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【Kubernetes】redisのレプリケーションを実装する方法

投稿日：2020年10月10日

この記事ではKubernetesのDeployment、Serviceについてredisのレプリケーションを実装する実例を交えつつ解説しています。

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はじめに

この記事について

環境

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レプリケーション（Replication）の実装について

レプリケーション（Replication）とは

ReplicationController

Deployment

Service

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実践

$ kubectl cluster-info
Kubernetes master is running at https://192.168.39.7:8443
KubeDNS is running at https://192.168.39.7:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-redis-master
  labels:
    name: deployment-redis-master
spec:
  replicas: 1
  selector:
    matchLabels:
      name: redis-master
  template:
    metadata:
      labels:
        name: redis-master
    spec:
      subdomain: master
      containers:
        - name: redis
          image: redis:3.2.0-alpine
          command:
            - "redis-server"
          args:
            - "--protected-mode"
            - "no"
          ports:
            - containerPort: 6379

$ kubectl apply -f deployment-redis-master.yml
deployment.apps/deployment-redis-master created

$ kubectl get deployment
NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment-redis-master   1/1     1            1           32m
(base) ogihara@ubuntu:~/kubernetes_sample/redis_replication$ kubectl get deployments
NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment-redis-master   1/1     1            1           32m
$ kubectl get rs
NAME                                DESIRED   CURRENT   READY   AGE
deployment-redis-master-5b97f7fd5   1         1         1       32m
$ kubectl get pods
NAME                                      READY   STATUS    RESTARTS   AGE
deployment-redis-master-5b97f7fd5-n8m2b   1/1     Running   0          33m

apiVersion: v1
kind: Service
metadata:
  name: service-redis-master
spec:
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 6379
      targetPort: 6379
      name: redis
  selector:
    name: redis-master

$ kubectl apply -f service-redis-master.yml
service/service-redis-master created

$ kubectl get services
NAME                   TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
kubernetes             ClusterIP      10.96.0.1       <none>        443/TCP          46m
service-redis-master   LoadBalancer   10.104.249.53   <pending>     6379:31584/TCP   19s

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-redis-replica
  labels:
    name: deployment-redis-replica
spec:
  replicas: 2
  selector:
    matchLabels:
      name: redis-replica
  template:
    metadata:
      labels:
        name: redis-replica
    spec:
      subdomain: replica
      containers:
        - name: redis
          image: redis:3.2.0-alpine
          command:
            - "redis-server"
          args:
            - "--slaveof"
            - "service-redis-master.default.svc.cluster.local"
            - "6379"
            - "--protected-mode"
            - "no"
          ports:
            - containerPort: 6379

apiVersion: v1
kind: Service
metadata:
  name: service-redis-replica
spec:
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 6379
      targetPort: 6379
      name: redis
  selector:
    name: redis-replica

$ kubectl apply -f deployment-redis-replica.yml
deployment.apps/deployment-redis-replica created
$ kubectl apply -f service-redis-replica.yml 
service/service-redis-replica created

$ redis-server \
--slaveof service-redis-master.default.svc.cluster.local \
6379 \
--protected-mode no \

$ kubectl get pods
NAME                                       READY   STATUS    RESTARTS   AGE
deployment-redis-master-5b97f7fd5-n8m2b    1/1     Running   0          94m
deployment-redis-replica-89f5664db-vgtrg   1/1     Running   0          2m56s
deployment-redis-replica-89f5664db-zx5kl   1/1     Running   0          2m57s

レプリケーションを確認

$ minikube service --url service-redis-master
http://192.168.39.220:31584
$ $ redis-cli -h 192.168.39.220 -p 31584 info replication
# Replication
role:master
connected_slaves:2
slave0:ip=172.17.0.4,port=6379,state=online,offset=17585,lag=0
slave1:ip=172.17.0.5,port=6379,state=online,offset=17585,lag=1
master_repl_offset:17585
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:17584

$ minikube service --url service-redis-replica
http://192.168.39.220:30251
$ redis-cli -h 192.168.39.220 -p 30251 info replication
# Replication
role:slave
master_host:service-redis-master.default.svc.cluster.local
master_port:6379
master_link_status:up
master_last_io_seconds_ago:4
master_sync_in_progress:0
slave_repl_offset:17739
slave_priority:100
slave_read_only:1
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

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さいごに

参考URL

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