Nginx+Keeplived双机热备(主从模式)
参考资料：
http://www.cnblogs.com/kevingrace/p/6138185.html
双机高可用一般是通过虚拟IP(漂移IP)方法来实现的，基于Linux/Unix的IP别名技术。
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：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，同事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。
今天再次分享下Nginx+keeplived实现高可用负载均衡的主从模式的操作记录：
keeplived可以认为是VRRP协议在Linux上的实现，主要有三个模块，分别是core，check和vrrp。
core模块为keeplived的核心，负责主进程的启动、维护以及全局配置文件的加载和解析。
check负责健康检查，包括创建的各种检查方式。
vrrp模块是来实现VRRP协议的。
一、环境说明
操作系统：CentOS release 6.9 (Final) minimal
web1：172.16.12.223
web2：172.16.12.224
vip：svn：172.16.12.226
svn：172.16.12.225
二、环境安装
安装nginx和keeplived服务(web1和web2两台服务器上的安装完全一样)。
2.1、安装依赖
yum clean all yum -y update yum -y install gcc-c++ gd libxml2-devel libjpeg-devel libpng-devel net-snmp-devel wget telnet vim zip unzip yum -y install curl-devel libxslt-devel pcre-devel libjpeg libpng libcurl4-openssl-dev yum -y install libcurl-devel libcurl freetype-config freetype freetype-devel unixODBC libxslt yum -y install gcc automake autoconf libtool openssl-devel yum -y install perl-devel perl-ExtUtils-Embed yum -y install cmake ncurses-devel.x86_64 openldap-devel.x86_64 lrzsz openssh-clients gcc-g77 bison yum -y install libmcrypt libmcrypt-devel mhash mhash-devel bzip2 bzip2-devel yum -y install ntpdate rsync svn patch iptables iptables-services yum -y install libevent libevent-devel cyrus-sasl cyrus-sasl-devel yum -y install gd-devel libmemcached-devel memcached git libssl-devel libyaml-devel auto make yum -y groupinstall "Server Platform Development" "Development tools" yum -y groupinstall "Development tools" yum -y install gcc pcre-devel zlib-devel openssl-devel
2.2、Centos6系统安装完毕后，需要优化的地方
#关闭SELinux sed -i 's/SELINUX=enforcing/SELinux=disabled/' /etc/selinux/config grep SELINUX=disabled /etc/selinux/config setenforce 0 getenforce cat >> /etc/sysctl.conf << EOF # ##custom # net.ipv4.ip_forward = 0 net.ipv4.conf.default.rp_filter = 1 net.ipv4.conf.default.accept_source_route = 0 kernel.sysrq = 0 kernel.core_uses_pid = 1 net.ipv4.tcp_syncookies = 1 kernel.msgmnb = 65536 kernel.msgmax = 65536 net.ipv4.tcp_max_tw_buckets = 6000 net.ipv4.tcp_sack = 1 net.ipv4.tcp_window_scaling = 1 net.ipv4.tcp_rmem = 4096 87380 4194304 net.ipv4.tcp_wmem = 4096 16384 4194304 net.core.wmem_default = 8388608 net.core.rmem_default = 8388608 net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.core.netdev_max_backlog = 262144 net.core.somaxconn = 262144 net.ipv4.tcp_max_orphans = 3276800 net.ipv4.tcp_max_syn_backlog = 262144 net.ipv4.tcp_timestamps = 0 #net.ipv4.tcp_synack_retries = 1 net.ipv4.tcp_synack_retries = 2 #net.ipv4.tcp_syn_retries = 1 net.ipv4.tcp_syn_retries = 2 net.ipv4.tcp_tw_recycle = 1 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_mem = 94500000 915000000 927000000 #net.ipv4.tcp_fin_timeout = 1 net.ipv4.tcp_fin_timeout = 15 net.ipv4.tcp_keepalive_time = 30 net.ipv4.ip_local_port_range = 1024 65535 #net.ipv4.tcp_tw_len = 1 EOF #使其生效 sysctl -p cp /etc/security/limits.conf /etc/security/limits.conf.bak2017 cat >> /etc/security/limits.conf << EOF # ###custom # * soft nofile 20480 * hard nofile 65535 * soft nproc 20480 * hard nproc 65535 EOF
