本文主要通过利用k8s如何部署Redis,来学习使用k8s的存储卷Volume。

Pod本⾝具有⽣命周期，故其内部运⾏的容器及其相关数据⾃⾝均⽆法持久存在。Kubernetes也⽀持类似Docker的存储卷功能，不过，其存储卷Volume是与Pod资源绑定⽽⾮容器。

Pod Volume

如何要在一个Pod里声明 Volume：

  1. ⼀是通过.spec.volumes字段定义在Pod之上的存储卷列表，其⽀持使⽤多种不同类型的存储卷且配置参数差别很⼤；
spec:
…
volumes:
* name: logdata
emptyDir: {}
* name: example
gitRepo:
repository: https://github.com/iKubernetes/k8s_book.git
revision: master
directory: .
  1. 另⼀个是通过.spec.containers.volumeMounts字段在容器上定义的存储卷挂载列表，它只能挂载当前Pod资源中定义的具体存储卷，当然，也可以不挂载任何存储卷
spec:
…
containers:
* name: <String>
…
volumeMounts:
* name <string> -required-
mountPath <string> -required-

在之前（声明式对象配置）有介绍过nginx的部署，接着来部署Redis，和Nginx有所不同的是，这里多了一个 ConfigMap 和Volume ,用来配置管理redis和储存。

环境

  • 一个k8s 集群（mater* 1，node* 1）
  • 一个正常连接k8smater的主机的终端

创建 Config-Map

使用 ConfigMap 来配置 Redis ，包含了Redis配置文件里需要的配置项，在创建Pod时会作为配置文件挂载到应用所在的容器中。 my-config-map.yaml 具体如下：

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-redis-config
  namespace: my-ns
data:
  redis.conf: |
    requirepass 123456
    protected-mode no
    port 6379
    tcp-backlog 511
    timeout 0
    tcp-keepalive 300
    daemonize no
    supervised no
    pidfile /var/run/redis_6379.pid
    loglevel notice
    logfile ""
    databases 16
    always-show-logo yes
    save 900 1
    save 300 10
    save 60 10000
    stop-writes-on-bgsave-error yes
    rdbcompression yes
    rdbchecksum yes
    dbfilename dump.rdb
    dir /data
    slave-serve-stale-data yes
    slave-read-only yes
    repl-diskless-sync no
    repl-diskless-sync-delay 5
    repl-disable-tcp-nodelay no
    slave-priority 100
    lazyfree-lazy-eviction no
    lazyfree-lazy-expire no
    lazyfree-lazy-server-del no
    slave-lazy-flush no
    appendonly no
    appendfilename "appendonly.aof"
    appendfsync everysec
    no-appendfsync-on-rewrite no
    auto-aof-rewrite-percentage 100
    auto-aof-rewrite-min-size 64mb
    aof-load-truncated yes
    aof-use-rdb-preamble no
    lua-time-limit 5000
    slowlog-log-slower-than 10000
    slowlog-max-len 128
    latency-monitor-threshold 0
    notify-keyspace-events Ex
    hash-max-ziplist-entries 512
    hash-max-ziplist-value 64
    list-max-ziplist-size -2
    list-compress-depth 0
    set-max-intset-entries 512
    zset-max-ziplist-entries 128
    zset-max-ziplist-value 64
    hll-sparse-max-bytes 3000
    activerehashing yes
    client-output-buffer-limit normal 0 0 0
    client-output-buffer-limit slave 256mb 64mb 60
    client-output-buffer-limit pubsub 32mb 8mb 60
    hz 10
    aof-rewrite-incremental-fsync yes

执行命令

# kubectl apply -f my-redis-config.yaml

创建 Deployment

创建Deployment 作为调度Pod运行 Redis 的载体。my-redis-deployment.yaml具体如下

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-redis # Unique name for the deployment
  namespace: my-ns
  labels:
    app: my-redis       # Labels to be applied to this deployment
spec:
  selector:
    matchLabels:     # This deployment applies to the Pods matching these labels
      app: my-redis
      role: master
      tier: backend
  replicas: 1        # Run a single pod in the deployment
  template:          # Template for the pods that will be created by this deployment
    metadata:
      labels:        # Labels to be applied to the Pods in this deployment
        app: my-redis
        role: master
        tier: backend
    spec:            # Spec for the container which will be run inside the Pod.
      containers:
        - name: my-redis
          image: redis
          resources:
            requests:
              cpu: 100m
              memory: 100Mi
#          command: ["redis-server","/etc/redis/redis.conf"]
          command:
            - redis-server
            - /etc/redis/redis.conf
          ports:
            - containerPort: 6379
          volumeMounts:
            - name: my-redis-config
              mountPath: /etc/redis/redis.conf
              subPath: redis.conf
            - name: my-redis-storage
              mountPath: /data
      volumes:
        - name: my-redis-storage
          emptyDir: {}
        - name: my-redis-config
          configMap:
            name: my-redis-config
            items:
              - key: redis.conf
                path: redis.conf

执行

# kubectl apply -f my-redis-deployment.yaml

创建 service

NodePort 方式向外暴露服务。my-redis-service.yaml 具体如下

apiVersion: v1
kind: Service        # Type of Kubernetes resource
metadata:
  name: my-redis-svc # Name of the Kubernetes resource
  namespace: my-ns
  labels:            # Labels that will be applied to this resource
    app: my-redis
    role: master
    tier: backend
spec:
  type: NodePort
  ports:
    - port: 6379       # Map incoming connections on port 6379 to the target port 6379 of the Pod
      targetPort: 6379
      nodePort: 30379
  selector:          # Map any Pod with the specified labels to this service
    app: my-redis
    role: master
    tier: backend

执行

# kubectl apply -f my-redis-service.yaml

测试

redis-client 测试NodeId:NodePort

redis-cli -h YourNodeIp -p 30379 -a 123456
YourNodeIp:30379> info
# Server
redis_version:7.0.4
...

连接成功。

参考