Nginx+keepalived双机热备（主从模式）

Posted 2020-10-12 crazyYong

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负载均衡技术对于一个网站尤其是大型网站的web服务器集群来说是至关重要的！做好负载均衡架构，可以实现故障转移和高可用环境，避免单点故障，保证网站健康持续运行。
关于负载均衡介绍，可以参考：linux负载均衡总结性说明（四层负载/七层负载）

由于业务扩展，网站的访问量不断加大，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)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。

Heartbeat、Corosync、Keepalived这三个集群组件我们到底选哪个好呢？
首先要说明的是，Heartbeat、Corosync是属于同一类型，Keepalived与Heartbeat、Corosync，根本不是同一类型的。
Keepalived使用的vrrp协议方式，虚拟路由冗余协议 (Virtual Router Redundancy Protocol，简称VRRP)；
Heartbeat或Corosync是基于主机或网络服务的高可用方式；
简单的说就是，Keepalived的目的是模拟路由器的高可用，Heartbeat或Corosync的目的是实现Service的高可用。
所以一般Keepalived是实现前端高可用，常用的前端高可用的组合有，就是我们常见的LVS+Keepalived、Nginx+Keepalived、HAproxy+Keepalived。而Heartbeat或Corosync是实现服务的高可用，常见的组合有Heartbeat v3(Corosync)+Pacemaker+NFS+Httpd 实现Web服务器的高可用、Heartbeat v3(Corosync)+Pacemaker+NFS+mysql 实现MySQL服务器的高可用。总结一下，Keepalived中实现轻量级的高可用，一般用于前端高可用，且不需要共享存储，一般常用于两个节点的高可用。而Heartbeat(或Corosync)一般用于服务的高可用，且需要共享存储，一般用于多节点的高可用。这个问题我们说明白了。

那heartbaet与corosync又应该选择哪个好？
一般用corosync，因为corosync的运行机制更优于heartbeat，就连从heartbeat分离出来的pacemaker都说在以后的开发当中更倾向于corosync，所以现在corosync+pacemaker是最佳组合。

双机高可用一般是通过虚拟IP（飘移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：
//负载均衡器上配置的域名都解析到这个VIP上

应用环境如下：

http://nginx.org/download/nginx-1.9.7.tar.gz
[root@master-node src]# wget http://www.keepalived.org/software/keepalived-1.3.2.tar.gz
安装nginx
[root@master-node src]# tar -zvxf nginx-1.9.7.tar.gz
[root@master-node src]# 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@master-node nginx-1.9.7]# useradd www -M -s /sbin/nologin
[root@master-node 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
#CFLAGS="$CFLAGS -g"
[root@master-node 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@master-node nginx-1.9.7]# make && make install
安装keepalived
[root@master-node src]# tar -zvxf keepalived-1.3.2.tar.gz
[root@master-node src]# cd keepalived-1.3.2
[root@master-node keepalived-1.3.2]# ./configure
[root@master-node keepalived-1.3.2]# make && make install
[root@master-node keepalived-1.3.2]# cp /usr/local/src/keepalived-1.3.2/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
[root@master-node keepalived-1.3.2]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[root@master-node keepalived-1.3.2]# mkdir /etc/keepalived
[root@master-node keepalived-1.3.2]# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
[root@master-node keepalived-1.3.2]# cp /usr/local/sbin/keepalived /usr/sbin/
将nginx和keepalive服务加入开机启动服务
[root@master-node keepalived-1.3.2]# echo "/usr/local/nginx/sbin/nginx" >> /etc/rc.local
[root@master-node keepalived-1.3.2]# echo "/etc/init.d/keepalived start" >> /etc/rc.local

103.110.98.14 netmask 255.255.255.192 broadcast 103.110.98.63
inet6 fe80::46a8:42ff:fe17:3ddd prefixlen 64 scopeid 0x20<link>
ether 44:a8:42:17:3d:dd txqueuelen 1000 (Ethernet)
RX packets 133787818 bytes 14858530059 (13.8 GiB)
RX errors 0 dropped 644 overruns 0 frame 0
TX packets 2291619 bytes 426619870 (406.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 16
.......

接着开始绑定VIP（这一步其实可以不用这么直接在外部使用ifconfig绑定。Nginx或Haproxy+Keepalived的七层负载均衡的高可用环境中，VIP就直接在 Keepalived 的配置文件里配置就好，使用命令 ip addr 就能看出 vip；而LVS+Keepalived 四层负载均衡的高可用环境中， vip是要在外面单独设置的（即ifconfig eth0:0 ....的方式创建vip），通过 ifconfig 可以查看出来 vip。）

[root@master-node ~]# ifconfig em1:0 103.110.98.20 broadcast 103.110.98.63 netmask 255.255.255.192 up
[root@master-node ~]# route add -host 103.110.98.20 dev em1:0

查看VIP是否成功绑定了：
[root@master-node ~]# ifconfig
em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 103.110.98.14 netmask 255.255.255.192 broadcast 103.110.98.63
inet6 fe80::46a8:42ff:fe17:3ddd prefixlen 64 scopeid 0x20<link>
ether 44:a8:42:17:3d:dd txqueuelen 1000 (Ethernet)
RX packets 133789569 bytes 14858744709 (13.8 GiB)
RX errors 0 dropped 644 overruns 0 frame 0
TX packets 2291620 bytes 426619960 (406.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 16

em1:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 103.110.98.20 netmask 255.255.255.192 broadcast 103.110.98.63
ether 44:a8:42:17:3d:dd txqueuelen 1000 (Ethernet)
device interrupt 16
.......

