kubernetes实战-基于redis和docker的留言簿案例，kubernetesredis
kubernetes实战-基于redis和docker的留言簿案例，kubernetesredis
一、介绍 本案例基于Kubernetes和Docker，其中包括1、web前端 2、redis master 3、redis slave 其中web前端通过javascript redis api和redis master交互
kubernetes体系架构
二、配置 0、先决条件 Kubernetes 集群
1、启动redis master 使用replication controller确保只有一个pod在运行（当某个节点down了，rc会在另一个健康的node启动redis master），但可能会有数据丢失。
验证master运行成功，如下展示了pod运行在centos2/192.168.1.112这台机器上[root@centos1 example]# kubectl create -f redis-master-controller.jsonreplicationcontrollers/redis-master[root@centos1 example]# kubectl get rcCONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICASredis-master master redis name=redis-master 1
SSH到centos2/192.168.1.112查看docker状态[root@centos1 example]# kubectl get podsPOD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGEredis-master-svar7 172.17.0.9 centos2/192.168.1.112 name=redis-master Running 55 secondsmaster redis Running 55 seconds
注意：kubectl create执行后，如果镜像不存在，会执行docker pull，根据网络情况，下载中的pods 在kubertnetes UI上会显示pending状态[root@centos2 yum.repos.d]# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES91689ce56668 redis:latest "/entrypoint.sh redi 3 minutes ago Up 3 minutes k8s_master.52732b08_redis-master-svar7_default_5b6d5485-1894-11e5-b3ad-000c293c8c19_97e79b7b38c3180813c3 gcr.io/google_containers/pause:0.8.0 "/pause" 3 minutes ago Up 3 minutes k8s_POD.49eee8c2_redis-master-svar7_default_5b6d5485-1894-11e5-b3ad-000c293c8c19_298e038f
2、启动master service 一个kubernetes service会对一个或多个container进行负载均衡，这是通过我们上面redis-master中定义的labels元数据实现的，值得注意的是，在redis中只有一个master，但是我们依然为它创建一个service，这是因为这样我们就能使用一个elastic IP来路由到具体某一个master。 kubernetes集群中的service是通过container中的环境变量实现服务发现的，service基于pod label实现container的负载均衡。 在第一步中创建的pod包含了一个label“name=redis-master”，service的selector字段决定了service将流量转发给哪个pod，port和targetPort信息定义了service proxy运行在什么端口。
上面的运行成功后，所有pods都能发现redis master运行在6379端口，从salve到master流量走向会有以下两步： 1、一个redis slave会连接到redis master service的port上 2、流量会从service节点上的port到targetPort 如果targetPort未指定，默认和port一致[root@centos1 example]# kubectl create -f redis-master-service.jsonservices/redis-master[root@centos1 example]# kubectl get servicesNAME LABELS SELECTOR IP(S) PORT(S)redis-master name=redis-master name=redis-master 10.254.154.90 6379/TCP
3、启动replicated slave pod 虽然redis master是一个单独的pod，redis slaves是一个replicated pod，在Kubernetes中，一个Replication Controller负责管理一个replicated pod的多个实例，RC会自动拉起down掉的replica（可以通过杀死docker 进程方式简单测试）
可以看到一个master pod和两个slave pod[root@centos1 example]# kubectl create -f redis-slave-controller.jsonreplicationcontrollers/redis-slave[root@centos1 example]# kubectl get rcCONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICASredis-master master redis name=redis-master 1redis-slave slave kubernetes/redis-slave:v2 name=redis-slave 2[root@centos1 example]# kubectl get podsPOD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGEredis-master-svar7 172.17.0.9 centos2/192.168.1.112 name=redis-master Running 41 minutesmaster redis Running 41 minutesredis-slave-31tkb 172.17.0.10 centos2/192.168.1.112 name=redis-slave Running 29 secondsslave kubernetes/redis-slave:v2 Running 28 secondsredis-slave-uk8nu 172.17.0.11 centos2/192.168.1.112 name=redis-slave Running 29 secondsslave kubernetes/redis-slave:v2 Running 28 seconds
