kubernetes之配置mysql的configmap

一.簡單說明

我們在運行一個mysql服務時，mysql服務有兩類重要的數據，一個是存儲的數據、另一個是存儲的配置文件。存儲數據這里我們可以使用掛載PVC來實現持久化存儲，配置文件這里我們如果實現和容器的解耦，可以采用configmap來實現。

二.ConfigMap介紹

2.1 ConfigMap作用和使用場景

• ConfigMap用於保存配置數據，以鍵值對的形式存儲
• ConfigMap資源提供了向Pod注入配置數據的方法
• ConfigMap旨在讓鏡像與配置文件解耦，以實現鏡像的可移植性和可復用性。
• 填充環境變量的值
• 填充卷的配置文件

2.2 ConfigMap的創建

這里有以下幾種創建方式：

• 使用字面值創建

  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
  

• 使用文件創建

  [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
  

• 使用目錄創建

  [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
  

• 編寫ConfigMap的yaml文件來創建

  [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

• 可以通過環境變量的形式直接傳遞給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

• 通過在Pod的命令行下運行命令方式

[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

• 作為volume的方式掛載到Pod內

---
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