kubernetes安装MySql 5.7主从复制集群
一、部署原理
使用 statefulset控制器部署mysql主从集群的原理如下图所示：
官方地址： Run a Replicated Stateful
参考博客：CSDN博客 阿里云博客
二、使用 statefulset控制器部署mysql主从集群
2.1、首先从资源清单创建ConfigMap
[root@master-dev mysql_cluster]# 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
slave.cnf: |
# Apply this config only on slaves.
[mysqld]
super-read-only
2.2、创建Service，提供服务的访问和负载均衡
# Headless service for stable DNS entries of StatefulSet members.
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
[root@master-dev mysql_cluster]# kubectl apply -f mysql-services.yaml
service/mysql created
service/mysql-read created
[root@master-dev mysql_cluster]# kubectl get svc | grep mysql
mysql ClusterIP None <none> 3306/TCP 1s
mysql-read ClusterIP 10.111.232.160 <none> 3306/TCP 1s
2.3、部署statefulset控制器创建Pod
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
serviceName: mysql
replicas: 3
template:
metadata:
labels:
app: mysql
spec:
initContainers:
- name: init-mysql
image: registry.cn-hangzhou.aliyuncs.com/public_ns/mysql:5.7
command:
- bash
- "-c"
- |
set -ex
# Generate mysql server-id from pod ordinal index.
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
# Add an offset to avoid reserved server-id=0 value.
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
# Copy appropriate conf.d files from config-map to emptyDir.
if [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/master.cnf /mnt/conf.d/
else
cp /mnt/config-map/slave.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: registry.cn-hangzhou.aliyuncs.com/hxpdocker/xtrabackup:1.0
command:
- bash
- "-c"
- |
set -ex
# Skip the clone if data already exists.
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Skip the clone on master (ordinal index 0).
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
# Clone data from previous peer.
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# Prepare the backup.
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: registry.cn-hangzhou.aliyuncs.com/public_ns/mysql:5.7
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
# Check we can execute queries over TCP (skip-networking is off).
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: registry.cn-hangzhou.aliyuncs.com/hxpdocker/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# Determine binlog position of cloned data, if any.
if [[ -f xtrabackup_slave_info && "x$(!= "x" ]]; then
# XtraBackup already generated a partial "CHANGE MASTER TO" query
# because we're cloning from an existing slave. (Need to remove the tailing semicolon!)
cat xtrabackup_slave_info | sed -E 's/;$//g' > change_master_to.sql.in
# Ignore xtrabackup_binlog_info in this case (it's useless).
rm -f xtrabackup_slave_info xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# We're cloning directly from master. Parse binlog position.
[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || 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
# Check if we need to complete a clone by starting replication.
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 "$(, \
MASTER_HOST='mysql-0.mysql', \
MASTER_USER='root', \
MASTER_PASSWORD='', \
MASTER_CONNECT_RETRY=10; \
START SLAVE;" || exit 1
# In case of container restart, attempt this at-most-once.
mv change_master_to.sql.in change_master_to.sql.orig
fi
# Start a server to send backups when requested by peers.
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
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes: ["ReadWriteOnce"]
storageClassName: "nfs-client" #!!!这里需要提前创建好storageClass，或者对应的PVC
resources:
requests:
storage: 10Gi
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-statefulset.yaml
kubectl get pods -l app=mysql --watch
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 2m
mysql-1 2/2 Running 0 1m
mysql-2 2/2 Running 0 1m
如若没有storageClass，需要创建一下pv和pvc
kubectl apply -f cat data_pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: data
labels:
release: "stable"
spec:
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
storageClassName: mynfs
persistentVolumeReclaimPolicy: Recycle
nfs:
path: "/eastorage"
server: 10.19.86.144
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: data1
labels:
release: "stable"
spec:
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
storageClassName: mynfs1
persistentVolumeReclaimPolicy: Recycle
nfs:
path: "/emptydir"
server: 10.19.86.144
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: data2
labels:
release: "stable"
spec:
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
storageClassName: mynfs2
persistentVolumeReclaimPolicy: Recycle
nfs:
path: "/docker"
server: 10.19.86.144
kubectl apply -f cat data_pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: data-mysql-0
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: mynfs
selector:
matchLabels:
release: "stable"
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: data-mysql-1
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: mynfs1
selector:
matchLabels:
release: "stable"
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: data-mysql-2
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: mynfs2
selector:
matchLabels:
release: "stable"
三、主从测试
可以通过运行带有 mysql:5.7 镜像的临时容器并运行 mysql 客户端二进制文件，将测试查询发送到 MySQL 主服务器(主机名 mysql-0.mysql )
[root@master-dev mysql]# kubectl run test --image=registry.cn-hangzhou.aliyuncs.com/public_ns/mysql:5.7 -it -- bash
root@test:/# mysql -h mysql-0.mysql
mysql> create database redhat;
Query OK, 1 row affected (0.11 sec)
mysql> show databases;
+------------------------+
| Database |
+------------------------+
| information_schema |
| mysql |
| performance_schema |
| redhat |
| sys |
| xtrabackup_backupfiles |
+------------------------+
6 rows in set (0.04 sec)
通过访问mysql-read来查看创建的数据库是否在从库创建：
[root@master-dev mysql_cluster]# kubectl get svc | grep mysql
mysql ClusterIP None <none> 3306/TCP 11m
mysql-read ClusterIP 10.111.232.160 <none> 3306/TCP 11m
[root@master-dev mysql]# kubectl attach test -it
root@test:/# mysql -h 10.111.232.160
mysql> show databases;
+------------------------+
| Database |
+------------------------+
| information_schema |
| mysql |
| performance_schema |
| redhat |
| sys |
| xtrabackup_backupfiles |
+------------------------+
6 rows in set (0.05 sec)
可以看出从库复制了主库的操作,也可以直接访问从库进行验证，本文记录的重点就是在部署statefulset时处理存储问题，需要提前准备好nfs服务，或者有动态的storageClass，否则会处于pengding状态。
总结：
后面进行数据测试的时候，需要使用NaviCat去连接和导入数据测试，但是我们的服务是ClusterIP进行暴露服务，这时候我们需要修改我们的服务，但是集群只有mysql-0是主节点，可以写入数据，其他从库只提供读请求，如果只是单纯的将Service使用NodePort进行暴露，将会负载均衡到三个数据库，导致数据有可能不一致
1、先将pod打上特定标签
kubectl label pod mysql-0 role=master
2、在service里面将selector选择到这个标签，然后一直保持连接主库
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
role: master
spec:
ports:
- name: mysql
port: 3306
# clusterIP: None
selector:
role: master
type: NodePort
---
# 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