如何在FreeBSD上搭建一个高可用的Keepalived Nginx Web集群？

搭建Keepalived Nginx高可用Web集群的步骤如下：

1、安装FreeBSD操作系统

2、更新系统软件包

pkg update && pkg upgrade

3、安装必要的软件包

pkg install nginx keepalived

4、配置Nginx

编辑/usr/local/etc/nginx/nginx.conf文件，设置以下内容：

http {
    server {
        listen 80;
        server_name example.com;
        location / {
            root /usr/local/www/nginx/html;
            index index.html index.htm;
        }
    }
}

将example.com替换为您的域名。

5、创建Nginx网站根目录并添加测试文件

mkdir p /usr/local/www/nginx/html
echo "Hello, World!" > /usr/local/www/nginx/html/index.html

6、配置Keepalived

编辑/usr/local/etc/keepalived/keepalived.conf文件，设置以下内容：

vrrp_script chk_nginx {
    script "/usr/local/bin/check_nginx"
    interval 2
    weight 2
}
vrrp_instance VI_1 {
    interface eth0
    state MASTER
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.100
    }
    track_script {
        chk_nginx
    }
}

将eth0替换为您的网络接口名称，将192.168.1.100替换为您的虚拟IP地址。

7、创建检查Nginx状态的脚本

cat << EOF > /usr/local/bin/check_nginx
#!/bin/sh
if pgrep "nginx" > /dev/null; then
    exit 0
else
    exit 1
fi
EOF
chmod +x /usr/local/bin/check_nginx

8、启动Nginx和Keepalived服务

service nginx start
service keepalived start

9、配置防火墙允许HTTP和VRRP流量

sysctl net.inet.ip.fw.enable=1
sysctl net.inet.ip.fw.one_pass=1
sysctl net.inet.ip.fw.add="/etc/ipfw.conf"
echo "fwcmd="/etc/ipfw.conf"" >> /etc/rc.conf
echo "fwcmd="/etc/ipfw.conf"" >> /etc/rc.conf.local
echo "pass inet proto tcp from any to any port 80 keepstate" > /etc/ipfw.conf
echo "pass inet proto udp from any to any port 112 keepstate" >> /etc/ipfw.conf

至此，您已经成功搭建了一个基于Keepalived和Nginx的高可用Web集群，当主服务器出现故障时，Keepalived会自动将虚拟IP切换到备用服务器，从而实现高可用性。