kubernetes之配置mysql的configmap

一.简单说明

我们在运行一个mysql服务时，mysql服务有两类重要的数据，一个是存储的数据、另一个是存储的配置文件。存储数据这里我们可以使用挂载PVC来实现持久化存储，配置文件这里我们如果实现和容器的解耦，可以采用configmap来实现。

二.ConfigMap介绍

2.1 ConfigMap作用和使用场景

• ConfigMap用于保存配置数据，以键值对的形式存储
• ConfigMap资源提供了向Pod注入配置数据的方法
• ConfigMap旨在让镜像与配置文件解耦，以实现镜像的可移植性和可复用性。
• 填充环境变量的值
• 填充卷的配置文件

2.2 ConfigMap的创建

这里有以下几种创建方式：

• 使用字面值创建

  kubectl create configmap my-configmap --from-literal=key1=1 --from-literal=key2=2
  [root@k8s001 ~]# kubectl get cm my-configmap -o yaml
  apiVersion: v1
  data:
    key1: "1"
    key2: "2"
  kind: ConfigMap
  metadata:
    creationTimestamp: "2020-08-11T03:54:00Z"
    name: my-configmap
    namespace: default
    resourceVersion: "4745970"
    selfLink: /api/v1/namespaces/default/configmaps/my-configmap
    uid: 4a277575-db86-11ea-bb5f-6c4b9005d934
  

• 使用文件创建

  [root@k8s001 ~]# cat configmap-file
  10.10.2.2 k8s001
  [root@k8s001 ~]# kubectl create cm my-configmap-file --from-file=configmap-file
  configmap/my-configmap-file created
  [root@k8s001 ~]# kubectl get cm my-configmap-file -o yaml
  apiVersion: v1
  data:
    configmap-file: |
      10.10.2.2 k8s001
  kind: ConfigMap
  metadata:
    creationTimestamp: "2020-08-11T03:58:23Z"
    name: my-configmap-file
    namespace: default
    resourceVersion: "4747102"
    selfLink: /api/v1/namespaces/default/configmaps/my-configmap-file
    uid: e6c966b8-db86-11ea-bb5f-6c4b9005d934
  

• 使用目录创建

  [root@k8s001 ~]# mkdir configmap-dir
  [root@k8s001 ~]# cp configmap-file ./configmap-dir/
  [root@k8s001 ~]# kubectl create cm myconfigmap-dir --from-file=configmap-dir
  configmap/myconfigmap-dir created
  [root@k8s001 ~]# kubectl get cm myconfigmap-dir -o yaml
  apiVersion: v1
  data:
    configmap-file: |
      10.10.2.2 k8s001
  kind: ConfigMap
  metadata:
    creationTimestamp: "2020-08-11T04:01:51Z"
    name: myconfigmap-dir
    namespace: default
    resourceVersion: "4748006"
    selfLink: /api/v1/namespaces/default/configmaps/myconfigmap-dir
    uid: 62fde3bb-db87-11ea-ab20-6c4b9005ca34
  

• 编写ConfigMap的yaml文件来创建

  [root@k8s001 ~]# cat configmap_mysql.yaml
  apiVersion: v1
  kind: ConfigMap
  metadata:
    name: mysql-config
    namespace: business
  data:
    mysqld.cnf: |-
      [mysqld]
      pid-file	= /var/run/mysqld/mysqld.pid
      socket      = /var/run/mysqld/mysqld.sock
      datadir	= /var/lib/mysql
      symbolic-links = 0
      max_allowed_packet = 50M
      character_set_server = utf8
      collation_server = utf8_general_ci
      group_concat_max_len = 102400
      [client]
      default_character_set = utf8
  

2.3 如何使用ConfigMap

• 可以通过环境变量的形式直接传递给Pod

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: wf-mysql
spec:
  containers:
  - image: mysql:5.7
    imagePullPolicy: IfNotPresent
    name: mysql
    env:
    - name: MYSQL_ROOT_PASSWORD
      valueFrom:
        configMapKeyRef:
          name: mysql-credentials
          key: rootpw
    - name: MYSQL_USER
      valueFrom:
        configMapKeyRef:
          name: mysql-credentials
          key: user
    - name: MYSQL_PASSWORD
      valueFrom:
        configMapKeyRef:
          name: mysql-credentials
          key: password

• 通过在Pod的命令行下运行命令方式

[k8s001 ~]# cat busybox.yaml
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: wf-mysql
spec:
  containers:
  - image: busybox
    imagePullPolicy: IfNotPresent
    command: ["/bin/sh", "-c", "echo ${test_env}"]
    name: busybox
    envFrom:
      - configMapRef:
          name: configmap-test
    restartPolicy: Always

• 作为volume的方式挂载到Pod内

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: wf-mysql
spec:
  containers:
  - image: mysql:5.7
    imagePullPolicy: IfNotPresent
    name: mysql
    env:
    - name: MYSQL_ROOT_PASSWORD
      valueFrom:
        secretKeyRef:
          name: mysql-credentials
          key: rootpw
    - name: MYSQL_USER
      valueFrom:
        secretKeyRef:
          name: mysql-credentials
          key: user
    - name: MYSQL_PASSWORD
      valueFrom:
        secretKeyRef:
          name: mysql-credentials
          key: password

    ports:
    - containerPort: 3306
      name: mysql
    volumeMounts:
    - name: config-volume
      mountPath: /etc/mysql/mysql.conf.d
  volumes:
  - name: config-volume
    configMap:
      name: mysql-config