MySQL8.0.28在k8s上使用xtrabackup进行复制

Question

问题

我想在k8s上使用xtrabackup进行MySQL8.0.28的复制。基于运行良好的k8s官方示例(稍后我将在本文中讨论)，我为MySQL8.0.28复制创建了k8s集群(在官方示例中，Note为5.7 )。但不起作用。我的yaml文件是

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: mysql-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  storageClassName: mysql-sc
  local:
    path: /tmp
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - controlplane
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv-2
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  storageClassName: mysql-sc
  local:
    path: /tmp
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - node01
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql
  labels:
    app: mysql
    app.kubernetes.io/name: mysql
data:
  my.cnf: |
    [mysqld]
    !includedir /etc/mysql/conf.d/
  primary.cnf: |
    # Apply this config only on the primary.
    [mysqld]
    log-bin
    gtid_mode=ON
    enforce_gtid_consistency=ON
  replica.cnf: |
    # Apply this config only on replicas.
    [mysqld]
    gtid_mode=ON
    enforce_gtid_consistency=ON
    super-read-only
    log_bin=OFF
---
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
    app.kubernetes.io/name: 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 primary: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
  name: mysql-read
  labels:
    app: mysql
    app.kubernetes.io/name: mysql
    readonly: "true"
spec:
  ports:
  - name: mysql
    port: 3306
  selector:
    app: mysql
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
      app.kubernetes.io/name: mysql
  serviceName: mysql
  replicas: 2
  template:
    metadata:
      labels:
        app: mysql
        app.kubernetes.io/name: mysql
    spec:
      initContainers:
      - name: init-mysql
        image: mysql:8.0.28
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Generate mysql server-id from pod ordinal index.
          [[ `uname -n` =~ -([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 my.cnf file from config-map to conf-2 volume(emptyDir).
          cp /mnt/config-map/my.cnf /mnt/conf-2/
          # Copy appropriate conf.d files from config-map to emptyDir.
          if [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/primary.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/replica.cnf /mnt/conf.d/
          fi          
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: conf-2
          mountPath: /mnt/conf-2
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: hiroaki2020/dtuj_xtrabackup:1.0
        securityContext:
          runAsUser: 0
          runAsGroup: 0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on primary (ordinal index 0).
          [[ `uname -n` =~ -([0-9]+)$ ]] || 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
        - name: conf-2
          mountPath: /etc/mysql
      containers:
      - name: mysql
        image: mysql:8.0.28
        resources:
          limits:
            memory: 512Mi
            cpu: 500m
          requests:
            memory: 128Mi
            cpu: 100m
        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
        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: hiroaki2020/dtuj_xtrabackup:1.0
        securityContext:
          runAsUser: 0
          runAsGroup: 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$(<xtrabackup_slave_info)" != "x" ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we're cloning from an existing replica. (Need to remove the tailing semicolon!)
            cat xtrabackup_slave_info | sed -E 's/;$//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 primary. Parse binlog position.
            [[ `cat xtrabackup_binlog_info` =~ ^([^.]*\.[0-9]+)[[:space:]]+([0-9]+) ]] || 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
        - name: conf-2
          mountPath: /etc/mysql
        resources:
          limits:
            cpu: 500m
            memory: 512Mi
          requests:
            cpu: 100m
            memory: 100Mi
      volumes:
      - name: conf
        emptyDir: {}
      - name: conf-2
        emptyDir: {}
      - name: config-map
        configMap:
          name: mysql
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: mysql-sc
      resources:
        requests:
          storage: 5Gi

在上面的yaml文件中，我更改了mysql映像版本，并根据下面的Dockerfile使用了名为“hiroaki2020 2020/dtuj_xtrabackup:1.0”的原始映像。

FROM percona/percona-xtrabackup:8.0.28
LABEL maintainer="hiroaki"

