21、Kubernetes 实战 - k8s 部署 MySQL 服务（secret、deployment、service）
一，前言
上一篇，介绍基于 k8s 项目部署流程设计；
本篇，介绍 MySQL 服务的部署；
二，部署 MySQL 服务
部署MySQL
- 可以为指定 node 添加污点，专门用于 mysql 部署（当前只有一个节点，不考虑）；
- 为了保证mysql容器重启时数据不会丢失：创建 mysql 数据目录，用于存储 mysql 数据，实现 MySQL 数据的持久化；
- 创建 Secret 对象，向为 mysql 容器提供用户名、密码信息；
- 创建 mysql Deployment 配置文件，并创建 deploy 完成 pod 部署；
- 创建 mysql Service 配置文件，并创建 service 解决 ip 漂移问题，对外提供 pod 访问；
- 为 k8s-master 安装 mysql，使 k8s-master 能够使用 mysql 命令，测试数据库使用；
三，MySQL 数据的持久化
容器中的数据是需要保留的，否则容器重启就没了，需要创建数据目录，存储 MySQL 数据；
在本地创建 MySQL 数据文件夹，然后挂载到 MySQL 容器，实现 MySQL 数据的可以持久化
在k8s-node 节点创建 MySQL 数据文件夹（此文件夹必须为空，否则导致 MySQL 启动失败；
// 创建数据目录文件夹（mysql 运行时的数据目录，约定好的）
[root@k8s-master ~]# mkdir /var/lib/mysql
[root@k8s-master ~]# ll /var/lib/mysql
总用量 0
创建一个新的文件夹：cicd
将所有的配置文件都放在这个cicd目录下
[root@k8s-master ~]# mkdir cicd
[root@k8s-master ~]# cd cicd/
[root@k8s-master cicd]#
四，创建 Secret 对象
通过Secret 对象，将 MySQL 的用户名、密码传递到镜像中使用；
创建Secret 对象：mysql-auth
// 创建 secret，generic：基于普通文本格式，--from-literal：从字面量创建
[root@k8s-master cicd]# kubectl create secret generic mysql-auth --from-literal=username=root --from-literal=password=123456
secret/mysql-auth created
[root@k8s-master cicd]# kubectl get secret mysql-auth
NAME TYPE DATA AGE
mysql-auth Opaque 2 17s
[root@k8s-master cicd]# kubectl get secret mysql-auth -o yaml
apiVersion: v1
data:
password: MTIzNDU2
username: cm9vdA==
kind: Secret
metadata:
creationTimestamp: "2022-01-06T07:14:25Z"
managedFields:
- apiVersion: v1
fieldsType: FieldsV1
fieldsV1:
f:data:
.: {}
f:password: {}
f:username: {}
f:type: {}
manager: kubectl-create
operation: Update
time: "2022-01-06T07:14:25Z"
name: mysql-auth
namespace: default
resourceVersion: "1934676"
uid: c4a219d2-3754-4133-8484-9b4caa5a54cd
type: Opaque
[root@k8s-master cicd]# echo MTIzNDU2 | base64 -d
123456
[root@k8s-master cicd]# echo cm9vdA== | base64 -d
root
五，创建 Deployment
创建mysql Deployment 配置文件，并创建 deploy 完成 pod 部署；
创建deploy：deployment-cicd-mysql.yaml
[root@k8s-master cicd]# vi deployment-cicd-mysql.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: cicd-mysql
spec:
replicas: 1
selector:
matchLabels:
app: cicd-mysql
template:
metadata:
labels:
app: cicd-mysql
spec:
containers:
- name: cicd-mysql
image: mysql:5.7
imagePullPolicy: IfNotPresent镜像拉取策略:如果不存在就拉取镜像
args:
- "--ignore-db-dir=lost+found"
ports:
- containerPort: 3306
volumeMounts:挂载数据卷
- name: mysql-data
mountPath: "/var/lib/mysql"挂载到容器内的目录
env:环境变量
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-auth
key: password引用mysql-auth中的password值
volumes:数据卷
- name: mysql-data
hostPath:宿主机路径
path: /var/lib/mysql宿主机的目录
type: Directory
备注：以下配置文档中有，但视频没用
tolerations:
- key: "mysql"
operator: "Equal"
value: "true"
effect: "NoSchedule"
备注：
mysql 自带 root 用户，只设置 root 用户密码即可使用；
环境变量 env MYSQL_ROOT_PASSWORD 是在 mysql:5.7 的镜像中约定的；
mysql容器启动成功后，会读取到 MYSQL_ROOT_PASSWORD 并设置为密码；
如：docker run mysql:5.7 --env PASSWORD=123
生效配置
[root@k8s-master cicd]# kubectl apply -f deployment-cicd-mysql.yaml
deployment.apps/cicd-mysql created
[root@k8s-master cicd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
cicd-mysql-745975859b-kstnh 0/1 Pending 0 65s
pay-v1-6db6455b8-np2hw 1/1 Running 0 6h38m
user-v1-9f4d589cc-rdmnz 1/1 Running 0 24h