2.3、修改shell终端的超时时间
vi /etc/profile 增加如下一行即可（3600秒,默认不超时） cp /etc/profile /etc/profile.bak2017 cat >> /etc/profile << EOF export TMOUT=1800 EOF
2.4、下载软件包
（master和slave两台负载均衡机都要做） [root@web1 ~]# cd /usr/local/src/ [root@web1 src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz [root@web1 src]# wget http://www.keepalived.org/software/keepalived-1.3.2.tar.gz
2.5、安装nginx
（master和slave两台负载均衡机都要做） [root@web1 src]# tar -zxvf nginx-1.9.7.tar.gz [root@web1 nginx-1.9.7]# cd nginx-1.9.7 # 添加www用户，其中-M参数表示不添加用户家目录，-s参数表示指定shell类型 [root@web1 nginx-1.9.7]# useradd www -M -s /sbin/nologin [root@web1 nginx-1.9.7]# vim auto/cc/gcc #将这句注释掉 取消Debug编译模式 大概在179行 # debug # CFLAGS="$CFLAGS -g" [root@web1 nginx-1.9.7]# ./configure --prefix=/usr/local/nginx --user=www --group=www --with-http_ssl_module --with-http_flv_module --with-http_stub_status_module --with-http_gzip_static_module --with-pcre [root@web1 nginx-1.9.7]# make && make install
2.6、安装keeplived
（master和slave两台负载均衡机都要做） [root@web1 nginx-1.9.7]# cd /usr/local/src/ [root@web1 src]# tar -zvxf keepalived-1.3.2.tar.gz [root@web1 src]# cd keepalived-1.3.2 [root@web1 keepalived-1.3.2]# ./configure [root@web1 keepalived-1.3.2]# make && make install [root@web1 keepalived-1.3.2]# cp /usr/local/src/keepalived-1.3.2/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/ [root@web1 keepalived-1.3.2]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/ [root@web1 keepalived-1.3.2]# mkdir /etc/keepalived [root@web1 keepalived-1.3.2]# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/ [root@web1 keepalived-1.3.2]# cp /usr/local/sbin/keepalived /usr/sbin/ [root@web1 keepalived-1.3.2]# echo "/usr/local/nginx/sbin/nginx" >> /etc/rc.local [root@web1 keepalived-1.3.2]# echo "/etc/init.d/keepalived start" >> /etc/rc.local
三、配置服务
3.1、关闭selinux
先关闭SElinux、配置防火墙 （master和slave两台负载均衡机都要做） [root@web1 keepalived-1.3.2]# cd /root/ [root@web1 ~]#sed -i 's/SELINUX=enforcing/SELinux=disabled/' /etc/selinux/config [root@web1 ~]#grep SELINUX=disabled /etc/selinux/config [root@web1 ~]#setenforce 0
3.2、关闭防火墙
[root@web1 ~]# /etc/init.d/iptables stop
3.3、配置nginx
master-和slave两台服务器的nginx的配置完全一样,主要是配置/usr/local/nginx/conf/nginx.conf的http，当然也可以配置vhost虚拟主机目录，然后配置vhost下的比如LB.conf文件。
其中:
多域名指向是通过虚拟主机（配置http下面的server）实现;
同一域名的不同虚拟目录通过每个server下面的不同location实现;
到后端的服务器在vhost/LB.conf下面配置upstream,然后在server或location中通过proxy_pass引用。
要实现前面规划的接入方式，LB.conf的配置如下（添加proxy_cache_path和proxy_temp_path这两行，表示打开nginx的缓存功能）：
[root@web1 ~]# vim /usr/local/nginx/conf/nginx.conf user www; worker_processes 8; #error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error.log info; #pid logs/nginx.pid; events { worker_connections 65535; } http { include mime.types; default_type application/octet-stream; charset utf-8; ###### ### set access log format ####### log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; #access_log logs/access.log main; ####### ## http setting ####### sendfile on; #tcp_nopush on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 65; proxy_cache_path /var/www/cache levels=1:2 keys_zone=mycache:20m max_size=2048m inactive=60m; proxy_temp_path /var/www/cache/tmp; fastcgi_connect_timeout 3000; fastcgi_send_timeout 3000; fastcgi_read_timeout 3000; fastcgi_buffer_size 256k; fastcgi_buffers 8 256k; fastcgi_busy_buffers_size 256k; fastcgi_temp_file_write_size 256k; fastcgi_intercept_errors on; #keepalive_timeout 0; #keepalive_timeout 65; # client_header_timeout 600s; client_body_timeout 600s; # client_max_body_size 50m; client_max_body_size 100m; #允许客户端请求的最大单个文件字节数 client_body_buffer_size 256k; #缓冲区代理缓冲请求的最大字节数，可以理解为先保存到本地再传给用户 #gzip on; gzip_min_length 1k; gzip_buffers 4 16k; gzip_http_version 1.1; gzip_comp_level 9; gzip_types text/plain application/x-javascript text/css application/xml text/javascript application/x-httpd-php; gzip_vary on; ## includes vhosts include vhosts/*.conf; } # 创建相应的目录 [root@web1 ~]# mkdir -p /usr/local/nginx/conf/vhosts [root@web1 ~]# mkdir -p /var/www/cache [root@web1 ~]# ulimit 65535 [root@web2 ~]# vim /usr/local/nginx/conf/vhosts/LB.conf upstream LB-WWW { ip_hash; server 172.16.12.223:80 max_fails=3 fail_timeout=30s; #max_fails = 3 为允许失败的次数，默认值为1 server 172.16.12.224:80 max_fails=3 fail_timeout=30s; #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 server 172.16.12.225:80 max_fails=3 fail_timeout=30s; } upstream LB-OA { ip_hash; server 172.16.12.223:8080 max_fails=3 fail_timeout=30s; server 172.16.12.224:8080 max_fails=3 fail_timeout=30s; } server { listen 80; server_name localhost; access_log /usr/local/nginx/logs/dev-access.log main; error_log /usr/local/nginx/logs/dev-error.log; location /svn { proxy_pass http://172.16.12.226/svn/; proxy_redirect off ; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header REMOTE-HOST $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_connect_timeout 300; #跟后端服务器连接超时时间，发起握手等候响应时间 proxy_send_timeout 300; #后端服务器回传时间，就是在规定时间内后端服务器必须传完所有数据 proxy_read_timeout 600; #连接成功后等待后端服务器的响应时间，已经进入后端的排队之中等候处理 proxy_buffer_size 256k; #代理请求缓冲区,会保存用户的头信息以供nginx进行处理 proxy_buffers 4 256k; #同上，告诉nginx保存单个用几个buffer最大用多少空间 proxy_busy_buffers_size 256k; #如果系统很忙时候可以申请最大的proxy_buffers proxy_temp_file_write_size 256k; #proxy缓存临时文件的大小 proxy_next_upstream error timeout invalid_header http_500 http_503 http_404; proxy_max_temp_file_size 128m; proxy_cache mycache; proxy_cache_valid 200 302 60m; proxy_cache_valid 404 1m; } location /submin { proxy_pass http://172.16.12.226/submin/; proxy_redirect off ; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header REMOTE-HOST $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_connect_timeout 300; proxy_send_timeout 300; proxy_read_timeout 600; proxy_buffer_size 256k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k; proxy_temp_file_write_size 256k; proxy_next_upstream error timeout invalid_header http_500 http_503 http_404; proxy_max_temp_file_size 128m; proxy_cache mycache; proxy_cache_valid 200 302 60m; proxy_cache_valid 404 1m; } } server { listen 80; server_name localhost; access_log /usr/local/nginx/logs/www-access.log main; error_log /usr/local/nginx/logs/www-error.log; location / { proxy_pass http://LB-WWW; proxy_redirect off ; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header REMOTE-HOST $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_connect_timeout 300; proxy_send_timeout 300; proxy_read_timeout 600; proxy_buffer_size 256k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k; proxy_temp_file_write_size 256k; proxy_next_upstream error timeout invalid_header http_500 http_503 http_404; proxy_max_temp_file_size 128m; proxy_cache mycache; proxy_cache_valid 200 302 60m; proxy_cache_valid 404 1m; } } server { listen 80; server_name localhost; access_log /usr/local/nginx/logs/oa-access.log main; error_log /usr/local/nginx/logs/oa-error.log; location / { proxy_pass http://LB-OA; proxy_redirect off ; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header REMOTE-HOST $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_connect_timeout 300; proxy_send_timeout 300; proxy_read_timeout 600; proxy_buffer_size 256k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k; proxy_temp_file_write_size 256k; proxy_next_upstream error timeout invalid_header http_500 http_503 http_404; proxy_max_temp_file_size 128m; proxy_cache mycache; proxy_cache_valid 200 302 60m; proxy_cache_valid 404 1m; } }
3.4、验证准备
3.4.1、在svn服务器上执行
cat >/usr/local/nginx/conf/vhosts/svn.conf <<EOF server { listen 80; server_name svn 172.16.12.225; access_log /usr/local/nginx/logs/svn-access.log main; error_log /usr/local/nginx/logs/svn-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } EOF [root@svn ~]# cat /usr/local/nginx/conf/vhosts/svn.conf server { listen 80; server_name svn 172.16.12.225; access_log /usr/local/nginx/logs/svn-access.log main; error_log /usr/local/nginx/logs/svn-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } [root@svn ~]# [root@svn ~]# mkdir -p /var/www/html [root@svn ~]# mkdir -p /var/www/html/submin [root@svn ~]# mkdir -p /var/www/html/svn [root@svn ~]# cat /var/www/html/svn/index.html this is the page of svn/172.16.12.225 [root@svn ~]# cat /var/www/html/submin/index.html this is the page of submin/172.16.12.225 [root@svn ~]# chown -R www.www /var/www/html/ [root@svn ~]# chmod -R 755 /var/www/html/ [root@svn ~]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 172.16.12.223 web1 172.16.12.224 web2 172.16.12.225 svn [root@svn ~]# tail -4 /etc/rc.local touch /var/lock/subsys/local /etc/init.d/iptables stop /usr/local/nginx/sbin/nginx /etc/init.d/keepalived start # 启动nginx [root@svn ~]# /usr/local/nginx/sbin/nginx # 访问网址 [root@svn local]# curl http://172.16.12.225/submin/ this is the page of submin/172.16.12.225 [root@svn local]# curl http://172.16.12.225/svn/ this is the page of svn/172.16.12.225
3.4.1、在web1上执行
