1烂叔、簡(jiǎn)述redis集群的實(shí)現(xiàn)原理

• 開(kāi)啟cluster功能的redis節(jié)點(diǎn)間愤估，通過(guò)使用ping機(jī)制互通并通告自己的hash slots畅哑，通過(guò)Gossip協(xié)議通告各自所知的其他node的信息旭绒，然后建立連接。

• 集群中某個(gè)節(jié)點(diǎn)是否失效是通過(guò)集群中超過(guò)半數(shù)節(jié)點(diǎn)的探測(cè)都失效來(lái)決定的京痢，因此為了避免出現(xiàn)腦裂（偶數(shù)節(jié)點(diǎn)之間是否sdown的投票出現(xiàn)均分）奶甘，redis cluster的Master節(jié)點(diǎn)最少數(shù)目是3個(gè)

• redis集群支持16384個(gè)hash slot，存儲(chǔ)key時(shí)祭椰，crc16校驗(yàn)算法根據(jù)key值計(jì)算出校驗(yàn)值臭家，然后取模16384，得到的結(jié)果落在0-16383之間的某個(gè)slot上方淤，集群中的Master節(jié)點(diǎn)會(huì)分配0-16383中某一段范圍的slot钉赁，key會(huì)根據(jù)slot存儲(chǔ)在對(duì)應(yīng)的Master節(jié)點(diǎn)上。

• 由于每個(gè)Master節(jié)點(diǎn)都只存儲(chǔ)一定范圍內(nèi)的slot臣淤，因此存在slot的單點(diǎn)故障橄霉，需要通過(guò)主從復(fù)制實(shí)現(xiàn)Master節(jié)點(diǎn)的高可用；但集群復(fù)制只能支持一層邑蒋，不支持樹(shù)形復(fù)制結(jié)構(gòu)，也不支持級(jí)聯(lián)復(fù)制按厘；

• 客戶端通過(guò)跨集群命令医吊，將key寫入到集群的任意節(jié)點(diǎn)，節(jié)點(diǎn)根據(jù)計(jì)算得到key對(duì)應(yīng)的slot逮京，判斷如果slot指向自身卿堂，則直接執(zhí)行命令；否則節(jié)點(diǎn)會(huì)返回客戶端MOVED重定向懒棉，客戶端將命令重定向發(fā)送給目標(biāo)節(jié)點(diǎn)草描。

2、基于redis5的redis cluster部署

按照如下腳本策严，完成1,2項(xiàng)redis的安裝和配置：

#!/bin/bash
#****************************************************************************************#
#Author:                        Yabao11
#QQ:                            what QQ穗慕，no QQ
#Date:                          2022-01-04
#FileName:                      nginx.sh
#URL:                           https://github.com/yabao11
#Description:                   Test Script
#Copyright (C):                 2022 All rights reserved
#*******************************定義顏色*************************************************#
RED="\e[1;31m"
GREEN="\e[1;32m"
SKYBLUE="\e[1;36m"
YELLOW="\e[1;43m"
BLUE="\e[1;44m"
END="\e[0m"
RandomColor="\e[1;32m"
#****************************************************************************************#
function Ostype {
    if grep -i -q "release 6" /etc/centos-release;then
      echo Centos6
    elif grep -i -q Centos-8 /etc/os-release;then
      echo Centos
    elif grep -i -q Centos-7 /etc/os-release;then
      echo Centos7
    elif grep -i -q Ubuntu /etc/os-release;then
      echo Ubuntu
    elif grep -i -q "RedHat" /etc/os-release;then
      echo Redhat
    fi
}

function color {
  RES_COL=60
  MOVE_TO_COL="echo -en \E[${RES_COL}G"
  SETCOLOR_SUCCESS="echo -en \E[1;32m"
  SETCOLOR_FAILURE="echo -en \E[1;31m"
  SETCOLOR_WARNING="echo -en \E[1;33m"
  SETCOLOR_NORMAL="echo -en \E[0m"
  echo -n "$1" && $MOVE_TO_COL
  echo -n "["
  if [[ $2 = "success" || $2 = "0" ]]; then
    ${SETCOLOR_SUCCESS}
    echo -n "  OK  "
  elif [[ $2 = "failure" || $2 = "1" ]]; then
    ${SETCOLOR_FAILURE}
    echo -n "FAILED"
  else
    ${SETCOLOR_WARNING}
    echo -n "WARNING"
  fi
  ${SETCOLOR_NORMAL}
  echo -n "]"
  echo
}