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 7d
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 2d17h
清理一下资源，删除 pay-v1、user-v1、v4 的 deploy
[root@k8s-master cicd]# kubectl delete deploy pay-v1 user-v1 v4
deployment.apps "pay-v1" deleted
deployment.apps "user-v1" deleted
deployment.apps "v4" deleted
[root@k8s-master cicd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
cicd-mysql-745975859b-kstnh 0/1 Pending 0 4m8s
cicd-mysql-745975859b-kstnh 这个 pod 是 pending 状态
[root@k8s-master cicd]# kubectl describe pods cicd-mysql-745975859b-kstnh
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 49s (x7 over 4m51s) default-scheduler 0/2 nodes are available: 1 node(s) had taint {node-role.kubernetes.io/master: }, that the pod didn't tolerate, 1 node(s) had taint {pay-v1: true}, that the pod didn't tolerate.
kubectl logs cicd-mysql-6cbd4f95-g64hh
这是因为，k8s-node 服务器之前配置了 pay-v1: true，需要删除掉污点
// 查看污点
[root@k8s-master cicd]# kubectl describe node k8s-node
Taints: pay-v1=true:NoSchedule
// 删除污点
[root@k8s-master cicd]# kubectl taint nodes k8s-node pay-v1-
node/k8s-node untainted
// 再次查看，没有污点了
[root@k8s-master cicd]# kubectl describe node k8s-node
Taints: <none>
再看pod 信息，已经在创建中了
[root@k8s-master cicd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
cicd-mysql-745975859b-kstnh 0/1 ContainerCreating 0 20m
但是有些问题，再看一下容器描述
[root@k8s-master cicd]# kubectl describe pods cicd-mysql-745975859b-kstnh
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 6m58s (x20 over 24m) default-scheduler 0/2 nodes are available: 1 node(s) had taint {node-role.kubernetes.io/master: }, that the pod didn't tolerate, 1 node(s) had taint {pay-v1: true}, that the pod didn't tolerate.
Normal Scheduled 6m36s default-scheduler Successfully assigned default/cicd-mysql-745975859b-kstnh to k8s-node
Warning FailedMount 2m15s (x2 over 4m33s) kubelet Unable to attach or mount volumes: unmounted volumes=[mysql-data], unattached volumes=[mysql-data default-token-q4qxd]: timed out waiting for the condition
Warning FailedMount 24s (x11 over 6m35s) kubelet MountVolume.SetUp failed for volume "mysql-data" : hostPath type check failed: /var/lib/mysql is not a directory
原因是，pod 在 k8s-node 服务器上部署，但 k8s-node 服务器上并没有/var/lib/mysql目录
所以，需要在 k8s-node 服务器上创建/var/lib/mysql目录
[root@k8s-node ~]# mkdir /var/lib/mysql
删除pod，再看新启动的 pod，已经正常 Running
（注意：1，不删除 pod 过一会儿也会正常 Running；2，删除 pod后，副本会重新创建）
[root@k8s-master deployment]# kubectl delete pod cicd-mysql-745975859b-kstnh
pod "cicd-mysql-745975859b-kstnh" deleted
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
cicd-mysql-745975859b-gpwzh 1/1 Running 0 10s
[root@k8s-master deployment]# kubectl describe pods cicd-mysql-745975859b-gpwzh
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 29s default-scheduler Successfully assigned default/cicd-mysql-745975859b-gpwzh to k8s-node
Normal Pulled 25s kubelet Container image "mysql:5.7" already present on machine
Normal Created 25s kubelet Created container cicd-mysql
Normal Started 25s kubelet Started container cicd-mysql
查看日志：
[root@k8s-master deployment]# kubectl logs cicd-mysql-745975859b-gpwzh
2022-01-07T01:39:13.425378Z 0 [Note] mysqld: ready for connections.
