Redis 介绍
Redis 代表REmote DIctionary Server是一种开源的内存中数据存储，通常用作数据库，缓存或消息代理。它可以存储和操作高级数据类型，例如列表，地图，集合和排序集合。由于Redis接受多种格式的密钥，因此可以在服务器上执行操作，从而减少了客户端的工作量。它仅将磁盘用于持久性，而将数据库完全保存在内存中。Redis是一种流行的数据存储解决方案，并被GitHub，Pinterest，Snapchat，Twitter，*，Flickr等技术巨头所使用。
为什么使用 Redis
它的速度非常快。它是用 ANSI C 编写的，并且可以在 POSIX 系统上运行，例如 Linux，Mac OS X 和 Solaris。
Redis 通常被排名为最流行的键/值数据库和最流行的与容器一起使用的 NoSQL 数据库。
其缓存解决方案减少了对云数据库后端的调用次数。
应用程序可以通过其客户端 API 库对其进行访问。
所有流行的编程语言都支持 Redis。
它是开源且稳定的。
什么是 Redis 集群
Redis Cluster 是一组 Redis 实例，旨在通过对数据库进行分区来扩展数据库，从而使其更具弹性。群集中的每个成员（无论是主副本还是辅助副本）都管理哈希槽的子集。如果主机无法访问，则其从机将升级为主机。在由三个主节点组成的最小 Redis 群集中，每个主节点都有一个从节点（以实现最小的故障转移），每个主节点都分配有一个介于 0 到 16,383 之间的哈希槽范围。节点 A 包含从 0 到 5000 的哈希槽，节点 B 从 5001 到 10000，节点 C 从 10001 到 16383。群集内部的通信是通过内部总线进行的，使用协议传播有关群集的信息或发现新节点。
在 Kubernetes 中部署 Redis 集群
在Kubernetes中部署Redis集群面临挑战，因为每个 Redis 实例都依赖于一个配置文件，该文件可以跟踪其他集群实例及其角色。为此，我们需要结合使用Kubernetes StatefulSets和PersistentVolumes。
克隆部署文件
git?clone?https://github.com/llmgo/redis-sts.git
创建 statefulset 类型资源
[root@node01?redis-sts]#?cat?redis-sts.yml?
---
apiVersion:?v1
kind:?ConfigMap
metadata:
??name:?redis-cluster
data:
??update-node.sh:?|
????#!/bin/sh
????REDIS_NODES="/data/nodes.conf"
????sed?-i?-e?"/myself/?s/[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}/${POD_IP}/"?${REDIS_NODES}
????exec?"$@"
??redis.conf:?|+
????cluster-enabled?yes
????cluster-require-full-coverage?no
????cluster-node-timeout?15000
????cluster-config-file?/data/nodes.conf
????cluster-migration-barrier?1
????appendonly?yes
????protected-mode?no
---
apiVersion:?apps/v1
kind:?StatefulSet
metadata:
??name:?redis-cluster
spec:
??serviceName:?redis-cluster
??replicas:?6
??selector:
????matchLabels:
??????app:?redis-cluster
??template:
????metadata:
??????labels:
????????app:?redis-cluster
????spec:
??????containers:
??????-?name:?redis
????????image:?redis:5.0.5-alpine
????????ports:
????????-?containerPort:?6379
??????????name:?client
????????-?containerPort:?16379
??????????name:?gossip
????????command:?["/conf/update-node.sh",?"redis-server",?"/conf/redis.conf"]
????????env:
????????-?name:?POD_IP
??????????valueFrom:
????????????fieldRef:
??????????????fieldPath:?status.podIP
????????volumeMounts:
????????-?name:?conf
??????????mountPath:?/conf
??????????readOnly:?false
????????-?name:?data
??????????mountPath:?/data
??????????readOnly:?false
??????volumes:
??????-?name:?conf
????????configMap:
??????????name:?redis-cluster
??????????defaultMode:?0755
??volumeClaimTemplates:
??-?metadata:
??????name:?data
????spec:
??????accessModes:?[?"ReadWriteOnce"?]
