Introduction to MySql
MySQL is a relational database management system developed by the Swedish company MySQL AB and is a product of Oracle. MySQL is one of the most popular relational database management systems. In terms of web applications, MySQL is one of the best RDBMS (Relational Database Management System) application software. MySQL is a relational database management system. Relational databases store data in different tables instead of putting all data in a large warehouse, which increases speed and flexibility. The SQL language used by MySQL is the most commonly used standardized language for accessing databases. MySQL software adopts a dual authorization policy, divided into community version and commercial version. Due to its small size, fast speed, low total cost of ownership, especially the characteristics of open source, the development of small and medium-sized websites generally chooses MySQL as the website database.
MySQL's high-availability solution
The MySQL high-availability solution introduced below uses master-slave replication + read-write separation, which is composed of a single master and multiple slaves. Among them, the client writes to the database through the master, and reads through the slave. After the master has a problem, you can switch the application to the slave side. This solution is a highly available solution officially provided by MySQL. Data synchronization between nodes uses MySQL Replication technology. MySQL Replication replicates data from one MySQL database server (master) to one or more MySQL database servers (slave). By default, replication is asynchronous; the slave does not need to always receive updates from the host. Depending on the configuration, all databases in the database, selected databases, or specific tables can be copied.
Installation and deployment
1. Create a ConfigMap
Create a ConfigMap named mysql through the YAML file
cat mysql-configmap.yaml
apiVersion:v1
kind:ConfigMap
metadata:
name:mysql
labels:
app:mysql
data:
master.cnf:|
# Apply this config only on the master.
[mysqld]
log-bin
log_bin_trust_function_creators=1
lower_case_table_names=1
slave.cnf:|
# Apply this config only on slaves.
[mysqld]
super-read-only
log_bin_trust_function_creators=1
kubectl apply -f mysql-configmap.yaml -n kube-public
2. 创建Services
通过yaml文件创建两个service，分别是mysql和mysql-read：
cat mysql-service.yaml
apiVersion: v1 kind: Service metadata: name: mysql labels: app: mysql spec: ports: - name: mysql port: 3306 clusterIP: None selector: app: mysql --- apiVersion: v1 kind: Service metadata: name: mysql-read labels: app: mysql spec: ports: - name: mysql port: 3306 selector: app: mysql
kubectl apply -f mysql-service.yaml -n kube-public
3.创建StatefulSet
通过yaml文件创建名为mysql的StatefulSet：
cat mysql-statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
serviceName: mysql
replicas: 3
volumeClaimTemplates:
- metadata:
name: data
annotations:
volume.beta.kubernetes.io/storage-class: "nfs"
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 10Gi
template:
metadata:
labels:
app: mysql
spec:
initContainers:
- name: init-mysql
image: mysql:5.7
command:
- bash
- "-c"
- |
set -ex
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
if [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/master.cnf /mnt/conf.d/
else
cp /mnt/config-map/slave.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: gcr.io/google-samples/xtrabackup:1.0
command:
- bash
- "-c"
- |
set -ex
[[ -d /var/lib/mysql/mysql ]] && exit 0
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: gcr.io/google-samples/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
if [[ -f xtrabackup_slave_info ]]; then
mv xtrabackup_slave_info change_master_to.sql.in
rm -f xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
rm xtrabackup_binlog_info
echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
fi
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"
mv change_master_to.sql.in change_master_to.sql.orig
mysql -h 127.0.0.1 <<EOF
$(<change_master_to.sql.orig),
MASTER_HOST='mysql-0.mysql',
MASTER_USER='root',
MASTER_PASSWORD='',
MASTER_CONNECT_RETRY=10;
START SLAVE;
EOF
fi
exec ncat --listen --keep-open --send-only --max-conns=1 3307 -c \
"xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root"
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 100m
memory: 100Mi
volumes:
- name: conf
emptyDir: {}
- name: config-map
configMap:
name: mysql
kubectl apply -f mysql-statefulset.yaml -n kube-public
通过执行如下的命令可以查看启动过程：
$ kubectl get pods -lapp=mysql --watch --namespace=kube-public
在启动后，应该能够看到如下的信息：
注：上面配置说明
volumeClaimTemplates:
- metadata:
name: data
annotations:
volume.beta.kubernetes.io/storage-class: "nfs"
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 10Gi
上面这段表示动态申请pvc，存储类是由nfs创建的，前提是创建nfs的存储类，创建方法如下：
cat class.yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: nfs
provisioner: example.com/nfs
kubectl apply -f class.yaml
动态pvc创建可参考：
MySQL部署环境验证
1）通过运行一个临时的容器(使用mysql:5.7镜像)，使用MySQL 客户端发送测试请求给MySQL master节点（主机名为mysql-0.mysql；跨命名空间的话，主机名请使用mysql-0.mysql.kube-public）
kubectl run mysql-client --image=mysql:5.7 -it --rm --restart=Never -- mysql -h mysql-0.mysql.kube-public
CREATE DATABASE demo;
CREATE TABLE demo.messages (message VARCHAR(250));
INSERT INTO demo.messages VALUES ('hello');
在master节点上创建demo数据库，并创建一个只有message字段的demo.messages的表，并为message字段插入hello值。
2）使用主机名为mysql-read来发送测试请求给服务器：
kubectl run mysql-client --image=mysql:5.7 -i -t --rm --restart=Never -- mysql -h mysql-read.kube-public
