一、简介
Keepalived是一个免费开源的,用C编写的类似于layer3, 4 & 7交换机制软件,具备我们平时说的第3层、第4层和第7层交换机的功能。主要提供loadbalancing(负载均衡)和 high-availability(高可用)功能,负载均衡实现需要依赖Linux的虚拟服务内核模块(ipvs),而高可用是通过VRRP协议实现多台机器之间的故障转移服务。
Keepalived体系结构
上图是Keepalived的功能体系结构,大致分两层:用户空间(user space)和内核空间(kernel space)。
内核空间:主要包括IPVS(IP虚拟服务器,用于实现网络服务的负载均衡)和NETLINK(提供高级路由及其他相关的网络功能)两个部份。
用户空间:
WatchDog:负载监控checkers和VRRP进程的状况
VRRP Stack:负载负载均衡器之间的失败切换FailOver,如果只用一个负载均稀器,则VRRP不是必须的。
Checkers:负责真实服务器的健康检查healthchecking,是keepalived最主要的功能。换言之,可以没有VRRP Stack,但健康检查healthchecking是一定要有的。
IPVS wrapper:用户发送设定的规则到内核ipvs代码
Netlink Reflector:用来设定vrrp的vip地址等。
Keepalived的所有功能是配置keepalived.conf文件来实现的。
二、安装与配置
从官网下载keepalived的最新版本,本文以当前最新版本1.2.24为例。
2.1 安装
shell> cd /usr/local/src shell> wget http://www.keepalived.org/software/keepalived-1.2.24.tar.gz shell> tar -zxvf keepalived-1.2.24.tar.gz shell> cd keepalived-1.2.24 shell> ./configure --prefix=/usr/local/keepalived shell> make && make install
2.2 配置
安装完成后,进入安装目录的etc目录下,将keepalived相应的配置文件拷贝到系统相应的目录当中。keepalived启动时会从/etc/keepalived目录下查找keepalived.conf配置文件,如果没有找到则使用默认的配置。/etc/keepalived目录安装时默认是没有安装的,需要手动创建。配置文件目录结构如下所示:
shell> tree -l /usr/local/keepalived/etc -- keepalived | |-- keepalived.conf | `-- samples | |-- keepalived.conf.status_code | |-- keepalived.conf.track_interface | |-- keepalived.conf.vrrp | |-- 。。。 |-- rc.d | `-- init.d | `-- keepalived `-- sysconfig `-- keepalived
分别对应系统目录(忽略samples目录):
/etc/keepalived/keepalived.conf /etc/rc.d/init.d/keepalived /etc/sysconfig/keepalived
将配置文件拷贝到系统对应的目录下:
shell> mkdir /etc/keepalived shell> cp /usr/local/keepalived/etc/keepalived.conf /etc/keepalived/keepalived.conf shell> cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/keepalived shell> cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived
设置keepalived服务开机启动:
shell> chkconfig keepalived on shell> service keepalived start #启动服务 shell> service keepalived stop #停止服务 shell> service keepalived restart #重启服务
另外需要注意的一点是,keepalived启动时不会检查配置文件的语法是否正确,所以我们在编写配置文件时要特别小心,别写错了,否则会出现一些意想不到的现象。
使用service keepalived start命令启动服务时,默认会将/etc/sysconfig/keepalived文件中KEEPALIVED_OPTIONS参数作为keepalived服务启动时的参数,并从/etc/keepalived/目录下加载keepalived.conf配置文件,或用-f参数指定配置文件的位置。
# Options for keepalived. See `keepalived --help' output and keepalived(8) and # keepalived.conf(5) man pages for a list of all options. Here are the most # common ones : # # --vrrp -P Only run with VRRP subsystem. # --check -C Only run with Health-checker subsystem. # --dont-release-vrrp -V Dont remove VRRP VIPs & VROUTEs on daemon stop. # --dont-release-ipvs -I Dont remove IPVS topology on daemon stop. # --dump-conf -d Dump the configuration data. # --log-detail -D Detailed log messages.日志默认输出在/var/log/message文件中 # --log-facility -S 0-7 Set local syslog facility (default=LOG_DAEMON) # KEEPALIVED_OPTIONS="-D"
运行keepalived --help可以查看启动时的可选参数,这些可选参数都可以配置在/etc/sysconfig/keepalived文件中的KEEPALIVED_OPTIONS选项中,作为服务启动时的参数。