??????resources:
????????requests:
??????????storage:?5Gi
??????storageClassName:?standard
$?kubectl?apply?-f?redis-sts.yml
configmap/redis-cluster?created
statefulset.apps/redis-cluster?created
$?kubectl?get?pods?-l?app=redis-cluster
NAME??????????????READY???STATUS????RESTARTS???AGE
redis-cluster-0???1/1?????Running???0??????????53s
redis-cluster-1???1/1?????Running???0??????????49s
redis-cluster-2???1/1?????Running???0??????????46s
redis-cluster-3???1/1?????Running???0??????????42s
redis-cluster-4???1/1?????Running???0??????????38s
redis-cluster-5???1/1?????Running???0??????????34s
创建 service
[root@node01?redis-sts]#?cat?redis-svc.yml??? ---?? apiVersion:?v1?? kind:?Service?? metadata:?? ??name:?redis-cluster?? spec:?? ??type:?ClusterIP?? ??clusterIP:?10.96.0.100?? ??ports:?? ??-?port:?6379?? ????targetPort:?6379?? ????name:?client?? ??-?port:?16379?? ????targetPort:?16379?? ????name:?gossip?? ??selector:?? ????app:?redis-cluster?? $?kubectl?apply?-f?redis-svc.yml?? service/redis-cluster?created?? $?kubectl?get?svc?redis-cluster?? NAME????????????TYPE????????CLUSTER-IP???EXTERNAL-IP???PORT(S)??????????????AGE?? redis-cluster???ClusterIP???10.96.0.100
初始化 redis cluster
“下一步是形成Redis集群。为此，我们运行以下命令并键入yes以接受配置。前三个节点成为主节点，后三个节点成为从节点。
$?kubectl?exec?-it?redis-cluster-0?--?redis-cli?--cluster?create?--cluster-replicas?1?$(kubectl?get?pods?-l?app=redis-cluster?-o?jsonpath=‘{range.items[*]}{.status.podIP}:6379?‘)??
??
>>>?Performing?hash?slots?allocation?on?6?nodes...??
Master[0]?->?Slots?0?-?5460??
Master[1]?->?Slots?5461?-?10922??
Master[2]?->?Slots?10923?-?16383??
Adding?replica?10.244.2.11:6379?to?10.244.9.19:6379??
Adding?replica?10.244.9.20:6379?to?10.244.6.10:6379??
Adding?replica?10.244.8.15:6379?to?10.244.7.8:6379??
M:?00721c43db194c8f2cacbafd01fd2be6a2fede28?10.244.9.19:6379??
???slots:[0-5460]?(5461?slots)?master??
M:?9c36053912dec8cb20a599bda202a654f241484f?10.244.6.10:6379??
???slots:[5461-10922]?(5462?slots)?master??
M:?2850f24ea6367de58fb50e632fc56fe4ba5ef016?10.244.7.8:6379??
???slots:[10923-16383]?(5461?slots)?master??
S:?554a58762e3dce23ca5a75886d0ccebd2d582502?10.244.8.15:6379??
???replicates?2850f24ea6367de58fb50e632fc56fe4ba5ef016??
S:?20028fd0b79045489824eda71fac9898f17af896?10.244.2.11:6379??
???replicates?00721c43db194c8f2cacbafd01fd2be6a2fede28??
S:?87e8987e314e4e5d4736e5818651abc1ed6ddcd9?10.244.9.20:6379??
???replicates?9c36053912dec8cb20a599bda202a654f241484f??
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?10.244.9.19:6379)??
M:?00721c43db194c8f2cacbafd01fd2be6a2fede28?10.244.9.19:6379??
???slots:[0-5460]?(5461?slots)?master??
???1?additional?replica(s)??
M:?9c36053912dec8cb20a599bda202a654f241484f?10.244.6.10:6379??
???slots:[5461-10922]?(5462?slots)?master??
???1?additional?replica(s)??
S:?87e8987e314e4e5d4736e5818651abc1ed6ddcd9?10.244.9.20:6379??
???slots:?(0?slots)?slave??
???replicates?9c36053912dec8cb20a599bda202a654f241484f??