Version: '5.7.36' socket: '/var/run/mysqld/mysqld.sock' port: 3306 MySQL Community Server (GPL)
mysql 已经启动成功，等待连接
六，k8s-master 安装 mysql 命令
为k8s-master 安装 mysql，使 k8s-master 能够使用 mysql 命令，测试数据库使用；
由于k8s-maste 没有安装 mysql 所以不能使用 mysql 命令
1，k8s-maste 安装 mysql
2，可以进入容器中操作
[root@k8s-master deployment]# kubectl exec -it cicd-mysql-745975859b-gpwzh -- bash
root@cicd-mysql-745975859b-gpwzh:/# mysql -uroot -p123456
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 4
Server version: 5.7.36 MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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> show databases;
++
| Database |
++
| information_schema |
| mysql |
| performance_schema |
| sys |
++
4 rows in set (0.01 sec)
mysql> show tables;
+----------------+
| Tables_in_cicd |
+----------------+
| users |
+----------------+
1 row in set (0.00 sec)
mysql> select * from users;
Empty set (0.00 sec)
\
创建cicd 数据库，创建表
mysql> create database cicd;
Query OK, 1 row affected (0.04 sec)
mysql> use cicd;
Database changed
mysql>` CREATE TABLE users (
->` id int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
->` name varchar(255) NOT NULL COMMENT '',
->` age int(11) NOT NULL COMMENT '',
->` sex varchar(255) NOT NULL COMMENT '1 2',
->` PRIMARY KEY (id)
-> ) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.03 sec)
退出mysql，退出pod，回到 k8s-master
mysql> exit;
Bye
root@cicd-mysql-745975859b-gpwzh:/# exit
exit
给k8s-master 安装 mysql：
// 下载MySQL源安装包
wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm
// 安装MySQL源
yum -y install mysql57-community-release-el7-11.noarch.rpm
// 安装 mysql
yum install mysql-community-server -y
k8s-master 访问 MySQL
[root@k8s-master ~]# cat /etc/hosts
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
172.17.178.106 k8s-node
172.17.178.105 k8s-master
[root@k8s-master cicd]# mysql -h172.17.178.105 -P3306 -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 2003 (HY000): Can't connect to MySQL server on '172.17.178.105' (111)
还不能访问，因为没有服务
七，创建 Service
由于pod 的 ip 是会漂移的， 需要通过 Service 访问 pod，需要创建服务
创建service：service-cicd-mysql.yaml
[root@k8s-master cicd]# vi service-cicd-mysql.yaml
apiVersion: v1
kind: Service
metadata:源数据
name: service-cicd-mysql
spec:规格
selector:选择器
app: cicd-mysql与deployment配置中的container-name相对应
ports:将pod的 3306端口代理到宿主机的3306端口
- protocol: TCP
port: 3306
targetPort: 3306虚拟端口->真正的端口要看Service启动后实际分配的
type: NodePort不写就不能访问到pod
生效配置，服务启动
[root@k8s-master cicd]# kubectl apply -f service-cicd-mysql.yaml
service/service-cicd-mysql created
[root@k8s-master cicd]# kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 16d
service-cicd-mysql NodePort 10.108.224.96 <none> 3306:30509/TCP 11s
service-pay-v1 NodePort 10.97.250.199 <none> 80:30114/TCP 2d19h
service-user-v1 NodePort 10.104.13.40 <none> 80:31071/TCP 14d
3306:30509 服务的内部端口/外部端口（外部访问 Service 中的 mysql 服务使用的端口号）
数据库端口：访问 Service 的 30509 端口
[root@k8s-master cicd]# mysql -h172.17.178.105 -P30509 -uroot -p123456
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 7
Server version: 5.7.36 MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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> use cicd;
Database changed
mysql> show tables;
+----------------+
| Tables_in_cicd |
+----------------+
| users |
+----------------+
1 row in set (0.00 sec)
mysql> exit;
Bye
数据库配置完成；
八，结尾
本篇，完成了 mysql 服务的创建和测试；
下一篇，介绍后端服务的部署；