keepalived正常运行后,会启动3个进程,其中一个是父进程,负责监控其子进程。一个是vrrp子进程,另外一个是checkers子进程。
shell> ps -ef | grep keepalived root 831 1 0 11:22 ? 00:00:00 keepalived -D root 840 831 0 11:22 ? 00:00:00 keepalived -D root 841 831 0 11:22 ? 00:00:00 keepalived -D
到此keepalived就安装完成了。
三、Keeplive配置文件详解
第一部分:全局定义块
1、email通知。作用:有故障,发邮件报警。
2、Lvs负载均衡器标识(lvs_id)。在一个网络内,它应该是唯一的。
3、花括号“{}”。用来分隔定义块,因此必须成对出现。如果写漏了,keepalived运行时,不会得到预期的结果。由于定义块内存在嵌套关系,因此很容易遗漏结尾处的花括号,这点要特别注意。
global_defs { notification_email { #指定keepalived在发生切换时需要发送email到的对象,一行一个 [email protected] } notification_email_from [email protected] #指定发件人 smtp_server localhost #指定smtp服务器地址 smtp_connect_timeout 30 #指定smtp连接超时时间 router_id LVS_DEVEL #运行keepalived机器的一个标识 }
第二部分:vrrp_sync_group作用
确定失败切换(FailOver)包含的路由实例个数。即在有2个负载均衡器的场景,一旦某个负载均衡器失效,需要自动切换到另外一个负载均衡器的实例是哪些? 实例组group{}至少包含一个vrrp实例
vrrp_sync_group VG_1{ #监控多个网段的实例 group { VI_1 #实例名 VI_2 ...... } notify_master /path/xx.sh #指定当切换到master时,执行的脚本 netify_backup /path/xx.sh #指定当切换到backup时,执行的脚本 notify_fault "path/xx.sh VG_1" #故障时执行的脚本 notify /path/xx.sh smtp_alert #使用global_defs中提供的邮件地址和smtp服务器发送邮件通知 }
第三部分:vrrp_instance,实例名出自实例组group所包含的那些名字。
vrrp_instance VI_1 { state BACKUP #指定那个为master,那个为backup,如果设置了nopreempt这个值不起作用,主备考priority决 定 interface eth0 #设置实例绑定的网卡 dont_track_primary #忽略vrrp的interface错误(默认不设置) track_interface{ #设置额外的监控,里面那个网卡出现问题都会切换 eth0 eth1 } mcast_src_ip #发送多播包的地址,如果不设置默认使用绑定网卡的primary ip garp_master_delay #在切换到master状态后,延迟进行gratuitous ARP请求 virtual_router_id 50 #VPID标记 priority 99 #优先级,高优先级竞选为master advert_int 1 #检查间隔,默认1秒 nopreempt #设置为不抢占 注:这个配置只能设置在backup主机上,而且这个主机优先级要比另外一台高 preempt_delay #抢占延时,默认5分钟 debug #debug级别 authentication { #设置认证 auth_type PASS #认证方式 auth_pass 111111 #认证密码 } virtual_ipaddress { #设置vip 192.168.202.200 } }
第四部分:虚拟服务器virtual_server定义块
虚拟服务器定义是keepalived框架最重要的项目了,是keepalived.conf必不可少的部分。 该部分是用来管理LVS的,是实现keepalive和LVS相结合的模块。ipvsadm命令可以实现的管理在这里都可以通过参数配置实现,注意:real_server是被包含在viyual_server模块中的,是子模块。
virtual_server 192.168.202.200 23 { //VIP地址,要和vrrp_instance模块中的virtual_ipaddress地址一致 delay_loop 6 #健康检查时间间隔 lb_algo rr #lvs调度算法rr|wrr|lc|wlc|lblc|sh|dh lb_kind DR #负载均衡转发规则NAT|DR|RUN persistence_timeout 5 #会话保持时间 protocol TCP #使用的协议 persistence_granularity <NETMASK> #lvs会话保持粒度 virtualhost <string> #检查的web服务器的虚拟主机(host:头) sorry_server<IPADDR> <port> #备用机,所有realserver失效后启用 real_server 192.168.200.5 23 { //RS的真实IP地址 weight 1 #默认为1,0为失效 inhibit_on_failure #在服务器健康检查失效时,将其设为0,而不是直接从ipvs中删除 notify_up <string> | <quoted-string> #在检测到server up后执行脚本 notify_down <string> | <quoted-string> #在检测到server down后执行脚本 TCP_CHECK { //常用 connect_timeout 3 #连接超时时间 nb_get_retry 3 #重连次数 delay_before_retry 