metadata: name: mysql-t spec: ports: - port: 3306 selector: app: mysql-t --- apiVersion: apps/v1beta1 kind: Deployment metadata: name: mysql-t spec: selector: matchLabels: app: mysql-t template: metadata: labels: app: mysql-t spec: containers: - image: mysql:5.7 name: mysql-t ports: - containerPort: 3306 env: - name: MYSQL_ROOT_PASSWORD valueFrom: configMapKeyRef: name: my-config key: v2 volumeMounts: - name: mysql-t1 mountPath: /etc/mysql/mysql.conf.d volumes: - name: mysql-t1 configMap: name: mysql-config2 [root@master-01 configmap]# kubectl apply -f mysql-d.yaml configmap/myconfig created service/mysql-t created deployment.apps/mysql-t created

volumeMounts/mountPath: 容器里挂载的目录，这个目录其实很重要,你要使用个容器的应用,需熟悉这个应用的配置文件存放目录并且挂载到正确目录.挂载目录错了容器应用无法读取到配置文件。

volumes：定义使用的卷

name: mysql-t1 注意volumes和volumeMounts的name是相对应的.

进入mysql容器中测试，可以看到读取的就是congfigmap,密码已经生效.

[root@master-01 configmap]# kubectl exec -ti mysql-t-7bb6cbbf77-xqfc2 bash root@mysql-t-7bb6cbbf77-xqfc2:/# mysql -uroot -pAbc1234\!\@\# mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.7.25 MySQL Community Server (GPL) Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>

查看pod详情

[root@master-01 configmap]# kubectl describe pod mysql-t-7bb6cbbf77-xqfc2 Name: mysql-t-7bb6cbbf77-xqfc2 Namespace: default Priority: 0 PriorityClassName: <none> Node: 192.168.209.131/192.168.209.131 Start Time: Tue, 02 Apr 2019 10:29:05 +0800 Labels: app=mysql-t pod-template-hash=7bb6cbbf77 Annotations: <none> Status: Running IP: 172.17.12.3 Controlled By: ReplicaSet/mysql-t-7bb6cbbf77 Containers: mysql-t: Container ID: docker://58d61cddb16b6cd14593d7e4d1bc12c6157e7d9c28ffa25c3d3e8a571867bb71 Image: mysql:5.7 Image ID: docker-pullable://mysql@sha256:dba5fed182e64064b688ccd22b2f9cad4ee88608c82f8cff21e17bab8da72b81 Port: 3306/TCP Host Port: 0/TCP State: Running Started: Tue, 02 Apr 2019 10:29:06 +0800 Ready: True Restart Count: 0 Environment: MYSQL_ROOT_PASSWORD: <set to the key 'v1' of config map 'myconfig'> Optional: false Mounts: /etc/mysql/mysql.conf.d from mysql-t1 (rw) /var/run/secrets/kubernetes.io/serviceaccount from default-token-tb5bg (ro) Conditions: Type Status Initialized True Ready True ContainersReady True PodScheduled True Volumes: mysql-t1: Type: ConfigMap (a volume populated by a ConfigMap) Name: mysql-config2 Optional: false default-token-tb5bg: Type: Secret (a volume populated by a Secret) SecretName: default-token-tb5bg Optional: false QoS Class: BestEffort Node-Selectors: <none> Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s node.kubernetes.io/unreachable:NoExecute for 300s Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 3m32s default-scheduler Successfully assigned default/mysql-t-7bb6cbbf77-xqfc2 to 192.168.209.131 Normal Pulled 3m31s kubelet, 192.168.209.131 Container image "mysql:5.7" already present on machine Normal Created 3m31s kubelet, 192.168.209.131 Created container Normal Started 3m31s kubelet, 192.168.209.131 Started container

configmap配置段为

Environment: MYSQL_ROOT_PASSWORD: <set to the key 'v1' of config map 'myconfig'> Optional: false Mounts: /etc/mysql/mysql.conf.d from mysql-t1 (rw)

热更新测试

修改my-cnfig2，使用edit命令

在[mysqld]段添加如下配置

server-id=1

查看my-cnfig2信息

[root@master-01 configmap]# kubectl describe cm mysql-config2 ... mysqld.cnf: ---- [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysql] no-auto-rehash [mysqld] user = mysql port = 3306 socket = /var/run/mysqld/mysqld.sock datadir = /var/lib/mysql server-id=1 [mysqld_safe] log-error= /var/log/mysql/mysql_oldboy.err pid-file = /var/run/mysqld/mysqld.pid Events: <none>

进mysql容器查看

[root@master-01 configmap]# kubectl edit cm mysql-config2 configmap/mysql-config2 edited [root@master-01 configmap]# kubectl exec -ti mysql-t-7bb6cbbf77-xqfc2 bash root@mysql-t-7bb6cbbf77-xqfc2:/# cat /etc/mysql/mysql.conf.d/mysqld.cnf [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysql] no-auto-rehash [mysqld] user = mysql port = 3306 socket = /var/run/mysqld/mysqld.sock datadir = /var/lib/mysql server-id=1 [mysqld_safe] log-error= /var/log/mysql/mysql_oldboy.err pid-file = /var/run/mysqld/mysqld.pid root@mysql-t-7bb6cbbf77-xqfc2:/#