keepalived基础

lvs官方提供了几种lvs高可用构建方案，如下：常用keepalived

http://www.linuxvirtualserver.org/HighAvailability.html

The following examples of building highly available LVS systems are only for reference.

简介

lvs本身不探测后端rs的健康性，由ldirectd辅助完成

lvs本身不保证自己的高可用，结合keepalived的vvrp虚拟路由冗余协议实现高可用

keepalived作用：

保证lvs的高可用
探测后端节点的健康性，并实现节点动态增删
通过配置keepalived，即可实现ipvs规则的配置管理
keepalived支持多种方法探测后端节点
- 四层端口
- 七层http/https头部
- 其他http报文内容
- 支持调用外部自定义脚本进行探测

vrrp协议

vvrp：virtual router redundancy protocol 虚拟路由冗余协议，本意用来保证路由的高可用，实现逻辑：多个路由节点组成一个虚拟路由节点，某一刻，只有一个主节点起作用，但主节点和其他从节点会不断进行通信，告诉它们朕一日不死，你们都是太子，当主节点挂掉时，其他从节点会争抢出新的主节点，周而复始，从而这个虚拟路由节点就有了高可用的属性！

keepalived程序架构

checkers：检测后端rs的健康状态，支持多种方法
- tcp
- http
- https
- misc自定义脚本
ipvs wrapper：该组件用于管理ipvs规则
system all：提供自定义脚本调用的功能
vvrp stack：管理vvrp协议的实现
netlink reflector：管理监控vvrp的 vip地址
watch dog：监控程序

编译安装

yum可以直接安装；

源码安装，官方文档

下为编译安装过程：

1、下载源码包，解压，安装依赖包，编译工具

[root@lvs ~]# yum install -y openssl-devel gcc gcc++
[root@lvs ~]# tar -xf keepalived-1.2.19.tar.gz
[root@lvs ~]# cd keepalived-1.2.19
[root@lvs keepalived-1.2.19]# pwd
/root/keepalived-1.2.19

2、三步走

[root@lvs keepalived-1.2.19]# ./configure --prefix=/usr/local/keepalived-1.2.19

[root@lvs keepalived-1.2.19]# make && make install

[root@lvs keepalived-1.2.19]# ln -sv /usr/local/keepalived-1.2.19/ /usr/local/keepalived
‘/usr/local/keepalived’ -> ‘/usr/local/keepalived-1.2.19/’
# 做软链接方便，版本切换；

3、安装后配置:配置path变量和manpath路径

[root@lvs keepalived-1.2.19]# echo "export PATH=/usr/local/keepalived/bin:$PATH" >> /etc/profile.d/keepalived.sh
[root@lvs keepalived-1.2.19]# source !$
source /etc/profile.d/keepalived.sh

[root@lvs keepalived-1.2.19]# echo "MANPATH /usr/local/keepalived/share/man" >> /etc/man.config
[root@lvs keepalived-1.2.19]# man keepalived.conf

4、安装后目录结构

[root@lvs keepalived]# pwd
/usr/local/keepalived
[root@lvs keepalived]# ll  ./*
./bin:
total 44
-rwxr-xr-x 1 root root 43752 Sep 10 17:18 genhash

# bin下有个genhash，健康检测后端rs页面时，用status_code或genhash命令生成的hash值判断检查结果

./etc:
total 0
drwxr-xr-x 3 root root 44 Sep 10 17:18 keepalived
# 主配置，以及参考模版
drwxr-xr-x 3 root root 20 Sep 10 17:18 rc.d
# 服务启动脚本
drwxr-xr-x 2 root root 24 Sep 10 17:18 sysconfig
# 服务脚本启动时读取的参数文件

./sbin:
total 196
-rwx------ 1 root root 200248 Sep 10 17:18 keepalived

# 主程序

./share:
total 0
drwxr-xr-x 5 root root 42 Sep 10 17:18 man
# man手册，有 1 5 8 三个章节，有keepalived.conf和genhash的配置手册说明

5、准备服务脚本、服务脚本参数文件、配置文件，并做适当修改

[root@lvs keepalived]# cp etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
# 将自带的服务脚本复制到init.d目录下

# 修改服务脚本
# 将daemon后的keepalived改为编译安装的主程序文件路径，如下：
[root@lvs keepalived]# vim /etc/rc.d/init.d/keepalived 
......
start() {
    echo -n $"Starting $prog: "
    daemon /usr/local/keepalived/sbin/keepalived ${KEEPALIVED_OPTIONS}
    RETVAL=$?
    echo
    [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$prog
}



# 添加开启启动项，并设置为开启启动
[root@lvs keepalived]# chkconfig --add keepalived
[root@lvs keepalived]# chkconfig keepalived on


# 复制自带的服务脚本参数文件，到/etc/sysconfig目录下
[root@lvs keepalived]# cp etc/sysconfig/keepalived /etc/sysconfig/   


# 复制自带的配置文件到，对应目录
[root@lvs keepalived]# mkdir /etc/keepalived
[root@lvs keepalived]# cp etc/keepalived/keepalived.conf /etc/keepalived/
[root@lvs keepalived]# ll /etc/keepalived/keepalived.conf

ps: 复制自带配置文件到哪个目标路径？自带的服务脚本里指明了默认路径，如下：

#!/bin/sh
#
# Startup script for the Keepalived daemon
#
# processname: keepalived
# pidfile: /var/run/keepalived.pid
# config: /etc/keepalived/keepalived.conf
# chkconfig: - 21 79
# description: Start and stop Keepalived

# Source function library
. /etc/rc.d/init.d/functions

# Source configuration file (we set KEEPALIVED_OPTIONS there)
. /etc/sysconfig/keepalived

ps：配置sysconfig文件，可以自定义keepalived程序读取的配置文件，从而不使用默认的配置文件

keepalived简介与安装

keepalived基础

简介

vrrp协议

keepalived程序架构

编译安装

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