OpenShift上部署Redis主从集群

客户有部署有状态服务的需求，单机部署模式相对简单，尝试一下集群部署。

关于Redis的master,slave 以及sentinal的架构和作用不提，有兴趣可以参考之前的博客

https://www.cnblogs.com/ericnie/p/7203950.html

github上参考的文章不少，但很多都需要基于连接互联网进行构建，同时也创建不少的buildconfig,研究了一下，还需要在本地部署一个git.

立刻觉得把问题搞复杂了。所以本文主要以简化为主，说明主要核心步骤，当然也掉到坑里浪费了些时间，不失为一种学习过程吧。

github上参考链接

https://github.com/mjudeikis/redis-openshift

架构

传统的Redis个节点角色和端口

在OpenShift上部署架构图

1.构建镜像

先clone到本地

git clone https://github.com/mjudeikis/redis-openshift

目录结构比较清晰明了，我喜欢

[root@master ~]# tree redis-openshift
redis-openshift
├── image
│   ├── Dockerfile
│   ├── Dockerfile.1
│   ├── epel-7.repo
│   ├── redis-master.conf
│   ├── redis-openshift.tar
│   ├── redis-slave.conf
│   └── run.sh
├── list.yaml
├── openshift
│   ├── build.yaml
│   ├── is-base.yaml
│   ├── is-output.yaml
│   ├── redis-master-dc.yaml
│   ├── redis-master-service.yaml
│   ├── redis-sentinel-dc.yaml
│   ├── redis-sentinel-services.yaml
│   └── redis.yaml
└── README.md

对了，这里我也根据我的环境修改了Dockerfile,主要是yum源的问题

先下载一个放到目录下

http://mirrors.aliyun.com/repo/epel-7.repo，

Dockerfile

FROM rhel7

#RUN yum install epel-release -y
COPY epel-7.repo  /etc/yum.repos.d/epel.repo

RUN yum install redis hostname -y ; yum clean all

COPY redis-master.conf /redis-master/redis.conf
COPY redis-slave.conf /redis-slave/redis.conf
RUN mkdir -p /redis-sentinel ; chmod -R 777 /redis-sentinel /redis-slave
COPY run.sh /run.sh

CMD [ "/run.sh" ]

ENTRYPOINT [ "bash", "-c" ]

比较核心的run文件，我修改成这样

[root@master image]# cat run.sh
#!/bin/bash

# Copyright 2014 The Kubernetes Authors All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

function launchmaster() {
  if [[ ! -e /redis-master-data ]]; then
    echo "Redis master data doesn't exist, data won't be persistent!"
    mkdir /redis-master-data
  fi
  redis-server /redis-master/redis.conf --protected-mode no
}

function launchsentinel() {
  echo "Enter launch sentinel...."
  
   while true; do
    master=$(redis-cli -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1)
    if [[ -n ${master} ]]; then
      master="${master//"}"
    else
      master=$(hostname -i)
    fi

    redis-cli -h ${master} INFO
    if [[ "$?" == "0" ]]; then
      break
    fi
    echo "Connecting to master failed.  Waiting..."
    sleep 10
  done

  sentinel_conf=/redis-sentinel/sentinel.conf

  echo "sentinel monitor mymaster ${master} 6379 2" > ${sentinel_conf}
  echo "sentinel down-after-milliseconds mymaster 60000" >> ${sentinel_conf}
  echo "sentinel failover-timeout mymaster 180000" >> ${sentinel_conf}
  echo "sentinel parallel-syncs mymaster 1" >> ${sentinel_conf}
  echo "bind 0.0.0.0" >> ${sentinel_conf}

  redis-sentinel ${sentinel_conf} --protected-mode no

}

function launchslave() {
  echo "Enter lauch slave....."

   while true; do
    master=$(redis-cli -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1)
    if [[ -n ${master} ]]; then
      master="${master//"}"
    else
      echo "Failed to find master."
      sleep 60
      exit 1
    fi 

    redis-cli -h ${master} INFO
    if [[ "$?" == "0" ]]; then
      break
    fi
    echo "Connecting to master failed.  Waiting..."
    sleep 10
  done
  sed -i "s/%master-ip%/${master}/" /redis-slave/redis.conf
  sed -i "s/%master-port%/6379/" /redis-slave/redis.conf
  redis-server /redis-slave/redis.conf --protected-mode no

}

if [[ "${MASTER}" == "true" ]]; then
  launchmaster
  exit 0
fi

if [[ "${SENTINEL}" == "true" ]]; then
  launchsentinel
  exit 0
fi

launchslave

oc new-project建立一个项目，然后

docker build -t  registry.example.com/openshift/redis-openshift:1.0 .

docker push  registry.example.com/openshift/redis-openshift:1.0

oc import-image redis-openshift:latest --from=registry.example.com/openshift/redis-openshift:1.0  --insecure --confirm

这里必须表扬一下openshift的了，因为在调试过程中我的run.sh改来改去，每次改动需要build镜像，搞完后，直接运行上面三条，就把镜像刷新了

而Openshift的dc的trigger功能发挥作用，每次发现镜像更新后就自动更新，发布新应用，减少大量时间，感觉非常不错！

2.构建一系列的dc和service

修改openshift下的配置文件，确保镜像地址无误。

oc create -f openshift/redis-master-dc.yaml
oc create -f openshift/redis-master-service.yaml

oc create -f openshift/redis-sentinel-dc.yaml
oc create -f openshift/redis-sentinel-services.yaml

oc create -f openshift/redis.yaml

会建立一个master,3个sentinel和3个slave,如图

 进去逐个检查日志，确保成功启动

运行下面命令，查看集群信息。 

redis-cli -h redis-master  info Replication

 构建成功，可以愉快的使用了。

3.集群切换

讲redis-master直接scale到0,模拟down掉

然后检查sentinel的日志，发现mymaster已经从10.129.0.2切换到了10.129.0.8的redis pod.

在reids节点上运行 redis-cli -h 10.129.0.8  info Replication

可以看到集群状态已经发生变化