k8s部署redis集群搭建过程示例详解

2023-02-21 12:02:09 集群示例搭建

写在前面

在上一篇文章中，我们已经做到了已经创建好6个redis副本了。

具体的详情，可以查看这里：k8s部署redis集群(一)

那么接下来，我们就继续实现redis集群的搭建过程。

一、redis集群搭建

1.1使用redis-cli创建集群

# 查看redis的pod对应的ip
kubectl get pod -n jxbp -o wide
>NAME                             READY   STATUS    RESTARTS   AGE    IP               node         NOMINATED NODE   READINESS GATES
 redis-0                          1/1     Running   0          18h    10.168.235.196   k8s-master   <none>           <none>
 redis-1                          1/1     Running   0          18h    10.168.235.225   k8s-master   <none>           <none>
 redis-2                          1/1     Running   0          18h    10.168.235.239   k8s-master   <none>           <none>
 redis-3                          1/1     Running   0          18h    10.168.235.198   k8s-master   <none>           <none>
 redis-4                          1/1     Running   0          18h    10.168.235.222   k8s-master   <none>           <none>
 redis-5                          1/1     Running   0          18h    10.168.235.238   k8s-master   <none>           <none>
# 进入到redis-0容器
kubectl exec -it redis-0 /bin/bash -n jxbp
# 创建master节点（redis-0、redis-2、redis-4）
redis-cli --cluster create 10.168.235.196:6379 10.168.235.239:6379 10.168.235.222:6379 -a jxbd
    > Warning: Using a passWord with '-a' or '-u' option on the command line interface may not be safe.
    >>> PerfORMing hash slots allocation on 3 nodes...
    Master[0] -> Slots 0 - 5460
    Master[1] -> Slots 5461 - 10922
    Master[2] -> Slots 10923 - 16383
    M: bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 10.168.235.196:6379
       slots:[0-5460] (5461 slots) master
    M: 4367e4a45e557406a3112e7b79f82a44d4ce485e 10.168.235.239:6379
       slots:[5461-10922] (5462 slots) master
    M: a2cec159bbe2efa11a8f60287b90927bcb214729 10.168.235.222:6379
       slots:[10923-16383] (5461 slots) master
    Can I set the above configuration? (type 'yes' to accept): yes
    >>> Nodes configuration updated
    >>> Assign a different config epoch to each node
    >>> Sending CLUSTER MEET messages to join the cluster
    Waiting for the cluster to join
    .
    >>> Performing Cluster Check (using node 10.168.235.196:6379)
    M: bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 10.168.235.196:6379
       slots:[0-5460] (5461 slots) master
    M: a2cec159bbe2efa11a8f60287b90927bcb214729 10.168.235.222:6379
       slots:[10923-16383] (5461 slots) master
    M: 4367e4a45e557406a3112e7b79f82a44d4ce485e 10.168.235.239:6379
       slots:[5461-10922] (5462 slots) master
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.

注意上面的master节点，会生成对应节点id：bcae187137a9b30d7dab8fe0d8ed4a46c6e39638、a2cec159bbe2efa11a8f60287b90927bcb214729、4367e4a45e557406a3112e7b79f82a44d4ce485e，用于创建slave节点。

# 为每个master节点添加slave节点
# 10.168.235.196:6379的位置可以是任意一个master节点,一般我们用第一个master节点即redis-0的ip地址
# --cluster-master-id参数指定该salve节点对应的master节点的id
# -a参数指定redis的密码
# redis-0的master节点，添加redis-1为slave节点
redis-cli --cluster add-node 10.168.235.225:6379 10.168.235.196:6379 --cluster-slave --cluster-master-id bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 -a jxbd
# redis-2的master节点，添加redis-3为slave节点
redis-cli --cluster add-node 10.168.235.198:6379 10.168.235.239:6379 --cluster-slave --cluster-master-id a2cec159bbe2efa11a8f60287b90927bcb214729 -a jxbd
# redis-4的master节点，添加redis-5为slave节点
redis-cli --cluster add-node 10.168.233.238:6379 10.168.235.222:6379 --cluster-slave --cluster-master-id 4367e4a45e557406a3112e7b79f82a44d4ce485e -a jxbd

显示以下信息，即为添加成功：

[OK] All nodes agree about slots configuration.

[OK] All 16384 slots covered.

[OK] New node added correctly.

