Kubernetes部署MySQL主從服務(wù)
Kubernetes Master Kubernetes Node （測試演示，所有的副本都會在其上運行） Kubernetes DNS服務(wù)已開啟
搭建一個主從復(fù)制（Master-Slave）的MySQL集群 從節(jié)點可以水平擴展 所有的寫操作只能在主節(jié)點上執(zhí)行 讀操作可以在主從節(jié)點上執(zhí)行 從節(jié)點能同步主節(jié)點的數(shù)據(jù)
本地存儲原理
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: local-storage
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
實驗步驟
apiVersion: v1
kind: PersistentVolume
metadata:
name: example-mysql-pv
spec:
capacity:
storage: 15Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Delete
storageClassName: local-storage
local:
path: /data/svr/projects/mysql
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- 172.31.170.51
apiVersion: v1
kind: PersistentVolume
metadata:
name: example-mysql-pv-2
spec:
capacity:
storage: 15Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Delete
storageClassName: local-storage
local:
path: /data/svr/projects/mysql2
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- 172.31.170.51
apiVersion: v1
kind: PersistentVolume
metadata:
name: example-mysql-pv-3
spec:
capacity:
storage: 15Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Delete
storageClassName: local-storage
local:
path: /data/svr/projects/mysql3
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- 172.31.170.51
kubectl apply -f 01-persistentVolume-{1..3}.yaml
persistentvolume/example-mysql-pv1 created
persistentvolume/example-mysql-pv2 created
persistentvolume/example-mysql-pv3 created
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: local-storage
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
kubectl apply -f 02-storageclass.yaml
storageclass.storage.k8s.io/local-storage created
apiVersion: v1
kind: Namespace
metadata:
name: mysql
labels:
app: mysql
kubectl apply -f 03-mysql-namespace.yaml
namespace/mysql created
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
namespace: mysql
labels:
app: mysql
data:
master.cnf: |
# Master配置
[mysqld]
log-bin=mysqllog
skip-name-resolve
slave.cnf: |
# Slave配置
[mysqld]
super-read-only
skip-name-resolve
log-bin=mysql-bin
replicate-ignore-db=mysql
kubectl apply -f 04-mysql-configmap.yaml
configmap/mysql created
apiVersion: v1
kind: Secret
metadata:
name: mysql-secret
namespace: mysql
labels:
app: mysql
type: Opaque
data:
password: MTIzNDU2 # echo -n "123456" | base64
kubectl apply -f 05-mysql-secret.yaml
secret/mysql-secret created
apiVersion: v1
kind: Service
metadata:
name: mysql
namespace: mysql
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
clusterIP: None
selector:
app: mysql
---
apiVersion: v1
kind: Service
metadata:
name: mysql-read
namespace: mysql
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql
kubectl apply -f 06-mysql-services.yaml
$ kubectl get svc -n mysql
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
mysql ClusterIP None 3306/TCP 20s
mysql-read ClusterIP 10.0.0.63 3306/TCP 20s
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
namespace: mysql
labels:
app: mysql
spec:
selector:
matchLabels:
app: mysql
serviceName: mysql
replicas: 2
template:
metadata:
labels:
app: mysql
spec:
initContainers:
- name: init-mysql
image: mysql:5.7
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
command:
- bash
- "-c"
- |
set -ex
# 從Pod的序號，生成server-id
[[ $(hostname) =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
# 由于server-id不能為0，因此給ID加100來避開它
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
# 如果Pod的序號為0，說明它是Master節(jié)點，從ConfigMap里把Master的配置文件拷貝到/mnt/conf.d目錄下
# 否則，拷貝ConfigMap里的Slave的配置文件
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
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
command:
- bash
- "-c"
- |
set -ex
# 拷貝操作只需要在第一次啟動時進(jìn)行，所以數(shù)據(jù)已經(jīng)存在則跳過
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Master 節(jié)點（序號為 0）不需要這個操作
[[ $(hostname) =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal == 0 ]] && exit 0
# 使用ncat指令，遠(yuǎn)程地從前一個節(jié)點拷貝數(shù)據(jù)到本地
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# 執(zhí)行 --prepare，這樣拷貝來的數(shù)據(jù)就可以用作恢復(fù)了
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
env:
# - name: MYSQL_ALLOW_EMPTY_PASSWORD
# value: "1"
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping", "-uroot", "-p${MYSQL_ROOT_PASSWORD}"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
command: ["mysqladmin", "ping", "-uroot", "-p${MYSQL_ROOT_PASSWORD}"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: gcr.io/google-samples/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# 從備份信息文件里讀取MASTER_LOG_FILE和MASTER_LOG_POS這2個字段的值，用來拼裝集群初始化SQL
if [[ -f xtrabackup_slave_info ]]; then
# 如果xtrabackup_slave_info文件存在，說明這個備份數(shù)據(jù)來自于另一個Slave節(jié)點
# 這種情況下，XtraBackup工具在備份的時候，就已經(jīng)在這個文件里自動生成了“CHANGE MASTER TO”SQL語句
# 所以，只需要把這個文件重命名為change_master_to.sql.in，后面直接使用即可
mv xtrabackup_slave_info change_master_to.sql.in
# 所以，也就用不著xtrabackup_binlog_info了
rm -f xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# 如果只是存在xtrabackup_binlog_info文件，說明備份來自于Master節(jié)點，就需要解析這個備份信息文件，讀取所需的兩個字段的值
[[ $(cat xtrabackup_binlog_info) =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
rm xtrabackup_binlog_info
# 把兩個字段的值拼裝成SQL，寫入change_master_to.sql.in文件
echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
fi
# 如果存在change_master_to.sql.in，就意味著需要做集群初始化工作
if [[ -f change_master_to.sql.in ]]; then
# 但一定要先等MySQL容器啟動之后才能進(jìn)行下一步連接MySQL的操作
echo "Waiting for mysqld to be ready（accepting connections）"
until mysql -h 127.0.0.1 -uroot -p${MYSQL_ROOT_PASSWORD} -e "SELECT 1"; do sleep 1; done
echo "Initializing replication from clone position"
# 將文件change_master_to.sql.in改個名字
# 防止這個Container重啟的時候，因為又找到了change_master_to.sql.in，從而重復(fù)執(zhí)行一遍初始化流程
mv change_master_to.sql.in change_master_to.sql.orig
# 使用change_master_to.sql.orig的內(nèi)容，也就是前面拼裝的SQL，組成一個完整的初始化和啟動Slave的SQL語句
mysql -h 127.0.0.1 -uroot -p${MYSQL_ROOT_PASSWORD} << EOF
$(< change_master_to.sql.orig),
MASTER_HOST='mysql-0.mysql.mysql',
MASTER_USER='root',
MASTER_PASSWORD='${MYSQL_ROOT_PASSWORD}',
MASTER_CONNECT_RETRY=10;
START SLAVE;
EOF
fi
# 使用ncat監(jiān)聽3307端口。
# 它的作用是，在收到傳輸請求的時候，直接執(zhí)行xtrabackup --backup命令，備份MySQL的數(shù)據(jù)并發(fā)送給請求者
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 --password=${MYSQL_ROOT_PASSWORD}"
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
volumes:
- name: conf
emptyDir: {}
- name: config-map
configMap:
name: mysql
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes:
- "ReadWriteOnce"
storageClassName: local-storage
resources:
requests:
storage: 3Gi
整體的StatefulSet有兩個Replicas，一個Master，一個Slave，然后使用init-mysql這個initContainers進(jìn)行配置文件的初始化。接著使用clone-mysql這個initContainers進(jìn)行數(shù)據(jù)的傳輸；同時使用xtrabackup這個sidecar容器進(jìn)行SQL初始化和數(shù)據(jù)傳輸功能。
kubectl apply -f 07-mysql-statefulset.yaml
$ kubectl get po -n mysql
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 70s
mysql-1 0/2 Pending 0 5s
服務(wù)驗證
kubectl -n mysql exec mysql-1 -c mysql -- bash -c "mysql -uroot -p123456 -e 'show slave status \G'"
mysql: [Warning] Using a password on the command line interface can be insecure.
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: mysql-0.mysql.mysql
Master_User: root
Master_Port: 3306
Connect_Retry: 10
Master_Log_File: mysqllog.000003
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-1-relay-bin.000002
Relay_Log_Pos: 319
Relay_Master_Log_File: mysqllog.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 154
Relay_Log_Space: 528
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 100
Master_UUID: 1bad4d64-6290-11ea-8376-0242ac113802
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
kubectl -n mysql exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'create database test’"
kubectl -n mysql exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;create table counter(c int);’"
kubectl -n mysql exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;insert into counter values(123)’"
kubectl -n mysql exec mysql-1 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;select * from counter’"
c
123
擴展從節(jié)點
kubectl -n mysql scale statefulset mysql -—replicas=3
$ kubectl get po -n mysql
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 22m
mysql-1 2/2 Running 0 22m
mysql-2 2/2 Running 0 20s
kubectl -n mysql exec mysql-2 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;select * from counter’"
c
123
