Nginx+keepalived双机热备（主主模式）
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nginx+keepalived实现高可用负载均衡的主主模式
由于网站的访问需求不断加大，负载越来越高。现需要在web前端放置nginx负载均衡,同时结合keepalived对前端nginx实现HA高可用。
1、nginx进程基于Master+Slave(worker模式)多进程模型，自身具有非常稳定的子进程管理功能。在Master进程分配模式下，Master进程永远不进行业务处理，只是进行任务分发，从而达到Master进程的存活高可靠性，Slave(worker)进程所有的业务信号都由主进程发出，Slave(worker)进程所有的超时任务都会被Master中止，属于非阻塞式任务模型。
2、Keepalived是Linux下面实现VRRP备份路由的高可靠性运行件。基于Keepalived设计的服务模式能够真正做到主服务器和备份服务器故障时IP瞬间无缝交接。二者结合，可以构架出比较稳定的软件LB方案。
双机高可用方法目前分为两种：
1）双机主从模式：即前端使用两台服务器，一台主服务器和一台热备服务器，正常情况下，主服务器绑定一个公网虚拟IP，提供负载均衡服务，热备服务器处于空闲状态；当主服务器发生故障时，热备服务器接管主服务器的公网虚拟IP，提供负载均衡服务；但是热备服务器在主机器不出现故障的时候，永远处于浪费状态，对于服务器不多的网站，该方案不经济实惠。
2）双机主主模式：这种模式的效果很强大，即前端使用两台负载均衡服务器，互为主备，且都处于活动状态（这样达到不浪费服务器），同时各自绑定一个公网虚拟IP，提供负载均衡服务；当其中一台发生故障时，另一台接管发生故障服务器的公网虚拟IP（这时由非故障机器一台负担所有的请求）。这种方案，经济实惠，非常适合于当前架构环境。
一、环境介绍：
操作系统：
[[email protected] ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)
服务器对应关系：
KA1：192.168.5.129 centos-1
KA2：192.168.5.128 centos-4
Vip1：192.168.5.200 129master/128backup
VIP2：192.168.5.210 128master/129backup
Web1：192.168.5.131 centos-2
Web2：192.168.5.132 centos-3
二、环境安装：
安装依赖：
（在KA1和KA2机器上执行以下步骤）
[[email protected]centos-4 ~]# yum -y install gcc pcre-devel zlib-devel openssl-devel
[[email protected]~]# cd /usr/local/src/
[[email protected] src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz
安装nginx
[[email protected] src]# tar -zvxfnginx-1.9.7.tar.gz
[[email protected] src]# cd nginx-1.9.7
[[email protected] nginx-1.9.7]#./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre
[[email protected] nginx-1.9.7]# make &&make install
[[email protected] ~]# yum install -ykeepalived
(在web1服务器和web2服务器上安装nginx)
[[email protected]~]# yum -y install gcc pcre-devel zlib-devel openssl-devel
[[email protected]~]# cd /usr/local/src/
[[email protected] src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz
安装nginx
[[email protected] src]# tar -zvxfnginx-1.9.7.tar.gz
[[email protected] src]# cd nginx-1.9.7
[[email protected] nginx-1.9.7]# ./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre
[[email protected] nginx-1.9.7]# make &&make install
三、配置服务：
（所以服务器上配置）
[[email protected] ~]# cat/etc/sysconfig/selinux
SELINUX=disabled
[[email protected] ~]# getenforce
Disabled
[[email protected] ~]# service iptables stop
1、配置keepalived：
（KA1上操作）
[[email protected] ~]#cat /etc/keepalived/keepalived.conf ! Configuration Filefor keepalived global_defs { notification_email { [email protected] #[email protected] #[email protected] } router_id LVS_DEVEL } vrrp_scriptchk_http_port { script "/opt/check_nginx.sh" interval 2 weight -5 fall 2 rise 1 } vrrp_instance VI_1{ state MASTER interface eth0 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.5.200 } } vrrp_instance VI_2{ state BACKUP interface eth0 virtual_router_id 50 priority 90 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.5.210 } track_script { chk_http_port } }
（KA2上操作）
[[email protected] ~]#cat /etc/keepalived/keepalived.conf ! Configuration Filefor keepalived global_defs { notification_email { [email protected] #[email protected] #[email protected] } router_id LVS_DEVEL } vrrp_scriptchk_http_port { script "/opt/check_nginx.sh" interval 2 weight -5 fall 2 rise 1 } vrrp_instance VI_1{ state BACKUP interface eth0 virtual_router_id 51 priority 90 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.5.200 } } vrrp_instance VI_2{ state MASTER interface eth0 virtual_router_id 50 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.5.210 } track_script { chk_http_port } }