3 #重连间隔时间 connect_port 23 健康检查的端口的端口 bindto <ip> } HTTP_GET | SSL_GET{ //不常用 url{ #检查url,可以指定多个 path / digest <string> #检查后的摘要信息 status_code 200 #检查的返回状态码 } connect_port <port> bindto <IPADD> connect_timeout 5 nb_get_retry 3 delay_before_retry 2 } SMTP_CHECK{ //不常用 host{ connect_ip <IP ADDRESS> connect_port <port> #默认检查25端口 bindto <IP ADDRESS> } connect_timeout 5 retry 3 delay_before_retry 2 helo_name <string> | <quoted-string> #smtp helo请求命令参数,可选 } MISC_CHECK{ //不常用 misc_path <string> | <quoted-string> #外部脚本路径 misc_timeout #脚本执行超时时间 misc_dynamic #如设置该项,则退出状态码会用来动态调整服务器的权重,返回0 正常,不修改;返回1, 检查失败,权重改为0;返回2-255,正常,权重设置为:返回状态码-2 } }
生产环境配置文件实例:
[root@LB2 ~]# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { [email protected] } notification_email_from [email protected] smtp_server 10.0.0.1 smtp_connect_timeout 30 router_id LVS_2 } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 55 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.220.110/24 } virtual_server 192.168.220.110 80 { delay_loop 6 lb_algo wrr lb_kind DR nat_mask 255.255.255.0 persistence_timeout 300 protocol TCP } real_server 192.168.220.129 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } real_server 192.168.220.138 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } } [root@LB2 ~]#
为keepalive指定日志文件
默认keepalive的日志文件是 /var/log/messages [root@LB2 ~]# tail -5 /var/log/messages Dec 7 22:40:10 LB2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE Dec 7 22:40:10 LB2 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)] Dec 7 22:40:10 LB2 Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'. Dec 7 22:40:10 LB2 Keepalived_healthcheckers: Configuration is using : 8425 Bytes Dec 7 22:40:10 LB2 Keepalived_healthcheckers: Using LinkWatch kernel netlink reflector... [root@LB2 ~]#
修改配置
[root@LB2 ~]# vim /etc/sysconfig/keepalived ...... #KEEPALIVED_OPTIONS="-D" //注释掉该行 KEEPALIVED_OPTIONS="-D -d -S 0" //添加改行 ...... [root@LB2 ~]# vim /etc/rsyslog.conf ...... local0.* /var/log/keepalived.log //添加改行 [root@LB2 ~]# /etc/init.d/rsyslog restart //重启日志服务 Shutting down system logger: [ OK ] Starting system logger: [ OK ] [root@LB2 ~]# /etc/init.d/keepalived restart //重启keepalive服务 Stopping keepalived: [ OK ] Starting keepalived: [ OK ] [root@LB2 ~]# tail -5 /var/log/keepalived.log Dec 8 01:02:06 LB2 Keepalived_vrrp: Virtual IP = 1 Dec 8 01:02:06 LB2 Keepalived_vrrp: 192.168.220.110/24 brd 192.168.220.110 dev eth0 scope global Dec 8 01:02:06 LB2 Keepalived_vrrp: Using LinkWatch kernel netlink reflector... Dec 8 01:02:06 LB2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE Dec 8 01:02:06 LB2 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)] [root@LB2 ~]#标签:LB2,--,keepalived,etc,vrrp,shell,使用,keeplive From: https://www.cnblogs.com/hzq0311/p/18338056