1、Keepalived安装：包安装及脚本编译安装

VRRP：虚拟路由冗余协议,解决静态网关单点风险

物理层包括：路由器（主设备、备用设备）、三层交换机（用于连接主备设备）
软件层：keepalived

相关技术：
主备设备连接--心跳线
主备设备优先级
主备设备工作方式：抢占式、非抢占式
主备设备安全认证

工作模式：主备  主主  备主（虚拟路由器2）

LB：负载均衡集群  典型代表：LVS/HAProxy/nginx
HA：高可用集群    典型代表：keepalived实现无状态应用的高可用。mysql、redis等有状态应用通过自身的高可用解决方案 如mysql的组复制、pxc。
HPC：高性能集群

#CentOS 
[root@centos ~]#yum -y install keepalived 
#ubuntu 
[root@ubuntu2004 ~]#apt -y install keepalived

[root@ubuntu2004 ~]#apt -y install keepalived
#默认没有配置文件无法启动
#利用范例生成配置文件
[root@ubuntu2004 ~]#cp /usr/share/doc/keepalived/samples/keepalived.conf.sample /etc/keepalived/keepalived.conf
[root@ubuntu2004 ~]#systemctl start keepalived.service
查看进程
[root@ubuntu2004 ~]#ps auxf |grep keepalived

[root@ubuntu2004 ~]#cat install_keepalived.sh 
#!/bin/bash
KEEPALIVED_VERSION=2.2.7
#KEEPALIVED_VERSION=2.2.2
#KEEPALIVED_VERSION=2.0.20
KEEPALIVED_FILE=keepalived-${KEEPALIVED_VERSION}.tar.gz

KEEPALIVED_INSTALL_DIR=/apps/keepalived
SRC_DIR=/usr/local/src
KEEPALIVED_URL=https://keepalived.org/software/

CPUS=`grep -c processor  /proc/cpuinfo`

. /etc/os-release


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


download_file (){
    cd  ${SRC_DIR}
    if [ $ID = 'centos' -o $ID = 'rocky' ];then
        rpm -q wget &> /dev/null || yum -y install wget 
    elif [ $ID = 'ubuntu' ];then
        dpkg -l |grep wget || { apt update;  apt install -y wget; } 
    else
        color "不支持此操作系统，退出!" 1
        exit
    fi
    if [ ! -e ${KEEPALIVED_FILE} ];then
        wget --no-check-certificate  ${KEEPALIVED_URL}${KEEPALIVED_FILE} 
        [ $? -ne 0 ] && { color "KEEPALIVED源码包下载失败" 1 ; exit; }
    fi
}

install_keepalived () {
    if [ $ID = 'centos' -o $ID = 'rocky' ];then
        yum -y install make gcc ipvsadm autoconf automake openssl-devel libnl3-devel iptables-devel net-snmp-devel glib2-devel pcre2-devel  libmnl-devel systemd-devel &> /dev/null
    elif [ $ID = 'ubuntu' ];then
        apt update 
        apt -y install make gcc ipvsadm build-essential pkg-config automake autoconf libipset-dev libnl-3-dev libnl-genl-3-dev libssl-dev libxtables-dev libip4tc-dev libip6tc-dev libipset-dev libmagic-dev libsnmp-dev libglib2.0-dev libpcre2-dev libnftnl-dev libmnl-dev libsystemd-dev
    else
        color "不支持此操作系统，退出!" 1
    fi
    tar xf ${KEEPALIVED_FILE}
    cd keepalived-${KEEPALIVED_VERSION}
    ./configure --prefix=${KEEPALIVED_INSTALL_DIR} --disable-fwmark
    make -j $CPUS && make install
    if [ $? -eq 0 ];then
        color "KEEPALIVED编译安装成功" 0
    else
        color "KEEPALIVED编译安装失败,退出!" 1
        exit
    fi
    [ -d /etc/keepalived ] || mkdir -p /etc/keepalived
    cp ${KEEPALIVED_INSTALL_DIR}/etc/keepalived/keepalived.conf.sample  /etc/keepalived/keepalived.conf
    cp ./keepalived/keepalived.service /lib/systemd/system/
}

start_keepalived () {
    systemctl daemon-reload
    systemctl enable --now keepalived &> /dev/null 
    systemctl is-active keepalived
    if [ $? -eq 0 ] ;then
        color "Keepalived 服务安装成功!" 0  
    else
        color "Keepalived 服务安装失败!" 1
        exit 1
    fi
}

download_file

install_keepalived

start_keepalived

[root@ubuntu2004 ~]#systemctl status keepalived.service
查看IP
    inet 192.168.200.16/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet 192.168.200.17/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet 192.168.200.18/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe69:a082/64 scope link

ping生成的这些IPping不通，要把配置文件中的vrrp_strict取消掉
[root@ubuntu2004 ~]#ping 192.168.200.16
PING 192.168.200.16 (192.168.200.16) 56(84) bytes of data.
ping: sendmsg: 不允许的操作
[root@ubuntu2004 ~]#vim /etc/keepalived/keepalived.conf
#vrrp_strict
[root@ubuntu2004 ~]#systemctl restart keepalived.service
[root@ubuntu2004 ~]#ping 192.168.200.16
PING 192.168.200.16 (192.168.200.16) 56(84) bytes of data.
64 字节，来自 192.168.200.16: icmp_seq=1 ttl=64 时间=0.027 毫秒