[root@master-node ~]# ping 103.110.98.20
PING 103.110.98.20 (103.110.98.20) 56(84) bytes of data.
64 bytes from 103.110.98.20: icmp_seq=1 ttl=64 time=0.044 ms
64 bytes from 103.110.98.20: icmp_seq=2 ttl=64 time=0.036 ms

[root@master-node ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 103.10.86.1 0.0.0.0 UG 100 0 0 em1
103.10.86.0 0.0.0.0 255.255.255.192 U 100 0 0 em1
103.110.98.20 0.0.0.0 255.255.255.255 UH 0 0 0 em1
192.168.1.0 0.0.0.0 255.255.255.0 U 100 0 0 em2

setenforce 0 #使配置立即生效

[root@master-node ~]# vim /etc/sysconfig/iptables
.......
-A INPUT -s 103.110.98.0/24 -d 224.0.0.18 -j ACCEPT #允许组播地址通信
-A INPUT -s 192.168.1.0/24 -d 224.0.0.18 -j ACCEPT
-A INPUT -s 103.110.98.0/24 -p vrrp -j ACCEPT #允许 VRRP（虚拟路由器冗余协）通信
-A INPUT -s 192.168.1.0/24 -p vrrp -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT #开通80端口访问

[root@master-node ~]# /etc/init.d/iptables restart #重启防火墙使配置生效

master-node和slave-node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@master-node ~]# 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  \'$http_x_forwarded_for $remote_addr $remote_user [$time_local] "$request" \'
                      \'$status $body_bytes_sent "$http_referer" \'
                      \'"$http_user_agent" "$http_cookie" $host $request_time\';
 
    #######
    ## http setting
    #######
    sendfile       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;
 
    #
    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;
}

[root@master-node ~]# mkdir /usr/local/nginx/conf/vhosts
[root@master-node ~]# mkdir /var/www/cache
[root@master-node ~]# ulimit 65535

[root@master-node ~]# vim /usr/local/nginx/conf/vhosts/LB.conf
upstream LB-WWW {
      ip_hash;
      server 192.168.1.101:80 max_fails=3 fail_timeout=30s;     #max_fails = 3 为允许失败的次数，默认值为1
      server 192.168.1.102:80 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 192.168.1.118:80 max_fails=3 fail_timeout=30s;
    }
    
upstream LB-OA {
      ip_hash;
      server 192.168.1.101:8080 max_fails=3 fail_timeout=30s;
      server 192.168.1.102:8080 max_fails=3 fail_timeout=30s;
}
          
  server {
      listen      80;
      server_name dev.wangshibo.com;
    
      access_log  /usr/local/nginx/logs/dev-access.log main;
      error_log  /usr/local/nginx/logs/dev-error.log;
    
      location /svn {
         proxy_pass http://192.168.1.108/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://192.168.1.108/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  www.wangshibo.com;
  
      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  oa.wangshibo.com;
  
      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;
        }
}

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）首先在本机用IP访问上面LB.cong中配置的各个后端真实服务器的url
2）然后在本机用域名和路径访问上面LB.cong中配置的各个后端真实服务器的域名/虚拟路径

----------------------------------------------------------------------------------------------------------------------------
后端应用服务器的nginx配置，这里选择192.168.1.108作为例子进行说明
由于这里的192.168.1.108机器是openstack的虚拟机，没有外网ip，不能解析域名。
所以在server_name处也将ip加上，使得用ip也可以访问。
[root@108-server ~]# cat /usr/local/nginx/conf/vhosts/svn.conf
server {
listen 80;
#server_name dev.wangshibo.com;
server_name dev.wangshibo.com 192.168.1.108;

access_log /usr/local/nginx/logs/dev.wangshibo-access.log main;
error_log /usr/local/nginx/logs/dev.wangshibo-error.log;

location / {
root /var/www/html;
index index.html index.php index.htm;
}
}

[root@108-server ~]# ll /var/www/html/
drwxr-xr-x. 2 www www 4096 Dec 7 01:46 submin
drwxr-xr-x. 2 www www 4096 Dec 7 01:45 svn
[root@108-server ~]# cat /var/www/html/svn/index.html
this is the page of svn/192.168.1.108
[root@108-server ~]# cat /var/www/html/submin/index.html
this is the page of submin/192.168.1.108

[root@108-server ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.1.108 dev.wangshibo.com

[root@108-server ~]# curl http://dev.wangshibo.com //由于是内网机器不能联网，亦不能解析域名。所以用域名访问没有反应。只能用ip访问
[root@ops-server4 vhosts]# curl http://192.168.1.108
this is 192.168.1.108 page!!!
[root@ops-server4 vhosts]# curl http://192.168.1.108/svn/ //最后一个/符号要加上，否则访问不了。
this is the page of svn/192.168.1.108
[root@ops-server4 vhosts]# curl http://192.168.1.108/submin/
this is the page of submin/192.168.1.108
2.keepalived配置
1）master-node负载机上的keepalived配置（sendmail部署可以参考：linux下sendmail邮件系统安装操作记录）
[root@master-node ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master-node ~]# 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
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