mysql - Kubernetes:从部署转移到有状态集-从 secret 设置环境

Question

Kubernetes文档说，对于mysql Pod，我们需要使用有状态集，以避免当一个Pod死时，换句话说，声明要写入数据的“主”节点，以及该Pod是否出现“裂脑”情况逝世，选出新的主人，这就是为什么我希望将此部署和服务转移到有状态集合的原因:

  ---

    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: mysql-container
    spec:
      replicas: 3
      selector:
        matchLabels:
          app: mysql-container
      template:
        metadata:
          labels:
            app: mysql-container
        spec:
          containers:
          - name: mysql-container
            image: mysql:dev
            imagePullPolicy: "IfNotPresent"
            envFrom:
              - secretRef:
                 name: prod-secrets
            ports:
            - containerPort: 3306
             # container (pod) path
            volumeMounts:
              - name: mysql-persistent-storage
                mountPath: /data/db

          # minikube path
          volumes:
            - name: mysql-persistent-storage
              persistentVolumeClaim:
               claimName: mysql-pvc
            #resources:
            #  requests:
            #    memory: 300Mi
            #    cpu: 400m
            #  limits:
            #    memory: 400Mi
            #    cpu: 500m  
          restartPolicy: Always

---

apiVersion: v1
kind: Service
metadata:
  name: mysql

spec:
  # Open port 3306 only to pods in cluster
  selector:
    app: mysql-container

  ports:
    - name: mysql
      port: 3306
      protocol: TCP
      targetPort: 3306
  type: ClusterIP

我创建了以下状态集: this guide

在容器部分下，我从文件中指定了环境变量，即已移除

 env:
        - name: MYSQL_ALLOW_EMPTY_PASSWORD
          value: "1"

状态集:

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 [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: gcr.io/google-samples/xtrabackup:1.0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on master (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || 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:dev
        imagePullPolicy: "IfNotPresent"
        envFrom:
          - secretRef:
             name: prod-secrets
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        resources:
          #requests:
           # cpu: 300m
           # 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: 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$(<xtrabackup_slave_info)" != "x" ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we're cloning from an existing slave. (Need to remove the tailing semicolon!)
            cat xtrabackup_slave_info | sed -E 's/;$//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
      - name: data
        persistentVolumeClaim:
            claimName: mysql-pvc

服务:

# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
    protocol: TCP
    targetPort: 3306
  type: ClusterIP
  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:
  name: mysql-read
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
    protocol: TCP
    targetPort: 3306
  type: ClusterIP  
  selector:
    app: mysql

我有从中创建 secret 的env文件:

kubectl create secret prod-secrets \
       --from-env-file=env.example 

问题是我无法访问mysql(拒绝访问)，使用 secret 指定的凭据(未设置有状态)的pod都可以正常工作。所有Pod正在运行，日志中无错误

如何在Secretful中指定 secret 值？

我想我需要以某种方式将这些 secret 传递到命令部分，但不知道如何，例如，来自Kuberenets页的示例假定未使用凭据

如果没有更简单的方法来为mysql使用状态集，请告诉我，谢谢。

Answer 1

让我们开始创建一个 secret :

$ kubectl create secret generic test-secret --from-literal=username='my-app' --from-literal=password='39528$vdg7Jb'

$ kubectl get secrets test-secret -o yaml
apiVersion: v1
data:
  password: Mzk1MjgkdmRnN0pi
  username: bXktYXBw
kind: Secret
metadata:
  name: test-secret
  namespace: default

使用envFrom:

使用 envFrom将所有Secret数据定义为容器环境变量。 Secret中的 key成为Pod中的环境 variable名称。 ref

apiVersion: v1
kind: Pod
metadata:
  name: envfrom-secret
  namespace: default
spec:
  containers:
  - name: envars-test-container
    image: nginx
    envFrom:
    - secretRef:
        name: test-secret

检查环境:

$ kubectl exec -it envfrom-secret printenv
.
.
password=39528$vdg7Jb
username=my-app
.
.

使用env:

当您希望某些特定的 key-value对出现在 env列表上，或者您想使用其他名称而不是 env名称设置 key时，可以从k8s env中设置 secret，如下所示:

apiVersion: v1
kind: Pod
metadata:
  name: envfrom-secret
  namespace: default
spec:
  containers:
  - name: envars-test-container
    image: nginx
    env:
    - name: USERNAME
      valueFrom:
        secretKeyRef:
          name: test-secret
          key: username
    - name: PASSWORD
      valueFrom:
        secretKeyRef:
          name: test-secret
          key: password

检查 env:

$  kubectl exec -it envfrom-secret printenv
.
.
USERNAME=my-app
PASSWORD=39528$vdg7Jb
.
.

部署，状态集，守护程序的过程相同。