编写一个监控nginx的脚本：
需要注意的是，要判断本机nginx是否正常，如果发现nginx不正常，重启之后，等待三秒在校验，任然失败则不尝试，关闭keepalived，发送邮件，其他主机此时接管VIP；
[[email protected]~]# cat /opt/check_nginx.sh #!/bin/bash check=$(ps-C nginx --no-heading|wc -l) IP=`ipadd | grep eth0 | awk ‘NR==2{print $2}‘| awk -F ‘/‘ ‘{print $1}‘` if ["${check}" = "0" ]; then /usr/local/nginx/sbin/nginx sleep 2 counter=$(ps -C nginx --no-heading|wc -l) if [ "${check}" = "0"]; then /etc/init.d/keepalived stop echo "check $IP nginx is down"| mail -s "check keepalived nginx" *********@qq.com fi fi
(KA1一样的监控脚本)
2、在两台前端服务器上启动keepalived服务，对于192.168.5.200的vip centos-1是master/192.168.5.210的vip centos-1是backup。
[[email protected] ~]#service keepalived start
[[email protected] ~]# service keepalived start
查看日志文件：
[[email protected] ~]# cat /var/log/messages
Oct 19 22:00:22 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210
Oct 19 22:00:22 centos-1 Keepalived_healthcheckers[46183]: Netlinkreflector reports IP 192.168.5.210 added
Oct 19 22:00:24 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_1)Sending gratuitous ARPs on eth0 for 192.168.5.200
Oct 19 22:00:27 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210
（因为KA1先启动keepalived服务所以两个vip都会在KA1上，但第二台keepaliver服务起来后vip2就会被KA2抢占回来。）
[[email protected] ~]# cat /var/log/messages
Oct 19 22:01:38 centos-4 Keepalived_healthcheckers[15009]: Netlinkreflector reports IP 192.168.5.210 added
Oct 19 22:01:38 centos-4 avahi-daemon[1513]: Registering new addressrecord for 192.168.5.210 on eth0.IPv4.
Oct 19 22:01:38 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210
Oct 19 22:01:43 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210
查看ip addr：
[[email protected] keepalived]# ip add
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_faststate UP qlen 1000
link/ether00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff
inet 192.168.5.129/24 brd192.168.5.255 scope global eth0
inet 192.168.5.200/32scope global eth0
[[email protected] keepalived]#ip addr
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdiscpfifo_fast state UP qlen 1000
link/ether00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff
inet 192.168.5.128/24 brd192.168.5.255 scope global eth0
inet 192.168.5.210/32 scope global eth0
3、配置nginx的反向代理
（在web1和web2服务器上配置两个web服务（可以http或者nginx）用来测试使用，这里就不一一演示了。）
[[email protected] ~]# curl localhost
2
[[email protected] ~]# curl localhost
3
（在两台前端服务器上配置）
[[email protected] ~]# vim/usr/local/nginx/conf/nginx.conf …… …… …… upstreambackend { ip_hash; server 192.168.5.131:80 max_fails=2fail_timeout=30s; server 192.168.5.132:80 max_fails=2fail_timeout=30s; #ip_hash: 每个请求按访问ip的hash结果分配，这样每个访客固定访问一个后端服务器，可以解决session的问题。 #max_fails=2 为允许失败的次数，默认值为1 #fail_timeout=30s 当max_fails次失败后，暂停将请求分发到该后端服务器的时间 } proxy_temp_path /usr/local/nginx/cache/tmp 1 2; proxy_cache_path /usr/local/nginx/cache levels=1:2 keys_zone=cache1:100m inactive=1dmax_size=10g; …… …… …… server { listen 80; server_name localhost; #charset koi8-r; #access_log logs/host.access.log main; location / { proxy_pass http://backend; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_cache cache1; add_header X-Cache$upstream_cache_status; proxy_cache_key $host$uri$is_args$args; proxy_cache_valid 200 304 10m; expires 30d; # root /web; index index.php index.html index.htm; }