function redis_install {
    echo -e $GREEN"關(guān)閉selinux..."$END
    setenforce 0
    sed -i.bak -r 's|SELINUX=enforcing|SELINUX=disabled|' /etc/selinux/config
    systemctl disable --now firewalld && color "firewalld已關(guān)閉" 0
    yum  -y install gcc jemalloc-devel systemd-devel wget || { color "編譯軟件安裝失敗妻导！" 1;exit; }
    [ -e /root/${redis_version}.tar.gz ] || wget http://download.redis.io/releases/${redis_version}.tar.gz -P /root/
    tar xvf ${redis_version}.tar.gz || { color "文件解壓失敗" 1;exit; }
    cd ${redis_version}
    make USE_SYSTEMD=yes PREFIX=${redis_path} install > /dev.null && color "安裝成功" 0 || color "安裝失敗逛绵，檢查配置參數(shù)" 1
    echo 'PATH=/data/redis/bin:$PATH' > /etc/profile.d/redis.sh
    . /etc/profile.d/redis.sh
    id redis || ( useradd -r -s /sbin/nologin redis && color "新增用戶redis" 0 || color "用戶redis新建失敗" 1 )
    mkdir /data/redis/{etc,log,data,run}
    { cp redis.conf ${redis_path}/etc/;cp sentinel.conf ${redis_path}/etc/; } && color "配置文件復(fù)制完成" 0
    chown -R redis.redis ${redis_path} && color "文件權(quán)限修改完畢" 0 || color "文件權(quán)限修改失敗" 1
    cat >> /etc/sysctl.conf <<EOF
net.core.somaxconn = 1024
vm.overcommit_memory = 1
EOF
    sysctl -p && color "全連接隊(duì)列和內(nèi)存超額分配內(nèi)核參數(shù)修改完成" 0 || color "內(nèi)核參數(shù)修改失敗" 1
    echo never > /sys/kernel/mm/transparent_hugepage/enabled && color "關(guān)閉THP（透明大頁(yè)）" 0 || "關(guān)閉THP失敗" 1
    echo 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' >> /etc/rc.d/rc.local
    chmod +x /etc/rc.d/rc.local
    [ -e /lib/systemd/system/redis@.service ] && rm -rf /lib/systemd/system/redis@.service
    cat > /lib/systemd/system/redis@.service <<EOF
[Unit]
Description=Redis persistent key-value database
After=network.target

[Service]
ExecStart=${redis_path}/bin/redis-server ${redis_path}/etc/%i.conf --supervised systemd
#ExecStop=/usr/libexec/redis-shutdown
ExecStop=/bin/kill -s QUIT \$MAINPID
Type=notify
User=redis
Group=redis
RuntimeDirectory=redis
RuntimeDirectoryMode=0755

[Install]
WantedBy=multi-user.target
EOF
    systemctl daemon-reload
    systemctl enable --now redis@redis
}

function redis_config {
    sed -i.bak -r -e 's/(^bind\s).*/\10.0.0.0/' \
    -e 's/daemonize no/daemonize yes/' \
    -e 's|^pidfile.*|pidfile '${redis_path}'/run/redis.pid|' \
    -e 's|^logfile.*|logfile '${redis_path}'/log/redis.log|' \
    -e 's|^dir.*|dir '${redis_path}'/data|' \
    ${redis_path}/etc/redis.conf && color "redis.conf配置文件修改完畢怀各！" 0
    systemctl restart redis@redis
}

function redis_slave {
    while true;do
        read -p "是否需要將當(dāng)前節(jié)點(diǎn)配置為slave節(jié)點(diǎn)？" askuser1
        askuser1=`echo $askuser1 | tr 'A-Z' 'a-z'`
        case $askuser1 in
        y|yes)
            read -p "輸入主節(jié)點(diǎn)IP地址：" slaveip
            if [ -z ${slaveip} ];then
                while [ -z ${slaveip} ];do
                    read -p "請(qǐng)輸入主節(jié)點(diǎn)IP地址：" slaveip
                done
            fi
            echo "replicaof ${slaveip} 6379" >>  /data/redis/etc/redis.conf && color "redis.conf配置文件修改完畢术浪！" 0
            systemctl restart redis@redis && color "服務(wù)重啟完成瓢对！" 0
            break
        ;;
        n|no)
            break
        ;;
        *)
            inputerror
            continue
        ;;
        esac
    done
}

function sentinel_config {
    read -p "輸入主節(jié)點(diǎn)IP地址：" masterip
    if [ -z ${masterip} ];then
        while [ -z ${masterip} ];do
            read -p "請(qǐng)輸入主節(jié)點(diǎn)IP地址：" masterip
        done
    fi
    sed -i.bak -r -e '/#\s+bind\s+127.0.0.1/ibind 0.0.0.0' \
    -e 's|^daemonize.*|daemonize yes|' \
    -e 's|^logfile.*|logfile '${redis_path}'/log/redis-sentinel.log|' \
    -e 's|^sentinel\smonitor\smymaster.*|sentinel monitor mymaster '${masterip}' 6379 2|' \
    -e 's|^sentinel\sdown-after-milliseconds.*|sentinel down-after-milliseconds mymaster 3000|' \
    ${redis_path}/etc/sentinel.conf && color "sentinel配置文件修改成功！" 0
    cat > /lib/systemd/system/redis-sentinel.service <<EOF
[Unit]
Description=Redis Sentinel
After=network.target