[root@web1 ~]# curl http://172.16.12.225/submin/ this is the page of submin/172.16.12.225 [root@web1 ~]# curl http://172.16.12.225/svn/ this is the page of svn/172.16.12.225 cat >/usr/local/nginx/conf/vhosts/web.conf <<EOF server { listen 80; server_name web 172.16.12.223; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } EOF [root@web1 ~]# cat /usr/local/nginx/conf/vhosts/web.conf server { listen 80; server_name web 172.16.12.223; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } [root@web1 ~]# mkdir -p /var/www/html [root@web1 ~]# mkdir -p /var/www/html/web [root@web1 ~]# cat /var/www/html/web/index.html this is the page of web/172.16.12.223 [root@web1 ~]# chown -R www.www /var/www/html/ [root@web1 ~]# chmod -R 755 /var/www/html/ [root@web1 ~]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 172.16.12.223 web1 172.16.12.224 web2 172.16.12.225 svn [root@web1 ~]# tail -4 /etc/rc.local touch /var/lock/subsys/local /etc/init.d/iptables stop /usr/local/nginx/sbin/nginx /etc/init.d/keepalived start [root@web1 ~]# /usr/local/nginx/sbin/nginx [root@web1 ~]# curl http://172.16.12.223/web/ this is the page of web/172.16.12.223
2.4.2、在web2上执行
[root@web2 ~]# curl http://172.16.12.225/submin/ this is the page of submin/172.16.12.225 [root@web2 ~]# curl http://172.16.12.225/svn/ this is the page of svn/172.16.12.225 cat >/usr/local/nginx/conf/vhosts/web.conf <<EOF server { listen 80; server_name web 172.16.12.224; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } EOF [root@web2 ~]# cat /usr/local/nginx/conf/vhosts/web.conf server { listen 80; server_name web 172.16.12.224; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } [root@web2 ~]# [root@web2 ~]# mkdir -p /var/www/html [root@web2 ~]# mkdir -p /var/www/html/web [root@web2 ~]# cat /var/www/html/web/index.html this is the page of web/172.16.12.224 [root@web2 ~]# cat /var/www/html/web/index.html this is the page of web/172.16.12.224 [root@web2 ~]# chown -R www.www /var/www/html/ [root@web2 ~]# chmod -R 755 /var/www/html/ [root@web2 ~]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 172.16.12.223 web1 172.16.12.224 web2 172.16.12.225 svn [root@web2 ~]# tail -4 /etc/rc.local touch /var/lock/subsys/local /etc/init.d/iptables stop /usr/local/nginx/sbin/nginx /etc/init.d/keepalived start # 启动nginx [root@web2 ~]# /usr/local/nginx/sbin/nginx # 访问网址 [root@web2 local]# curl http://172.16.12.224/web/ this is the page of web/172.16.12.224
2.4.3、浏览器测试
四、keeplived配置
4.1、web1上的操作
[root@web1 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak [root@web1 ~]# vim /etc/keepalived/keepalived.conf ! Configuration File for keepalived #全局定义 global_defs { # notification_email { #指定keepalived在发生事件时(比如切换)发送通知邮件的邮箱 # ops@wangshibo.cn #设置报警邮件地址，可以设置多个，每行一个。 需开启本机的sendmail服务 # tech@wangshibo.cn # } # # notification_email_from ops@wangshibo.cn #keepalived在发生诸如切换操作时需要发送email通知地址 # smtp_server 127.0.0.1 #指定发送email的smtp服务器 # smtp_connect_timeout 30 #设置连接smtp server的超时时间 router_id master-node #运行keepalived的机器的一个标识，通常可设为hostname。故障发生时，发邮件时显示在邮件主题中的信息。 } vrrp_script chk_http_port { #检测nginx服务是否在运行。有很多方式，比如进程，用脚本检测等等 script "/opt/chk_nginx.sh" #这里通过脚本监测 interval 2 #脚本执行间隔，每2s检测一次 weight -5 #脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5 fall 2 #检测连续2次失败才算确定是真失败。会用weight减少优先级（1-255之间） rise 1 #检测1次成功就算成功。但不修改优先级 } vrrp_instance VI_1 { #keepalived在同一virtual_router_id中priority（0-255）最大的会成为master，也就是接管VIP，当priority最大的主机发生故障后次priority将会接管 state MASTER #指定keepalived的角色，MASTER表示此主机是主服务器，BACKUP表示此主机是备用服务器。