Kubernetes 部署 MySQL 集群
简介： 在有状态应用中，MySQL是我们最常见也是最常用的。本文我们将实战部署一个一组多从的MySQL集群。
一、配置准备
configMap
cat > mysql-configmap.yaml << EOF
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
labels:
app: mysql
data:
master.cnf: |
# Apply this config only on the master.
[mysqld]
log-bin
slave.cnf: |
# Apply this config only on slaves.
[mysqld]
super-read-only
EOFconfigMap可以将配置文件和镜像解耦开。
上面的配置意思是，创建一个master.cnf文件配置内容为：log-bin，即开启bin-log日志，供主节点使用。
创建一个slave.cnf文件配置内容为：super-read-only，设为该节点只读，供备用节点使用。
service
cat > mysql-services.yaml << EOF
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
clusterIP: None
selector:
app: mysql
---
# Client service for connecting to any MySQL instance for reads.
# For writes, you must instead connect to the master: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
name: mysql-read
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql
EOFStatefulSet
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
serviceName: mysql
replicas: 3
template:
metadata:
labels:
app: mysql
spec:
# 设置初始化容器，进行一些准备工作
initContainers:
- name: init-mysql
image: mysql:5.7
# 为每个MySQL节点配置service-id
# 如果节点序号是0，则使用master的配置， 其余节点使用slave的配置
command:
- bash
- "-c"
- |
set -ex
# 基于 Pod 序号生成 MySQL 服务器的 ID。
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
# 添加偏移量以避免使用 server-id=0 这一保留值。
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
# Copy appropriate conf.d files from config-map to emptyDir.
# 将合适的 conf.d 文件从 config-map 复制到 emptyDir。
if [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/master.cnf /mnt/conf.d/
else
cp /mnt/config-map/slave.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: registry.cn-hangzhou.aliyuncs.com/chenby/xtrabackup:1.0
# 为除了节点序号为0的主节点外的其它节点，备份前一个节点的数据
command:
- bash
- "-c"
- |
set -ex
# 如果已有数据，则跳过克隆。
[[ -d /var/lib/mysql/mysql ]] && exit 0
# 跳过主实例（序号索引 0）的克隆。
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
# 从原来的对等节点克隆数据。
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# 准备备份。
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
# 设置支持免密登录
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
# 设置启动pod需要的资源，官方文档上需要500m cpu，1Gi memory。
# 我本地测试的时候，会因为资源不足，报1 Insufficient cpu, 1 Insufficient memory错误，所以我改小了点
requests:
# m是千分之一的意思，100m表示需要0.1个cpu
cpu: 1024m
# Mi是兆的意思，需要100M 内存
memory: 1Gi
livenessProbe:
# 使用mysqladmin ping命令，对MySQL节点进行探活检测
# 在节点部署完30秒后开始，每10秒检测一次，超时时间为5秒
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
# 对节点服务可用性进行检测， 启动5秒后开始，每2秒检测一次，超时时间1秒
exec:
# 检查我们是否可以通过 TCP 执行查询（skip-networking 是关闭的）。
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: registry.cn-hangzhou.aliyuncs.com/chenby/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
# 开始进行备份文件校验、解析和开始同步
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# 确定克隆数据的 binlog 位置（如果有的话）。
if [[ -f xtrabackup_slave_info && "x$( change_master_to.sql.in
# 在这里要忽略 xtrabackup_binlog_info （它是没用的）。
rm -f xtrabackup_slave_info xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# 我们直接从主实例进行克隆。解析 binlog 位置。
[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
rm -f xtrabackup_binlog_info xtrabackup_slave_info
echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
fi
# 检查我们是否需要通过启动复制来完成克隆。
if [[ -f change_master_to.sql.in ]]; then
echo "Waiting for mysqld to be ready (accepting connections)"
until mysql -h 127.0.0.1 -e "SELECT 1"; do sleep 1; done
echo "Initializing replication from clone position"
mysql -h 127.0.0.1 \
-e "$( 二、创建所需资源
# 创建configMap
kubectl apply -f mysql-configmap.yaml
# 创建service
kubectl apply -f mysql-services.yaml
# 创建statefulSet
kubectl apply -f mysql-statefulset.yaml
# 查看创建过程
kubectl get pods --watch
mysql-0 0/2 Pending 0 0s
mysql-0 0/2 Pending 0 0s
mysql-0 0/2 Init:0/2 0 0s
mysql-0 0/2 Init:0/2 0 1s
mysql-0 0/2 Init:1/2 0 2s
mysql-0 0/2 PodInitializing 0 3s
mysql-0 1/2 Running 0 4s
mysql-0 2/2 Running 0 8s
mysql-1 0/2 Pending 0 0s
mysql-1 0/2 Pending 0 0s
mysql-1 0/2 Init:0/2 0 0s
mysql-1 0/2 Init:0/2 0 1s
mysql-1 0/2 Init:1/2 0 1s
mysql-1 0/2 PodInitializing 0 2s
mysql-1 1/2 Running 0 3s
mysql-1 2/2 Running 0 8s
mysql-2 0/2 Pending 0 0s
mysql-2 0/2 Pending 0 0s
mysql-2 0/2 Init:0/2 0 0s
mysql-2 0/2 Init:0/2 0 1s
mysql-2 0/2 Init:1/2 0 2s
mysql-2 0/2 PodInitializing 0 3s
mysql-2 1/2 Running 0 4s
mysql-2 2/2 Running 0 9s三、测试主库
进入pod进行操作
# 进入到pod mysql-0中，进行测试
kubectl exec -it mysql-0 bash
# 用mysql-client链接mysql-0
mysql -h mysql-0
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 276
Server version: 5.7.38-log MySQL Community Server (GPL)
Copyright (c) 2000, 2022, 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>创建库、表