坑：

一开始是想用headless的域名创建redis集群的，这样节点重启后就不需要更新ip，但是redis不支持使用域名，所以只能绕了一圈又回到固定ip的方法，和容器环境很不协调。

1.2redis集群状态验证（可选）

cluster info

# 进入到redis客户端，集群需要带上-c，有密码需要带上-a
redis-cli -c -a jxbd
# 查看redis集群信息
127.0.0.1:6379> cluster info
cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:3
cluster_current_epoch:3
cluster_my_epoch:1
cluster_stats_messages_ping_sent:7996
cluster_stats_messages_pong_sent:7713
cluster_stats_messages_sent:15709
cluster_stats_messages_ping_received:7710
cluster_stats_messages_pong_received:7996
cluster_stats_messages_meet_received:3
cluster_stats_messages_received:15709

注意：

现在进入集群中的任意一个Pod中都可以访问Redis服务，前面我们创建了一个headless类型的Service，kubernetes集群会为该服务分配一个DNS记录，格式为:$(pod.name).$(headless server.name).${namespace}.svc.cluster.local，每次访问该服务名时，将会直接进入到redis的节点上。svc.cluster.local可省略。例如：

redis-cli -c -a jxbd -h redis-0.redis-hs.jxbp -p 6379

cluster nodes

# 查看redis集群状态
127.0.0.1:6379> cluster nodes
70220b45e978d0cb3Df19b07e55d883b49f4127d 10.168.235.238:6379@16379 slave 4367e4a45e557406a3112e7b79f82a44d4ce485e 0 1670306292673 2 connected
122b89a51a9bf005e3d47b6d721c65621d2e9a75 10.168.235.225:6379@16379 slave bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 0 1670306290558 1 connected
c2afcb9e83038a47d04bf328ead8033788548234 10.168.235.198:6379@16379 slave a2cec159bbe2efa11a8f60287b90927bcb214729 0 1670306291162 3 connected
4367e4a45e557406a3112e7b79f82a44d4ce485e 10.168.235.239:6379@16379 master - 0 1670306291561 2 connected 5461-10922
bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 10.168.235.196:6379@16379 myself,master - 0 1670306291000 1 connected 0-5460
a2cec159bbe2efa11a8f60287b90927bcb214729 10.168.235.222:6379@16379 master - 0 1670306292166 3 connected 10923-16383

可以看到3个master，3个slave节点，都是connected状态。

get，set验证

# 会找到对应的槽进行set操作，去到10.168.235.222节点
set name1 llsydn
-> Redirected to slot [12933] located at 10.168.235.222:6379
OK

# set name1成功
10.168.235.222:6379> set name1 llsydn
OK

# get name1成功
10.168.235.222:6379> get name1
"llsydn"

master节点进行set操作，slave节点复制。主从复制

1.3重启pod,验证集群（可选）

# redis-1未重启之前
10.168.235.239:6379> cluster nodes
4367e4a45e557406a3112e7b79f82a44d4ce485e 10.168.235.239:6379@16379 myself,master - 0 1670307319000 2 connected 5461-10922
bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 10.168.235.196:6379@16379 master - 0 1670307319575 1 connected 0-5460
70220b45e978d0cb3df19b07e55d883b49f4127d 10.168.235.238:6379@16379 slave 4367e4a45e557406a3112e7b79f82a44d4ce485e 0 1670307318000 2 connected
122b89a51a9bf005e3d47b6d721c65621d2e9a75 10.168.235.225:6379@16379 slave bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 0 1670307319781 1 connected
c2afcb9e83038a47d04bf328ead8033788548234 10.168.235.198:6379@16379 slave a2cec159bbe2efa11a8f60287b90927bcb214729 0 1670307319071 3 connected
a2cec159bbe2efa11a8f60287b90927bcb214729 10.168.235.222:6379@16379 master - 0 1670307318000 3 connected 10923-16383

# 重启redis-1
kubectl delete pod redis-1 -n jxbp
pod "redis-1" deleted

# redis-1重启之后
10.168.235.239:6379> cluster nodes
4367e4a45e557406a3112e7b79f82a44d4ce485e 10.168.235.239:6379@16379 myself,master - 0 1670307349000 2 connected 5461-10922
bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 10.168.235.196:6379@16379 master - 0 1670307349988 1 connected 0-5460
70220b45e978d0cb3df19b07e55d883b49f4127d 10.168.235.238:6379@16379 slave 4367e4a45e557406a3112e7b79f82a44d4ce485e 0 1670307349000 2 connected
122b89a51a9bf005e3d47b6d721c65621d2e9a75 10.168.235.232:6379@16379 slave bcae187137a9b30d7dab8fe0d8ed4a46c6e39638 0 1670307350089 1 connected
c2afcb9e83038a47d04bf328ead8033788548234 10.168.235.198:6379@16379 slave a2cec159bbe2efa11a8f60287b90927bcb214729 0 1670307350000 3 connected
a2cec159bbe2efa11a8f60287b90927bcb214729 10.168.235.222:6379@16379 master - 0 1670307348000 3 connected 10923-16383