4、启动slave service 和master一样，我们希望有一个代理服务连接到redis slave，除了服务发现之外，slave service还为web app client提供了透明代理。 这次service 的selector是name=redis-slave，我们可以方便的使用kubectl get services -l "label=value"命令来定位这些服务
[root@centos1 example]# kubectl create -f redis-slave-service.jsonservices/redis-slave[root@centos1 example]# kubectl get servicesNAME LABELS SELECTOR IP(S) PORT(S)redis-master name=redis-master name=redis-master 10.254.154.90 6379/TCPredis-slave name=redis-slave name=redis-slave 10.254.159.145 6379/TCP
5、创建frontend pod 这是一个简单的PHP 服务，用来和master service（写请求）或slave service（读请求）交互
运行成功后，查看当前pod运行状态[root@centos1 example]# kubectl create -f frontend-controller.jsonreplicationcontrollers/frontend[root@centos1 example]# kubectl get rcCONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICASfrontend php-redis kubernetes/example-guestbook-php-redis:v2 name=frontend 3redis-master master redis name=redis-master 1redis-slave slave kubernetes/redis-slave:v2 name=redis-slave 2
可以看到一个redis master，两个redis slave和三个frontend pods[root@centos1 example]# kubectl get podsPOD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGEfrontend-fr5z1 172.17.0.13 centos2/192.168.1.112 name=frontend Running 2 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 2 minutesfrontend-gjx3t 172.17.0.14 centos2/192.168.1.112 name=frontend Running 2 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 2 minutesfrontend-v608r 172.17.0.12 centos2/192.168.1.112 name=frontend Running 2 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 2 minutesredis-master-svar7 172.17.0.9 centos2/192.168.1.112 name=redis-master Running 53 minutesmaster redis Running 53 minutesredis-slave-31tkb 172.17.0.10 centos2/192.168.1.112 name=redis-slave Running 12 minutesslave kubernetes/redis-slave:v2 Running 12 minutesredis-slave-uk8nu 172.17.0.11 centos2/192.168.1.112 name=redis-slave Running 12 minutesslave kubernetes/redis-slave:v2 Running 12 minutes
6、创建guestbook service 和其他service一样，你可以创建一个service管理frontend pods
我们可以通过frontend service（10.254.154.111）访问pods，但是这个IP明显是无法在外部访问的，下一节讲解如何在外部网络访问guestbook[root@centos1 example]# kubectl create -f frontend-service.jsonservices/frontend[root@centos1 example]# kubectl get servicesNAME LABELS SELECTOR IP(S) PORT(S)frontend name=frontend name=frontend 10.254.154.111 80/TCPredis-master name=redis-master name=redis-master 10.254.154.90 6379/TCPredis-slave name=redis-slave name=redis-slave 10.254.159.145 6379/TCP
7、外部网络访问guestbook kubernetes 支持两种访问暴露一个服务到外部IP地址
NodePorts
和LoadBalancers，https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/services.md#external-services
另外可以查看防火墙，找到service对应的端口，如下
发现redis-master是在10.254.154.90上，登录到centos2上，执行iptables-save，发现其中有这样一条规则[root@centos1 example]# kubectl get pods,servicesPOD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGEfrontend-fr5z1 172.17.0.13 centos2/192.168.1.112 name=frontend Running 22 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 22 minutesfrontend-gjx3t 172.17.0.14 centos2/192.168.1.112 name=frontend Running 22 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 22 minutesfrontend-v608r 172.17.0.12 centos2/192.168.1.112 name=frontend Running 22 minutesphp-redis kubernetes/example-guestbook-php-redis:v2 Running 22 minutesredis-master-svar7 172.17.0.9 centos2/192.168.1.112 name=redis-master Running About an