# 创建数据库test
mysql> create database cby;
Query OK, 1 row affected (0.00 sec)
# 使用test库
mysql> use cby;
Database changed
# 创建message表
mysql> create table message (message varchar(50));
Query OK, 0 rows affected (0.01 sec)
# 查看message表结构
mysql> show create table message;
+---------+------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+---------+------------------------------------------------------------------------------------------------------+
| message | CREATE TABLE `message` (
`message` varchar(50) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+---------+------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
插入数据
# 插入
mysql> insert into message value("hello chenby");
Query OK, 1 row affected (0.00 sec)
# 查看
mysql> select * from message;
+---------------+
| message |
+---------------+
| hello chenby |
+---------------+
1 row in set (0.00 sec)
四、测试备库
连接mysql-1
mysql -h mysql-1.mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 362
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, 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>
mysql>
查看库、表结构
# 查看数据库列表
mysql> show databases;
+------------------------+
| Database |
+------------------------+
| information_schema |
| cby |
| mysql |
| performance_schema |
| sys |
| test |
| xtrabackup_backupfiles |
+------------------------+
7 rows in set (0.01 sec)
# 使用cby库
mysql> use cby;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql>
# 查看表列表
mysql> show tables;
+---------------+
| Tables_in_cby |
+---------------+
| message |
+---------------+
1 row in set (0.00 sec)
# 查看message表结构
mysql> show create table message;
+---------+------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+---------+------------------------------------------------------------------------------------------------------+
| message | CREATE TABLE `message` (
`message` varchar(50) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+---------+------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql>
# 查询数据
mysql> select * from message;
+---------------+
| message |
+---------------+
| hello chenby |
+---------------+
1 row in set (0.00 sec)
mysql>
# 写入数据
mysql> insert into message values("hello world");
ERROR 1290 (HY000): The MySQL server is running with the --super-read-only option so it cannot execute this statement
mysql>
# 这是因为mysql-1是一个只读备库，无法进行写操作。五、测试mysql-read服务
循环中运行 SELECT @@server_id
kubectl run mysql-client-loop --image=mysql:5.7 -i -t --rm --restart=Never --\
> bash -ic "while sleep 1; do mysql -h mysql-read -e 'SELECT @@server_id,NOW()'; done"
If you don't see a command prompt, try pressing enter.
+-------------+---------------------+
| @@server_id | NOW() |
+-------------+---------------------+
| 102 | 2022-06-07 09:52:19 |
+-------------+---------------------+
+-------------+---------------------+
| @@server_id | NOW() |
+-------------+---------------------+
| 101 | 2022-06-07 09:52:20 |
+-------------+---------------------+
+-------------+---------------------+
| @@server_id | NOW() |
+-------------+---------------------+
| 100 | 2022-06-07 09:52:21 |
+-------------+---------------------+
六、扩缩容
# 扩容至5副本
kubectl scale statefulset mysql --replicas=5
# 查看扩容过程
kubectl get pods --watch
mysql-3 0/2 Pending 0 0s
mysql-3 0/2 Pending 0 1s
mysql-3 0/2 Pending 0 2s
mysql-3 0/2 Init:0/2 0 2s
mysql-3 0/2 Init:0/2 0 2s
mysql-3 0/2 Init:0/2 0 3s
mysql-3 0/2 Init:1/2 0 4s
mysql-3 0/2 Init:1/2 0 5s
mysql-3 0/2 PodInitializing 0 12s
mysql-3 1/2 Error 0 13s
mysql-3 1/2 Running 1 (2s ago) 14s
mysql-3 2/2 Running 1 (6s ago) 18s
mysql-4 0/2 Pending 0 0s
mysql-4 0/2 Pending 0 0s
mysql-4 0/2 Pending 0 2s
mysql-4 0/2 Init:0/2 0 2s
mysql-4 0/2 Init:0/2 0 2s
mysql-4 0/2 Init:1/2 0 3s
mysql-4 0/2 Init:1/2 0 4s
mysql-4 0/2 PodInitializing 0 12s
mysql-4 1/2 Error 0 13s
mysql-4 1/2 Running 1 (1s ago) 14s
mysql-4 2/2 Running 1 (7s ago) 20s
# 缩容只2副本
kubectl scale statefulset mysql --replicas=2
# 查看缩容过程
kubectl get pods --watch
mysql-4 2/2 Terminating 1 (74s ago) 87s
mysql-4 2/2 Terminating 1 (104s ago) 117s
mysql-4 0/2 Terminating 1 118s
mysql-4 0/2 Terminating 1 118s
mysql-4 0/2 Terminating 1 118s
mysql-3 2/2 Terminating 1 (2m4s ago) 2m16s
mysql-3 2/2 Terminating 1 (2m34s ago) 2m46s
mysql-3 0/2 Terminating 1 2m47s
mysql-3 0/2 Terminating 1 2m47s
mysql-3 0/2 Terminating 1 2m47s
mysql-2 2/2 Terminating 0 16m
mysql-2 2/2 Terminating 0 16m
mysql-2 0/2 Terminating 0 16m
mysql-2 0/2 Terminating 0 16m
mysql-2 0/2 Terminating 0 16mhttps://www.oiox.cn/
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