可以看到重启后的，redis-1节点，虽然ip变了，但是redis集群，还是可以识别到新的ip，集群还是正常的。

10.168.235.225 ---> 10.168.235.232

1.4创建Service服务

前面我们创建了用于实现StatefulSet的Headless Service，但该Service没有Cluster Ip，因此不能用于外界访问。所以，我们还需要创建一个Service，专用于为Redis集群提供访问和负载均衡。

这里可以使用ClusterIP，NodePort。这里，我使用的是NodePort。

vi redis-ss.yaml

---
apiVersion: v1
kind: Service
metadata:
  labels:
    k8s.kuboard.cn/layer: db
    k8s.kuboard.cn/name: redis
  name: redis-ss
  namespace: jxbp
spec:
  ports:
    - name: imdgss
      port: 6379
      protocol: tcp
      targetPort: 6379
      nodePort: 6379
  selector:
    k8s.kuboard.cn/layer: db
    k8s.kuboard.cn/name: redis
  type: NodePort

创建名称为：redis-ss的服务。

在K8S集群中暴露6379端口，并且会对labels name为k8s.kuboard.cn/name: redis的pod进行负载均衡。

然后在K8S集群中，就可以通过redis-ss:6379，对redis集群进行访问。

kubectl get service -n jxbp

>NAME            TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                                                         AGE
redis-hs        ClusterIP   None            <none>        6379/TCP                                                        76m
redis-ss        NodePort    10.96.54.201    <none>        6379:6379/TCP                                                   2s

1.5 springboot项目配置

spring.redis.cluster.nodes=redis-ss:6379

1.6相关疑问分析

至此，大家可能会疑惑，那为什么没有使用稳定的标志，Redis Pod也能正常进行故障转移呢？这涉及了Redis本身的机制。因为，Redis集群中每个节点都有自己的NodeId（保存在自动生成的nodes.conf中），并且该NodeId不会随着IP的变化和变化，这其实也是一种固定的网络标志。也就是说，就算某个Redis Pod重启了，该Pod依然会加载保存的NodeId来维持自己的身份。我们可以在NFS上查看redis-0的nodes.conf文件：

vi /opt/nfs/pv1/nodes.conf
> f6d4993467a4ab1f3fa806f1122edd39f6466394 10.168.235.228:6379@16379 slave ebed24c8fca9ebc16ceaaee0c2bc2e3e09f7b2c0 0 1670316449064 2 connected
ebed24c8fca9ebc16ceaaee0c2bc2e3e09f7b2c0 10.168.235.240:6379@16379 myself,master - 0 1670316450000 2 connected 5461-10922
955e1236652c2fcb11f47c20a43149dcd1f1f92b 10.168.235.255:6379@16379 master - 0 1670316449565 1 connected 0-5460
574c40485bb8f6cfaf8618d482efb06f3e323f88 10.168.235.224:6379@16379 slave 955e1236652c2fcb11f47c20a43149dcd1f1f92b 0 1670316449000 1 connected
91bd3dc859ce51f1ed0e7cbd07b13786297bd05b 10.168.235.237:6379@16379 slave fe0b74c5e461aa22d4d782f891b78ddc4306eed4 0 1670316450672 3 connected
fe0b74c5e461aa22d4d782f891b78ddc4306eed4 10.168.235.253:6379@16379 master - 0 1670316450068 3 connected 10923-16383
vars currentEpoch 3 lastVoteEpoch 0

如上，第一列为NodeId，稳定不变；第二列为IP和端口信息，可能会改变。

这里，我们介绍NodeId的两种使用场景：

当某个Slave Pod断线重连后IP改变，但是Master发现其NodeId依旧，就认为该Slave还是之前的Slave。

当某个Master Pod下线后，集群在其Slave中选举重新的Master。待旧Master上线后，集群发现其NodeId依旧，会让旧Master变成新Master的slave。

对于这两种场景，大家有兴趣的话还可以自行测试，注意要观察Redis的日志。

redis这种有状态的应用到底应不应该使用k8s部署，还是使用外部服务器部署redis集群？

以上就是k8s部署redis集群搭建过程示例详解的详细内容，更多关于k8s部署redis集群的资料请关注其它相关文章！

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