S:?554a58762e3dce23ca5a75886d0ccebd2d582502?10.244.8.15:6379??
???slots:?(0?slots)?slave??
???replicates?2850f24ea6367de58fb50e632fc56fe4ba5ef016??
S:?20028fd0b79045489824eda71fac9898f17af896?10.244.2.11:6379??
???slots:?(0?slots)?slave??
???replicates?00721c43db194c8f2cacbafd01fd2be6a2fede28??
M:?2850f24ea6367de58fb50e632fc56fe4ba5ef016?10.244.7.8:6379??
???slots:[10923-16383]?(5461?slots)?master??
???1?additional?replica(s)??
[OK]?All?nodes?agree?about?slots?configuration.??
>>>?Check?for?open?slots...??
>>>?Check?slots?coverage...??
[OK]?All?16384?slots?covered.
验证集群
[root@node01?redis-sts]#?kubectl?exec?-it?redis-cluster-0?--?redis-cli?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:6?? cluster_my_epoch:1?? cluster_stats_messages_ping_sent:16?? cluster_stats_messages_pong_sent:22?? cluster_stats_messages_sent:38?? cluster_stats_messages_ping_received:17?? cluster_stats_messages_pong_received:16?? cluster_stats_messages_meet_received:5?? cluster_stats_messages_received:38?? [root@node01?redis-sts]#?for?x?in?$(seq?0?5);?do?echo?"redis-cluster-$x";?kubectl?exec?redis-cluster-$x?--?redis-cli?role;?echo;?done?? redis-cluster-0?? master?? 14?? 10.244.2.11?? 6379?? 14?? ?? redis-cluster-1?? master?? 28?? 10.244.9.20?? 6379?? 28?? ?? redis-cluster-2?? master?? 28?? 10.244.8.15?? 6379?? 28?? ?? redis-cluster-3?? slave?? 10.244.7.8?? 6379?? connected?? 28?? ?? redis-cluster-4?? slave?? 10.244.9.19?? 6379?? connected?? 14?? ?? redis-cluster-5?? slave?? 10.244.6.10?? 6379?? connected?? 28
测试集群
我们想使用集群，然后模拟节点的故障。对于前一项任务，我们将部署一个简单的 Python 应用程序，而对于后者，我们将删除一个节点并观察集群行为。
部署点击计数器应用
我们将一个简单的应用程序部署到集群中，并在其前面放置一个负载平衡器。此应用程序的目的是在将计数器值作为 HTTP 响应返回之前，增加计数器并将其存储在 Redis 集群中。
$?kubectl?apply?-f?app-deployment-service.yml?? service/hit-counter-lb?created?? deployment.apps/hit-counter-app?created
在此过程中，如果我们继续加载页面，计数器将继续增加，并且在删除Pod之后，我们看到没有数据丢失。
$??curl?`kubectl?get?svc?hit-counter-lb?-o?json|jq?-r?.spec.clusterIP`?? I?have?been?hit?20?times?since?deployment.?? $??curl?`kubectl?get?svc?hit-counter-lb?-o?json|jq?-r?.spec.clusterIP`?? I?have?been?hit?21?times?since?deployment.?? $?curl?`kubectl?get?svc?hit-counter-lb?-o?json|jq?-r?.spec.clusterIP`?? I?have?been?hit?22?times?since?deployment.?? $?kubectl?delete?pods?redis-cluster-0?? pod?"redis-cluster-0"?deleted?? $?kubectl?delete?pods?redis-cluster-1?? pod?"redis-cluster-1"?deleted?? $??curl?`kubectl?get?svc?hit-counter-lb?-o?json|jq?-r?.spec.clusterIP`?? I?have?been?hit?23?times?since?deployment.
参考文档
[redis-cluster集群配置1] http://llmgo.cn/post/redis-003/
[redis-cluster集群配置2] http://www.yunweipai.com/36338.html
[Redis集群 cluster-slot操作指令] https://blog.csdn.net/shuyun123456789/article/details/60868718
原文链接：http://tinyurl.com/vpihglin
文章转自：?奇妙的Linux世界
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