前提假设：
1.已安装k8s环境；
2.因为我使用nfs作为pv存储介质，所以需要预先配置好nfs服务
nfs安装可参考：https://blog.csdn.net/wudinaniya/article/details/81068518
步骤：
1.规划mysql持久化文件在nfs中的存储路径；
2.创建mysql pv；
3.创建mysql configmap；
4.创建mysql service；
5.创建mysql statefulset；
6.验证mysql是否安装成功。
步骤1：
在nfs路径下（我是192.168.152.12的/home/nfs/volumes），创建mysql-datadir-1 mysql-datadir-2 mysql-datadir-3三个文件夹
mkdir mysql-datadir-1 mysql-datadir-2 mysql-datadir-3
步骤2：创建pv
pv.yaml:
指向步骤1中的3个mysql-datadir文件夹。 文件中的server填入nfs-server服务所在ip
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-datadir-1
spec:
capacity:
storage: 2Gi
accessModes: ["ReadWriteMany","ReadWriteOnce"]
nfs:
path: /home/nfs/volumes/mysql-datadir-1
server: 192.168.152.12
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-datadir-2
spec:
capacity:
storage: 2Gi
accessModes: ["ReadWriteMany","ReadWriteOnce"]
nfs:
path: /home/nfs/volumes/mysql-datadir-2
server: 192.168.152.12
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-datadir-3
spec:
capacity:
storage: 2Gi
accessModes: ["ReadWriteMany","ReadWriteOnce"]
nfs:
path: /home/nfs/volumes/mysql-datadir-3
server: 192.168.152.12
创建pv
kubectl apply -f pv.yaml
步骤3：创建mysql configmap
configmap.yaml:
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
labels:
app: mysql
data:
master.cnf: |
[mysqld]
log-bin
default-time-zone='+8:00'
log_bin_trust_function_creators=1
lower_case_table_names=1
slave.cnf: |
[mysqld]
super-read-only
default-time-zone='+8:00'
log_bin_trust_function_creators=1
创建configmap
kubectl apply -f configmap.yaml
步骤4：创建mysql service
service.yaml: 其中服务mysql用于读写；服务mysql-read用于只读。
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
创建service：
kubectl apply -f service.yaml
步骤5：创建statefulset
statefulset.yaml:
注意事项：官网或其他博客用的xtrabackup镜像无法拉取，所以使用国内阿里云的镜像替代：registry.cn-hangzhou.aliyuncs.com/hxpdocker/xtrabackup:1.0
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: 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]}
[[ $ordinal -eq 0 ]] && exit 0
# Clone data from previous peer.
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# Prepare the backup.
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
# Check we can execute queries over TCP (skip-networking is off).
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: registry.cn-hangzhou.aliyuncs.com/hxpdocker/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# Determine binlog position of cloned data, if any.
if [[ -f xtrabackup_slave_info && "x$(<xtrabackup_slave_info)" != "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 "$(<change_master_to.sql.in), \
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"]
resources:
requests:
storage: 2Gi
创建statefulset：
kubectl apply -f statefulset.yaml
可以看到，mysql pod正在初始化。因为需要拉取mysql镜像和xtrabackup镜像，所以需要等待
步骤6：验证是否安装成功
6.1查看mysql master状态并创建数据库testdb：
[root@k8s-master mysql]# kubectl exec -it mysql-0 sh # mysql mysql> show databases; mysql> show master status; mysql> create database testdb; mysql> show databases;
6.2 查看其中一个mysql slave的状态，并验证新创建的数据库testdb是否成功同步：
[root@k8s-master mysql-datadir-3]# kubectl exec -it mysql-1 sh # mysql mysql> show databases;
查看slave状态：
mysql> show slave status \G;
说明：Slave_IO_State: Waiting for master to send event 证明slave正在监听master
备注：
按照以上步骤，成功完成了基于k8s的mysql5.7主从集群安装。
过程并非顺利，可能会出现slave无法同步数据的问题。但重复安装2次后，问题消失。根因有待继续跟踪
参考链接：
https://blog.51cto.com/u_15127511/2657609
https://blog.csdn.net/weixin_43936969/article/details/106289127
https://www.cnblogs.com/cooper-73/p/12988614.html