k8s中使用xtrabackup来实现mysql高可用

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

headless-svc.yaml

apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
  clusterIP: None
  selector:
    app: mysql

statefulSet.yaml

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
        imagePullPolicy: IfNotPresent
        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 [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: twoeo/gcr.io-google-samples-xtrabackup:latest
        imagePullPolicy: IfNotPresent
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on master (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || 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
        imagePullPolicy: IfNotPresent
        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: 50m
            memory: 50Mi
        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: twoeo/gcr.io-google-samples-xtrabackup:latest
        imagePullPolicy: IfNotPresent
        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 <

查看

[root@K8S-M1 xtrabackup]# kubectl get all | grep mysql
pod/mysql-0                                  2/2     Running     5          10h
pod/mysql-1                                  2/2     Running     3          10h
pod/mysql-2                                  2/2     Running     5          9h
service/mysql      ClusterIP       None               3306/TCP        6h31m
statefulset.apps/mysql                   3             3               10h


测试

(master: mysql-0)
[root@K8S-M1 xtrabackup]# kubectl exec -it mysql-0 bash
root@mysql-0:/# mysql
mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| mysql                  |
| performance_schema     |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
5 rows in set (0.12 sec)



(salve:mysql-1)
[root@K8S-M1 xtrabackup]# kubectl exec -it mysql-1 bash
root@mysql-0:/# mysql
mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| mysql                  |
| performance_schema     |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
5 rows in set (0.12 sec)



(salve:mysql-2)
[root@K8S-M1 xtrabackup]# kubectl exec -it mysql-2 bash
root@mysql-0:/# mysql
mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| mysql                  |
| performance_schema     |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
5 rows in set (0.12 sec)

只有master(mysql-0)才有一切操作(读写删....)权限,而salve(mysql-1,mysql-2)只有读的权限
在salve(mysql-1或mysql-2)上操作
mysql> CREATE DATABASE demo; 
ERROR 1290 (HY000): The MySQL server is running with the --super-read-only option so it cannot execute this statement

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

同步操作测试
在master(mysql-0)上操作(创建database,表,插值)

mysql> CREATE DATABASE demo; 
Query OK, 1 row affected (0.04 sec)

mysql> CREATE TABLE demo.messages (message VARCHAR(250)); 
Query OK, 0 rows affected (0.05 sec)

mysql> INSERT INTO demo.messages VALUES ('hello');
Query OK, 1 row affected (0.01 sec)



在salve(mysql-1,mysql-2上操作)
mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| demo                   |
| mysql                  |
| performance_schema     |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
6 rows in set (0.15 sec)

mysql> use demo;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from messages;
+---------+
| message |
+---------+
| hello   |
+---------+
1 row in set (0.00 sec)

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

ok,可以发现同步实现成功。

再创建一个svc来提供对外服务
svc.yaml

# 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

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