k8s部署mysql集群master--slave

Posted 2020-12-21

一、环境信息

CentOS Linux release 7.8.2003 (Core)

4.4.240-1.el7.elrepo.x86_64

k8s 集群版本：1.15

docker 版本：Docker version 17.03.3-ce

集群信息：

NAME       STATUS   ROLES    AGE    VERSION
km-1.11    Ready    master   7d7h   v1.15.1
kn-1.11    Ready    <none>   7d7h   v1.15.1
kn1-1.11   Ready    <none>   31h    v1.15.1

二、mysql的高可用方案

MySQL高可用方案采用主从复制+读写分离，即由单一的master和多个slave所构成。其中，客户端通过master对数据库进行写操作，通过slave端进行读操作。master出现问题后，可以将应用切换到slave端。 此方案是MySQL官方提供的一种高可用解决方案，节点间的数据同步采用MySQL Replication技术。MySQL Replication从一个MySQL数据库服务器（master）的数据复制到一个或多个MySQL数据库服务器（slave）。在默认情况下，复制是异步的；slave不需要一直接收来自主机的更新。根据配置，可以复制数据库中的所有数据库、选定的数据库，或者特定的表。

三、架构说明

通过mysql+xtrabackup的模式来组成数据库master+slave的模式，具体的架构图如下所示：

四、创建StorageClass

因为需要把数据库数据持久化存储，因此需要为pod自动创建pv，pvc

参考：https://blog.51cto.com/lingxudong/2546982

[root@km-1 storageclass]# cat nfs-client.yaml
kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-client-provisioner
  namespace: blog
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-client-provisioner
  template:
    metadata:
      namespace: blog
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: quay.io/external_storage/nfs-client-provisioner:latest
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: fuseim.pri/ifs
            - name: NFS_SERVER
              value: 192.168.140.50
            - name: NFS_PATH
              value: /data/k8s
      volumes:
        - name: nfs-client-root
          nfs:
            server: 192.168.140.50
            path: /data/k8s

[root@km-1 storageclass]# cat nfs-client-sa.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  namespace: blog
  name: nfs-client-provisioner

---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: blog
  name: nfs-client-provisioner-runner
rules:
  - apiGroups: [""]
    resources: ["persistentvolumes"]
    verbs: ["get", "list", "watch", "create", "delete"]
  - apiGroups: [""]
    resources: ["persistentvolumeclaims"]
    verbs: ["get", "list", "watch", "update"]
  - apiGroups: ["storage.k8s.io"]
    resources: ["storageclasses"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["list", "watch", "create", "update", "patch"]
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["create", "delete", "get", "list", "watch", "patch", "update"]

---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: blog
  name: run-nfs-client-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    namespace: blog
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io

[root@km-1 storageclass]# cat nfs-client-class.yaml 
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  namespace: blog
  name: course-nfs-storage
provisioner: fuseim.pri/ifs 

五、staefulset搭建Mysql集群

1、创建yaml

Yaml配置如下：

[root@km-1 mysql]# cat configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  namespace: blog
  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

部署headless服务，有状态服务都需要，让服务旗下的Pod彼此发现

[root@km-1 mysql]# cat service.yaml
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
  namespace: blog
  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:
 # namespace: blog
 # name: mysql-read
#  labels:
 #   app: mysql
#spec:
 # ports:
  #- name: mysql
 #   port: 3306
  #selector:
   # app: mysql

[root@km-1 mysql]# cat statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  namespace: blog
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  serviceName: mysql
  replicas: 3
  template:
    metadata:
      namespace: blog
      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 [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: hub.c.163.com/combk8s/xtrabackup:1.0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on master (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || 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: 200m
            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: hub.c.163.com/combk8s/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 ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we‘re cloning from an existing slave.
            mv xtrabackup_slave_info change_master_to.sql.in
            # Ignore xtrabackup_binlog_info in this case (it‘s useless).
            rm -f 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 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

          # 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"
            # In case of container restart, attempt this at-most-once.
            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

          # 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:
      namespace: blog
      name: data
      annotations:
        volume.beta.kubernetes.io/storage-class: course-nfs-storage
    spec:
      accessModes: ["ReadWriteMany"]
      resources:
        requests:
          storage: 1.5Gi

详细解释看：https://blog.csdn.net/qq_38900565/article/details/102482782?utm_medium=distribute.pc_aggpage_search_result.none-task-blog-2~all~first_rank_v2~rank_v28-12-102482782.nonecase&utm_term=k8s%E9%83%A8%E7%BD%B2mysql&spm=1000.2123.3001.4430

创建成功会显示：

[root@km-1 mysql]# kubectl get statefulset/mysql -n blog -o wide
NAME    READY   AGE   CONTAINERS         IMAGES
mysql   2/2     29h   mysql,xtrabackup   mysql:5.7,hub.c.163.com/combk8s/xtrabackup:1.0

[root@km-1 mysql]# kubectl get pods -lapp=mysql --watch --namespace=blog
NAME      READY   STATUS    RESTARTS   AGE
mysql-0   2/2     Running   9          29h
mysql-1   2/2     Running   7          29h

如果遇到失败，查看日志执行：

kubectl logs -f pod/mysql-0  --all-containers=true -n blog

2、MySQL部署环境验证

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.blog）

kubectl run mysql-client --image=mysql:5.7 -it --rm --restart=Never -- mysql -h mysql-0.mysql.blog

CREATE DATABASE demo;
CREATE TABLE demo.messages (message VARCHAR(250));
INSERT INTO demo.messages VALUES (‘hello‘);

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.blog

写入数据

insert into message values("hello world");

此时会报错 ERROR 1290 (HY000): The MySQL server is running with the --super-read-only option so it cannot execute this statement
这是因为mysql-1是一个只读备库，无法进行写操作。

3、扩缩容

//扩容至5副本
kubectl scale statefulset mysql  --replicas=5
//缩容只2副本
kubectl scale statefulset mysql  --replicas=2

4、 部署对外读服务

apiVersion: v1
kind: Service
metadata:
  namespace: blog
  name: mysql-read
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
    targetPort: 3306
    nodePort: 30036
  type: NodePort
  selector:
    app: mysql

5、部署对外读写服务

[root@k8s-master ~]# kubectl get pods --show-labels -n blog | grep mysql-0 | awk ‘{print $6}‘ | awk -F, ‘{print $3}‘
statefulset.kubernetes.io/pod-name=mysql-0 

得到该标签后写入如下selector字段

apiVersion: v1
kind: Service
metadata:
  namespace: blog
  name: mysql-writeandread
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
    targetPort: 3306
    nodePort: 30006
  selector:
    statefulset.kubernetes.io/pod-name: mysql-0
  type: NodePort

使用集群任意节点IP:nodePort进行连接