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Kubernetes中部署Redis集群具體步驟
Redis（REmote DIctionary Server的意思）是一個(gè)開源的內(nèi)存數(shù)據(jù)存儲，通常用作數(shù)據(jù)庫、緩存以及消息代理。它可以存儲和操作高級的數(shù)據(jù)結(jié)構(gòu)類型，比如lists、maps、sets以及排序sets。Redis接受多種格式的鍵，因此可以在服務(wù)器上執(zhí)行操作，減少客戶端的工作負(fù)載。
什么是 Redis 集群
Redis Cluster 是一組 Redis 實(shí)例，旨在通過對數(shù)據(jù)庫進(jìn)行分區(qū)來擴(kuò)展數(shù)據(jù)庫，從而使其更具彈性。群集中的每個(gè)成員（無論是主副本還是輔助副本）都管理哈希槽的子集。如果主機(jī)無法訪問，則其從機(jī)將升級為主機(jī)。在由三個(gè)主節(jié)點(diǎn)組成的最小 Redis 群集中，每個(gè)主節(jié)點(diǎn)都有一個(gè)從節(jié)點(diǎn)（以實(shí)現(xiàn)最小的故障轉(zhuǎn)移），每個(gè)主節(jié)點(diǎn)都分配有一個(gè)介于 0 到 16,383 之間的哈希槽范圍。節(jié)點(diǎn) A 包含從 0 到 5000 的哈希槽，節(jié)點(diǎn) B 從 5001 到 10000，節(jié)點(diǎn) C 從 10001 到 16383。群集內(nèi)部的通信是通過內(nèi)部總線進(jìn)行的，使用協(xié)議傳播有關(guān)群集的信息或發(fā)現(xiàn)新節(jié)點(diǎn)。
在 Kubernetes 中部署 Redis 集群
在Kubernetes中部署Redis集群面臨挑戰(zhàn)，因?yàn)槊總€(gè) Redis 實(shí)例都依賴于一個(gè)配置文件，該文件可以跟蹤其他集群實(shí)例及其角色。為此，我們需要結(jié)合使用Kubernetes StatefulSets和PersistentVolumes。
克隆部署文件
git clone https://github.com/llmgo/redis-sts.git
創(chuàng)建 statefulset 類型資源
[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
創(chuàng)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
6379/TCP,16379/TCP 35s
初始化 redis cluster
下一步是形成Redis集群。為此，我們運(yùn)行以下命令并鍵入yes以接受配置。前三個(gè)節(jié)點(diǎn)成為主節(jié)點(diǎn)，后三個(gè)節(jié)點(diǎn)成為從節(jié)點(diǎn)。
$ 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.
驗(yàn)證集群
[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
測試集群
我們想使用集群，然后模擬節(jié)點(diǎn)的故障。對于前一項(xiàng)任務(wù)，我們將部署一個(gè)簡單的 Python 應(yīng)用程序，而對于后者，我們將刪除一個(gè)節(jié)點(diǎn)并觀察集群行為。
部署點(diǎn)擊計(jì)數(shù)器應(yīng)用
我們將一個(gè)簡單的應(yīng)用程序部署到集群中，并在其前面放置一個(gè)負(fù)載平衡器。此應(yīng)用程序的目的是在將計(jì)數(shù)器值作為 HTTP 響應(yīng)返回之前，增加計(jì)數(shù)器并將其存儲在 Redis 集群中。
$ kubectl apply -f app-deployment-service.yml
service/hit-counter-lb created
deployment.apps/hit-counter-app created
在此過程中，如果我們繼續(xù)加載頁面，計(jì)數(shù)器將繼續(xù)增加，并且在刪除Pod之后，我們看到?jīng)]有數(shù)據(jù)丟失。
$ 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.
分享名稱：Kubernetes中部署Redis集群具體步驟
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