keepalived+nginx+http省钱到家

不知道是不是架构师方面觉得服务器越少就越省钱，反正原先的4台服务器作一个服务的负载都觉得浪费。所以就出现了两台服务器作负载和服务的需求。
研究做过几次尝试
1.keepalived+ipvsadm+http，负载会失败。
2.keepalived+http，只能作vip，主备形式提供，流量只会到keepalive主的服务器上。只有障碍切换才会跑到备的主机上。
3.keepalived+nginx+http，这样可以提供轮询式的访问，但是要注意的是客户端无法再用http原来的端口访问，要在nginx上改变访问的端口。所以这种省钱方式其实还是不靠谱的。

但如果是前端程序访问后端服务可以自定义访问端口的情况下，这种方式起码让自己的成本帐面上省了一半

1.环境说明

ip	作用
192.168.20.99	vip
192.168.20.11	keepalived(主)+nginx+http服务器
192.168.20.12	keepalived(备)+nginx+http服务器

2.keepalived，nginx，http的安装

在有yum源的情况下，keepalived和httpd都可以通过yum安装

yum install -y keepalived httpd

nginx稍微麻烦一点，需要编译
编译环境安装

yum -y install make zlib zlib-devel gcc-c++ libtool  openssl openssl-devel

下载nginx源码包并安装，这里要用到upstream这个模块，地址为http://nginx.org/en/download.html

tar -xzvf nginx-1.15.6.tar.gz
cd nginx-1.15.6
./configure --with-stream && make && make install
ln -s /usr/local/nginx/sbin/nginx /usr/bin/nginx
nginx -v #正确显示版本号以后说明nginx可以正常使用

keepalived的配置文件
192.168.20.11（主）上的配置文件

vip="192.168.20.99"
cat <<EOF>/etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
    state MASTER
    interface enp0s8
    virtual_router_id 99
    priority 100
    advert_int 1
       authentication {
          auth_type PASS
          auth_pass 1111
       }
       virtual_ipaddress {
                          $vip
      }
}
EOF

192.168.20.12（备)上的配置文件

vip="192.168.20.99"
cat <<EOF>/etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
    state BACKUP
    interface enp0s8
    virtual_router_id 99
    priority 80
    advert_int 1
       authentication {
          auth_type PASS
          auth_pass 1111
       }
       virtual_ipaddress {
                          $vip
      }
}
EOF

启动keepalived并加入开机启动

systemctl start keepalived && systemctl enable keepalived

keepalived备机添加本地回路
添加是为了备机的nginx有相应的ip可以监听，不然没有vip监听，nginx无法启动

ip addr add 192.168.20.99/32 dev lo
#可以加入开机启动
chmod 755 /etc/rc.d/rc.local
echo "ip addr add 192.168.20.99 dev lo">>/etc/rc.local

httpd的主页文件（为了方便测试，把主机名写入index.html）

echo "my name is `hostname`">/var/www/html/index.html

启动httpd

systemctl start httpd && systemctl enable httpd

nginx的配置文件
以下配置文件中前端访问端口变为了88，如果还是80的话，因为http 80 占用，nginx是无法绑定的。

cat <<EOF>/usr/local/nginx/conf/nginx.conf
worker_processes 1;
worker_rlimit_nofile 200000;
events {
    worker_connections 120000;
}
stream {
    include /etc/nginx/stream/*.stream;
}
EOF

[ -d /etc/nginx/stream ] || mkdir -p /etc/nginx/stream

cat <<EOF>/etc/nginx/stream/192.168.20.99_80.stream
upstream 192.168.20.99_80 {
    server 192.168.20.11:80 weight=10;
    server 192.168.20.12:80 weight=10;
}
server {
    listen 192.168.20.99:88;
    proxy_connect_timeout 1s;
    proxy_timeout 30s;
    proxy_pass 192.168.20.99_80;
}
EOF

语法检查，如果没有问题就启动nginx

nginx -t
nginx
# 加入开机启动项
chmod 755 /etc/rc.d/rc.local
echo "nginx" >>/etc/rc.local

3.测试

注意访问的是88端口

myname@mypc:~/testbox$ for i in `seq 1 5`;do curl 192.168.20.99:88;done
my name is test1
my name is test2
my name is test1
my name is test2
my name is test1