hourmaster redis Running About an hourredis-slave-31tkb 172.17.0.10 centos2/192.168.1.112 name=redis-slave Running 32 minutesslave kubernetes/redis-slave:v2 Running 32 minutesredis-slave-uk8nu 172.17.0.11 centos2/192.168.1.112 name=redis-slave Running 32 minutesslave kubernetes/redis-slave:v2 Running 32 minutesNAME LABELS SELECTOR IP(S) PORT(S)frontend name=frontend name=frontend 10.254.154.111 80/TCPkubernetes component=apiserver,provider=kubernetes <none> 10.254.0.2 443/TCPkubernetes-ro component=apiserver,provider=kubernetes <none> 10.254.0.1 80/TCPredis-master name=redis-master name=redis-master 10.254.154.90 6379/TCPredis-slave name=redis-slave name=redis-slave 10.254.159.145 6379/TCP[root@centos1 example]# kubectl get servicesNAME LABELS SELECTOR IP(S) PORT(S)frontend name=frontend name=frontend 10.254.154.111 80/TCPkubernetes component=apiserver,provider=kubernetes <none> 10.254.0.2 443/TCPkubernetes-ro component=apiserver,provider=kubernetes <none> 10.254.0.1 80/TCPredis-master name=redis-master name=redis-master 10.254.154.90 6379/TCPredis-slave name=redis-slave name=redis-slave 10.254.159.145 6379/TCP
-A KUBE-PORTALS-HOST -d 10.254.154.90/32 -p tcp -m comment --comment "default/redis-master:" -m tcp --dport 6379 -j DNAT --to-destination 192.168.1.112:49038[root@centos2 yum.repos.d]# redis-cli -p 49038127.0.0.1:49038> set a bOK127.0.0.1:49038> get a"b"
8、使用curl简单测试 提交数据
curl "localhost:8000/index.php?cmd=set&key=messages&value=jay_sais_hi"curl "localhost:8000/index.php?cmd=get&key=messages"附本案例用到的6个.json文件 1、redis-master-controller.json
2、redis-master-service.json{"kind":"ReplicationController","apiVersion":"v1beta3","metadata":{"name":"redis-master","labels":{"name":"redis-master"}},"spec":{"replicas":1,"selector":{"name":"redis-master"},"template":{"metadata":{"labels":{"name":"redis-master"}},"spec":{"containers":[{"name":"master","image":"redis","ports":[{"containerPort":6379}]}]}}}}
3、redis-slave-controller.json{"kind":"Service","apiVersion":"v1beta3","metadata":{"name":"redis-master","labels":{"name":"redis-master"}},"spec":{"ports": [{"port":6379,"targetPort":6379}],"selector":{"name":"redis-master"}}}
4、redis-slave-service.json{"kind":"ReplicationController","apiVersion":"v1beta3","metadata":{"name":"redis-slave","labels":{"name":"redis-slave"}},"spec":{"replicas":2,"selector":{"name":"redis-slave"},"template":{"metadata":{"labels":{"name":"redis-slave"}},"spec":{"containers":[{"name":"slave","image":"kubernetes/redis-slave:v2","ports":[{"containerPort":6379}]}]}}}}
5、frontend-controller.json{"kind":"Service","apiVersion":"v1beta3","metadata":{"name":"redis-slave","labels":{"name":"redis-slave"}},"spec":{"ports": [{"port":6379}],"selector":{"name":"redis-slave"}}}
6、frontend-service.json{"kind":"ReplicationController","apiVersion":"v1beta3","metadata":{"name":"frontend","labels":{"name":"frontend"}},"spec":{"replicas":3,"selector":{"name":"frontend"},"template":{"metadata":{"labels":{"name":"frontend"}},"spec":{"containers":[{"name":"php-redis","image":"kubernetes/example-guestbook-php-redis:v2","ports":[{"containerPort":80}]}]}}}}
{"kind":"Service","apiVersion":"v1beta3","metadata":{"name":"frontend","labels":{"name":"frontend"}},"spec":{"ports": [{"port":80}],"selector":{"name":"frontend"}}}
评论暂时关闭