注意这里的state指定instance(Initial)的初始状态，就是说在配置好后，这台服务器的初始状态就是这里指定的，但这里指定的不算，还是得要通过竞选通过优先级来确定。如果这里设置为MASTER，但如若他的优先级不及另外一台，那么这台在发送通告时，会发送自己的优先级，另外一台发现优先级不如自己的高，那么他会就回抢占为MASTER interface eth1 #指定HA监测网络的接口。实例绑定的网卡，因为在配置虚拟IP的时候必须是在已有的网卡上添加的 # mcast_src_ip 103.110.98.14 # 发送多播数据包时的源IP地址，这里注意了，这里实际上就是在哪个地址上发送VRRP通告，这个非常重要，一定要选择稳定的网卡端口来发送，这里相当于heartbeat的心跳端口，如果没有设置那么就用默认的绑定的网卡的IP，也就是interface指定的IP地址 virtual_router_id 226 #虚拟路由标识，这个标识是一个数字，同一个vrrp实例使用唯一的标识。即同一vrrp_instance下，MASTER和BACKUP必须是一致的 priority 101 #定义优先级，数字越大，优先级越高，在同一个vrrp_instance下，MASTER的优先级必须大于BACKUP的优先级 advert_int 1 #设定MASTER与BACKUP负载均衡器之间同步检查的时间间隔，单位是秒 authentication { #设置验证类型和密码。主从必须一样 auth_type PASS #设置vrrp验证类型，主要有PASS和AH两种 auth_pass 1111 #设置vrrp验证密码，在同一个vrrp_instance下，MASTER与BACKUP必须使用相同的密码才能正常通信 } virtual_ipaddress { #VRRP HA 虚拟地址 如果有多个VIP，继续换行填写 172.16.12.226 } track_script { #执行监控的服务。注意这个设置不能紧挨着写在vrrp_script配置块的后面（实验中碰过的坑），否则nginx监控失效！！ chk_http_port #引用VRRP脚本，即在 vrrp_script 部分指定的名字。定期运行它们来改变优先级，并最终引发主备切换。 } }
4.2、web2上的操作
[root@web2 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak [root@web2 ~]# vim /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { # notification_email { # ops@wangshibo.cn # tech@wangshibo.cn # } # # notification_email_from ops@wangshibo.cn # smtp_server 127.0.0.1 # smtp_connect_timeout 30 router_id slave-node } vrrp_script chk_http_port { script "/opt/chk_nginx.sh" interval 2 weight -5 fall 2 rise 1 } vrrp_instance VI_1 { state BACKUP interface eth1 # mcast_src_ip 103.110.98.24 virtual_router_id 226 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 172.16.12.226 } track_script { chk_http_port } }
4.3、监控说明
让keepalived监控NginX的状态：
1）经过前面的配置，如果master主服务器的keepalived停止服务，slave从服务器会自动接管VIP对外服务；
一旦主服务器的keepalived恢复，会重新接管VIP。 但这并不是我们需要的，我们需要的是当NginX停止服务的时候能够自动切换。
2）keepalived支持配置监控脚本，我们可以通过脚本监控NginX的状态，如果状态不正常则进行一系列的操作，最终仍不能恢复NginX则杀掉keepalived，使得从服务器能够接管服务。
如何监控NginX的状态
最简单的做法是监控NginX进程，更靠谱的做法是检查NginX端口，最靠谱的做法是检查多个url能否获取到页面。
注意：这里要提示一下keepalived.conf中vrrp_script配置区的script一般有2种写法：
1）通过脚本执行的返回结果，改变优先级，keepalived继续发送通告消息，backup比较优先级再决定。这是直接监控Nginx进程的方式。
2）脚本里面检测到异常，直接关闭keepalived进程，backup机器接收不到advertisement会抢占IP。这是检查NginX端口的方式。
上文script配置部分，"killall -0 nginx"属于第1种情况，"/opt/chk_nginx.sh" 属于第2种情况。个人更倾向于通过shell脚本判断，但有异常时exit 1，正常退出exit 0，然后keepalived根据动态调整的 vrrp_instance 优先级选举决定是否抢占VIP：
如果脚本执行结果为0，并且weight配置的值大于0，则优先级相应的增加
如果脚本执行结果非0，并且weight配置的值小于0，则优先级相应的减少
其他情况，原本配置的优先级不变，即配置文件中priority对应的值。
提示：
优先级不会不断的提高或者降低
可以编写多个检测脚本并为每个检测脚本设置不同的weight（在配置中列出就行）
不管提高优先级还是降低优先级，最终优先级的范围是在[1,254]，不会出现优先级小于等于0或者优先级大于等于255的情况
在MASTER节点的 vrrp_instance 中 配置 nopreempt ，当它异常恢复后，即使它 prio 更高也不会抢占，这样可以避免正常情况下做无谓的切换
以上可以做到利用脚本检测业务进程的状态，并动态调整优先级从而实现主备切换。
另外：在默认的keepalive.conf里面还有 virtual_server,real_server 这样的配置，我们这用不到，它是为lvs准备的。
如何尝试恢复服务
由于keepalived只检测本机和他机keepalived是否正常并实现VIP的漂移，而如果本机nginx出现故障不会则不会漂移VIP。
所以编写脚本来判断本机nginx是否正常，如果发现NginX不正常，重启之。等待3秒再次校验，仍然失败则不再尝试，关闭keepalived，其他主机此时会接管VIP；
根据上述策略很容易写出监控脚本。此脚本必须在keepalived服务运行的前提下才有效！如果在keepalived服务先关闭的情况下，那么nginx服务关闭后就不能实现自启动了。
该脚本检测ngnix的运行状态，并在nginx进程不存在时尝试重新启动ngnix，如果启动失败则停止keepalived，准备让其它机器接管。
4.4、监控脚本