[Service]
ExecStart=${redis_path}/bin/redis-sentinel ${redis_path}/etc/sentinel.conf --supervised systemd
ExecStop=/bin/kill -s QUIT \$MAINPID
User=redis
Group=redis
Type=notify
RuntimeDirectory=redis
RuntimeDirectoryMode=0755

[Install]
WantedBy=multi-user.target
EOF
    systemctl daemon-reload
    systemctl restart redis-sentinel.service
}

    read -p "請(qǐng)輸入希望安裝的redis版本胰苏，回車使用默認(rèn)版本：redis-6.2.6" redis
    read -p "請(qǐng)輸入希望安裝的redis路徑硕蛹，回車使用默認(rèn)路徑：/data/redis" predis
    redis_version=${redis:-redis-6.2.6}
    redis_path=${predis:-/data/redis}

#exec
PS3="請(qǐng)選擇您要執(zhí)行的操作！："
MENU="
安裝redis
配置redis
配置為從節(jié)點(diǎn)
配置sentinel
退出
"
select M in $MENU ;do
    case $REPLY in
        1)
            redis_install
        ;;
        2)
            redis_config
        ;;
        3)
            redis_slave
        ;;
        4)
            sentinel_config
        ;;
        *)
        exit
        ;;
    esac
done

開(kāi)啟cluster

sed -i.bak -e 's/bind 127.0.0.1/bind 0.0.0.0/' \
-e '/# cluster-enabled yes/a cluster-enabled yes' \
-e '/# cluster-config-file nodes-6379.conf/a cluster-config-file /data/redis/etc/nodes-6379.conf' \
-e '/cluster-require-full-coverage yes/c cluster-require-full-coverage no' /data/redis/etc/redis.conf

使用redis-cli創(chuàng)建cluster

redis-cli --cluster create 192.168.32.187:6379 192.168.32.188:6379 192.168.32.189:6379 <<EOF
yes
EOF

#6臺(tái)機(jī)器的主備部署參考如下配置硕并，前三臺(tái)是master妓美，后三臺(tái)一一對(duì)應(yīng)前三臺(tái)作為slave，同時(shí)hash slot也會(huì)均勻分布到三臺(tái)master
#redis-cli --cluster create 10.0.0.8:6379 10.0.0.18:6379 10.0.0.28:6379 10.0.0.38:6379 10.0.0.48:6379 10.0.0.58:6379 --cluster-replicas 1

結(jié)果確認(rèn)

[root@centos8mini ~]# redis-cli cluster nodes
a9576816037f5f6f103def47473ce8a63c095e9e 192.168.32.188:6379@16379 master - 0 1644374438466 2 connected 5461-10922
df7e0425f345c1bc494c350be88cb1d73acb1932 192.168.32.187:6379@16379 myself,master - 0 1644374434000 1 connected 0-5460
4054278384642524b50caa222820b77fd51f02b0 192.168.32.189:6379@16379 master - 0 1644374437446 3 connected 10923-16383
[root@centos8mini ~]# redis-cli cluster info
cluster_state:ok
cluster_slots_assigned:16384  #分配的hash slot
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:3  #3個(gè)節(jié)點(diǎn)
cluster_size:3  #3臺(tái)master
cluster_current_epoch:3
cluster_my_epoch:1
cluster_stats_messages_ping_sent:78
cluster_stats_messages_pong_sent:73
cluster_stats_messages_sent:151
cluster_stats_messages_ping_received:71
cluster_stats_messages_pong_received:78
cluster_stats_messages_meet_received:2
cluster_stats_messages_received:151

[root@centos8mini ~]# redis-cli -c set k1 v1
OK
[root@centos8mini ~]# redis-cli -c set k2 v2
OK
[root@centos8mini ~]# redis-cli -c set k3 v2
OK
[root@centos8mini ~]# redis-cli -c set k3 v3
OK
[root@centos8mini ~]# redis-cli -c get k1
"v1"
[root@centos8mini ~]# redis-cli -c get k2
"v2"
[root@centos8mini ~]# redis-cli -c get k3
"v3"

[root@centos8mini ~]# redis-cli --cluster info 192.168.32.187:6379
192.168.32.187:6379 (df7e0425...) -> 3 keys | 5461 slots | 0 slaves.
192.168.32.188:6379 (a9576816...) -> 1 keys | 5462 slots | 0 slaves.
192.168.32.189:6379 (40542783...) -> 2 keys | 5461 slots | 0 slaves.
[OK] 6 keys in 3 masters.
0.00 keys per slot on average.