[[email protected] ~]# vim/usr/local/nginx/conf/nginx.conf …… …… …… upstreambackend { ip_hash; server 192.168.5.131:80 max_fails=2fail_timeout=30s; server 192.168.5.132:80 max_fails=2fail_timeout=30s; } proxy_temp_path /usr/local/nginx/cache/tmp 1 2; proxy_cache_path /usr/local/nginx/cache levels=1:2 keys_zone=cache1:100m inactive=1dmax_size=10g; …… …… …… server { listen 80; server_name localhost; #charset koi8-r; #access_log logs/host.access.log main; location / { proxy_pass http://backend; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_cache cache1; add_header X-Cache$upstream_cache_status; proxy_cache_key $host$uri$is_args$args; proxy_cache_valid 200 304 10m; expires 30d; # root /web; index index.php index.html index.htm; }
（两台KA1和KA2服务器重启nginx、keepalived服务）
[[email protected]~]# /usr/local/nginx/sbin/nginx -t
nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful ###检查配置文件没问题后再执行重启nginx。
[[email protected]~]# /usr/local/nginx/sbin/nginx -s reload
[[email protected]~]# /usr/local/nginx/sbin/nginx -t
nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful
[[email protected]~]# /usr/local/nginx/sbin/nginx -s reload
[[email protected]~]# service keepalived restart
停止keepalived： [确定]
正在启动keepalived： [确定]
[[email protected]~]# service keepalived restart
停止keepalived： [确定]
正在启动keepalived： [确定]
四、测试：
验证方法（保证从负载均衡器本机到后端真实服务器之间能正常通信）：
（1）、先测试完成后的效果访问vip1、vip2
[[email protected] ~]# curl 192.168.5.200
10.2
[[email protected] ~]# curl 192.168.5.210
10.3
（注意在KA1、KA2上做了缓存）
（2）、把KA1keepalived stop掉（模拟KA1主机的keepalived故障）
[[email protected] ~]# service keepalived stop
停止 keepalived：
[[email protected] ~]# ip addr
2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000
link/ether 00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff
inet 192.168.5.129/24 brd 192.168.5.255 scope global eth0
inet6 fe80::20c:29ff:fe0d:f35d/64 scope link
valid_lft forever preferred_lft forever
（KA1主机上查看ip addr已经没有vip了。）
在KA2主机上查看日志文件：
[[email protected] ~]# cat /var/log/messages
Oct 19 23:20:46 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200
Oct 19 23:20:46 centos-4avahi-daemon[1513]: Registering new address record for 192.168.5.200 oneth0.IPv4.
Oct 19 23:20:46 centos-4 Keepalived_healthcheckers[15411]:Netlink reflector reports IP 192.168.5.200 added
Oct 19 23:20:51 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200
（日志文件显示已经把vip：192.168.5.200接管了）
查看KA2主机的ip addr
[[email protected] ~]# ip addr
2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000
link/ether 00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff
inet 192.168.5.128/24 brd 192.168.5.255 scope global eth0
inet 192.168.5.210/32 scope global eth0
inet 192.168.5.200/32 scope global eth0
（可以看到已经有两个vip）
检查nginx服务是否被KA2接管且不中断
[[email protected] ~]# curl 192.168.5.210
10.3
[[email protected] ~]# curl 192.168.5.200
10.2
（可以看到服务还是进行的而且缓存还在。）
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