监控脚本如下（master和slave都要有这个监控脚本）： [root@web1 ~]# cat /opt/chk_nginx.sh #!/bin/bash counter=$(ps -C nginx --no-heading|wc -l) if [ "${counter}" = "0" ]; then /usr/local/nginx/sbin/nginx sleep 2 counter=$(ps -C nginx --no-heading|wc -l) if [ "${counter}" = "0" ]; then /etc/init.d/keepalived stop fi fi [root@web1 ~]# [root@web1 ~]# chmod 755 /opt/chk_nginx.sh [root@web1 ~]# sh /opt/chk_nginx.sh [root@web2 ~]# cat /opt/chk_nginx.sh #!/bin/bash counter=$(ps -C nginx --no-heading|wc -l) if [ "${counter}" = "0" ]; then /usr/local/nginx/sbin/nginx sleep 2 counter=$(ps -C nginx --no-heading|wc -l) if [ "${counter}" = "0" ]; then /etc/init.d/keepalived stop fi fi [root@web2 ~]# [root@web2 ~]# chmod 755 /opt/chk_nginx.sh [root@web2 ~]# sh /opt/chk_nginx.sh
4.5、需要考虑的问题
此架构需考虑的问题
1）master没挂，则master占有vip且nginx运行在master上
2）master挂了，则slave抢占vip且在slave上运行nginx服务
3）如果master上的nginx服务挂了，则nginx会自动重启，重启失败后会自动关闭keepalived，这样vip资源也会转移到slave上。
4）检测后端服务器的健康状态
5）master和slave两边都开启nginx服务，无论master还是slave，当其中的一个keepalived服务停止后，vip都会漂移到keepalived服务还在的节点上；
如果要想使nginx服务挂了，vip也漂移到另一个节点，则必须用脚本或者在配置文件里面用shell命令来控制。（nginx服务宕停后会自动启动，启动失败后会强制关闭keepalived，从而致使vip资源漂移到另一台机器上）
五、最后验证
最后验证（将配置的后端应用域名都解析到VIP地址上）：关闭主服务器上的keepalived或nginx，vip都会自动飘到从服务器上。
验证keepalived服务故障情况：
1）先后在master、slave服务器上启动nginx和keepalived，保证这两个服务都正常开启:
[root@web2 ~]# /usr/local/nginx/sbin/nginx -s stop nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored [root@web2 ~]# /etc/init.d/keepalived stop Stopping keepalived: [FAILED] [root@web2 ~]# [root@web1 ~]# /usr/local/nginx/sbin/nginx -s stop nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored [root@web1 ~]# /etc/init.d/keepalived stop Stopping keepalived: [FAILED] [root@web1 ~]# [root@web1 ~]# /usr/local/nginx/sbin/nginx nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored [root@web1 ~]# /etc/init.d/keepalived start Starting keepalived: [ OK ]
2）在主服务器上查看是否已经绑定了虚拟IP：
[root@web1 ~]# ip add 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:ca:99:56 brd ff:ff:ff:ff:ff:ff inet 10.0.2.223/24 brd 10.0.2.255 scope global eth0 inet 172.16.12.226/32 scope global eth0 inet6 fe80::a00:27ff:feca:9956/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:b3:a9:36 brd ff:ff:ff:ff:ff:ff inet 172.16.12.223/24 brd 172.16.12.255 scope global eth1 inet6 fe80::a00:27ff:feb3:a936/64 scope link valid_lft forever preferred_lft forever [root@web2 ~]# /usr/local/nginx/sbin/nginx nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored nginx: [warn] conflicting server name "localhost" on 0.0.0.0:80, ignored [root@web2 ~]# /etc/init.d/keepalived start Starting keepalived: [ OK ] [root@web2 ~]# ip add 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:9a:0b:97 brd ff:ff:ff:ff:ff:ff inet 10.0.2.224/24 brd 10.0.2.255 scope global eth0 inet6 fe80::a00:27ff:fe9a:b97/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:63:26:1a brd ff:ff:ff:ff:ff:ff inet 172.16.12.224/24 brd 172.16.12.255 scope global eth1 inet6 fe80::a00:27ff:fe63:261a/64 scope link valid_lft forever preferred_lft forever [root@web2 ~]#
5.1、修改网站配置