RUN microdnf update && \
    rm -rf /var/cache/yum && \
    microdnf -y install nmap-ncat shadow-utils && \
    groupadd --system -g 27 mysql && \
    useradd --system -s /usr/bin/false -g mysql -u 27 -c mysql --no-create-home --home-dir /nonexistent mysql && \
    microdnf -y remove shadow-utils && \
    microdnf clean all

USER mysql

此映像基于xtrabackup映像，其版本与mysql的版本相对应(=8.0.28)。我还添加了ncat并将用户更改为mysql，但为了使其简单，请通过设置k8s securityContext将其更改为securityContext清单文件中的根用户。

我将上面的k8s清单文件应用于k8s操场，但是当第二个mysql吊舱(= mysql -1)启动时，更确切地说，当克隆-mysql容器在第二个吊舱中工作时，第一个mysql荚中的xtra备份容器会出现类似的错误。

Ncat: assertion failed: count <= INT_MAX QUITTING.

我怎么才能解决这个问题？

k8s官方示例，它运行良好的

正如我所说，上面的清单文件是基于k8s官方示例的。在本例中，我成功地在k8s上运行，但mysql为5.7。比较可能有助于解决问题，因此我提供了这个示例的简单步骤。

第一步

打开k8s游乐场并登录。在上面的k8s官方示例链接中有到它的链接。这个官方的例子可能适用于其他操场或本地PC上的k8s，如minikube，但我不确定。

第二步

vim k8s.yaml

然后粘贴这个。

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: mysql-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv
spec:
  capacity:
    storage: 1Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  storageClassName: mysql-sc
  local:
    path: /tmp
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - controlplane
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv-2
spec:
  capacity:
    storage: 1Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  storageClassName: mysql-sc
  local:
    path: /tmp
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - node01
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql
  labels:
    app: mysql
    app.kubernetes.io/name: mysql
data:
  primary.cnf: |
    # Apply this config only on the primary.
    [mysqld]
    log-bin    
  replica.cnf: |
    # Apply this config only on replicas.
    [mysqld]
    super-read-only    
---
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
    app.kubernetes.io/name: 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 primary: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
  name: mysql-read
  labels:
    app: mysql
    app.kubernetes.io/name: mysql
    readonly: "true"
spec:
  ports:
  - name: mysql
    port: 3306
  selector:
    app: mysql
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
      app.kubernetes.io/name: mysql
  serviceName: mysql
  replicas: 2
  template:
    metadata:
      labels:
        app: mysql
        app.kubernetes.io/name: mysql
    spec:
      initContainers:
      - name: init-mysql
        image: mysql:5.7
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Generate mysql server-id from pod ordinal index.
          [[ `uname -n` =~ -([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 [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/primary.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/replica.cnf /mnt/conf.d/
          fi          
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: gcr.io/google-samples/xtrabackup:1.0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on primary (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || 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
        resources:
          limits:
            memory: 512Mi
            cpu: 300m
          requests:
            memory: 64Mi
            cpu: 50m
        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
        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: gcr.io/google-samples/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$(<xtrabackup_slave_info)" != "x" ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we're cloning from an existing replica. (Need to remove the tailing semicolon!)
            cat xtrabackup_slave_info | sed -E 's/;$//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 primary. 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:
          limits:
            cpu: 300m
            memory: 512Mi
          requests:
            cpu: 100m
            memory: 100Mi
      volumes:
      - name: conf
        emptyDir: {}
      - name: config-map
        configMap:
          name: mysql
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: mysql-sc
      resources:
        requests:
          storage: 1Gi

我创建了本地持久卷和存储类，并对正式示例做了一些修改以使其工作，例如将脚本中的"hostname“cmd更改为"uname -n”等等。

第三步

跑

kubectl apply -f k8s.yaml

好了。等待豆荚准备就绪，然后在MySQL0pod中输入mysql容器，并向mysql客户端添加一些记录。您可以看到数据被正确地复制到副本服务器。

Answer 1

我将k8s平台从基尔科达游乐场切换到了迷你库，我还将ncat改为最新版本，并增加了对mysql容器的资源分配，现在mysql集群正常工作。