[root@web1 ~]# cat /usr/local/nginx/conf/vhosts/web.conf server { listen 80; server_name localhost 172.16.12.223 172.16.12.226; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } [root@web1 ~]# [root@web2 ~]# cat /usr/local/nginx/conf/vhosts/web.conf server { listen 80; server_name localhost 172.16.12.224 172.16.12.226; access_log /usr/local/nginx/logs/web-access.log main; error_log /usr/local/nginx/logs/web-error.log; location / { root /var/www/html; index index.html index.php index.htm; } } [root@web2 ~]#
5.2、访问验证
5.3、停止主服务器的keeplived服务
[root@web1 ~]# /etc/init.d/keepalived stop Stopping keepalived: [ OK ] [root@web1 ~]# [root@web1 ~]# tail -f /var/log/messages Dec 14 13:32:12 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:12 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:12 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:12 web1 Keepalived_healthcheckers[7958]: Netlink reflector reports IP 172.16.12.226 added Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 172.16.12.226 Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:32:17 web1 Keepalived_vrrp[7959]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:43:51 web1 Keepalived[7956]: Stopping Dec 14 13:43:51 web1 Keepalived_vrrp[7959]: VRRP_Instance(VI_1) sent 0 priority Dec 14 13:43:51 web1 Keepalived_vrrp[7959]: VRRP_Instance(VI_1) removing protocol VIPs. Dec 14 13:43:51 web1 Keepalived_healthcheckers[7958]: Netlink reflector reports IP 172.16.12.226 removed Dec 14 13:43:51 web1 Keepalived_healthcheckers[7958]: Stopped Dec 14 13:43:52 web1 Keepalived_vrrp[7959]: Stopped Dec 14 13:43:52 web1 Keepalived[7956]: Stopped Keepalived v1.3.2 (12/14,2017) [root@web1 ~]# ip add 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:ca:99:56 brd ff:ff:ff:ff:ff:ff inet 10.0.2.223/24 brd 10.0.2.255 scope global eth0 inet6 fe80::a00:27ff:feca:9956/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:b3:a9:36 brd ff:ff:ff:ff:ff:ff inet 172.16.12.223/24 brd 172.16.12.255 scope global eth1 inet6 fe80::a00:27ff:feb3:a936/64 scope link valid_lft forever preferred_lft forever [root@web1 ~]#
5.4、在web2查看切换情况
[root@web2 ~]# ip add 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:9a:0b:97 brd ff:ff:ff:ff:ff:ff inet 10.0.2.224/24 brd 10.0.2.255 scope global eth0 inet 172.16.12.226/32 scope global eth0 inet6 fe80::a00:27ff:fe9a:b97/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:63:26:1a brd ff:ff:ff:ff:ff:ff inet 172.16.12.224/24 brd 172.16.12.255 scope global eth1 inet6 fe80::a00:27ff:fe63:261a/64 scope link valid_lft forever preferred_lft forever [root@web2 ~]# [root@web2 ~]# tail -f /var/log/messages Dec 14 13:47:33 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:33 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:33 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:33 web2 Keepalived_healthcheckers[8186]: Netlink reflector reports IP 172.16.12.226 added Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 172.16.12.226 Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226 Dec 14 13:47:38 web2 Keepalived_vrrp[8187]: Sending gratuitous ARP on eth0 for 172.16.12.226
5.5、访问网页验证
切换前的网页：
切换后的网页：
说明已经切换完毕。