keepalived实现nginx负载均衡机高可用

事愿人为 2023-03-28 原文

keepalived实现nginx负载均衡机高可用

keepalived实现nginx负载均衡机高可用

环境说明：

系统	主机名	IP	服务
centos8	master	192.168.111.141	nginx keepalived
centos8	backup	192.168.111.142	nginx keepalived
centos8	apache	192.168.111.143	httpd
centos8	nginx	192.168.111.144	nginx

配置web界面

apache

//修改名字
[root@localhost ~]# hostnamectl set-hostname apache
[root@localhost ~]# bash
[root@apache ~]# 

//关闭防火墙和selinux
[root@apache ~]# setenforce 0
[root@apache ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@apache ~]# systemctl disable --now firewalld
[root@apache ~]# reboot

//配置yum源
[root@apache ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
[root@apache ~]# sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

//安装apache,主页内容为apache
[root@apache ~]# yum -y install httpd
[root@apache ~]# echo "apache" > /var/www/html/index.html
[root@apache ~]# systemctl enable --now httpd
[root@apache ~]# ss -anlt
State        Recv-Q        Send-Q               Local Address:Port               Peer Address:Port       Process       
LISTEN       0             128                        0.0.0.0:22                      0.0.0.0:*                        
LISTEN       0             128                              *:80                            *:*                        
LISTEN       0             128                           [::]:22                         [::]:*                        
[root@apache ~]# curl 192.168.111.143
apache

nginx

//修改名字
[root@localhost ~]# hostnamectl set-hostname nginx
[root@localhost ~]# bash
[root@nginx ~]# 

//关闭防火墙和selinux
[root@nginx ~]# setenforce 0
[root@nginx ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@nginx ~]# systemctl disable --now firewalld
[root@nginx ~]# reboot

//配置yum源
[root@nginx ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
[root@nginx ~]# sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

//安装nginx,主页内容为nginx
[root@nginx ~]# yum -y install nginx
[root@nginx ~]# echo "nginx" > /usr/share/nginx/html/index.html
[root@nginx ~]# systemctl enable --now nginx
[root@nginx ~]# ss -anlt
State        Recv-Q        Send-Q               Local Address:Port               Peer Address:Port       Process       
LISTEN       0             128                        0.0.0.0:80                      0.0.0.0:*                        
LISTEN       0             128                        0.0.0.0:22                      0.0.0.0:*                        
LISTEN       0             128                           [::]:80                         [::]:*                        
LISTEN       0             128                           [::]:22                         [::]:*                        
[root@nginx ~]# curl 192.168.111.144
nginx

配置nginx负载均衡

master

//修改名字
[root@localhost ~]# hostnamectl set-hostname master
[root@localhost ~]# bash
[root@master ~]# 

//关闭防火墙和selinux
[root@master ~]# setenforce 0
[root@master ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@master ~]# systemctl disable --now firewalld
[root@master ~]# reboot

//配置yum源
[root@master ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
[root@master ~]# sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

//创建用户
[root@master ~]# useradd -rMs /sbin/nologin nginx

//安装依赖包
[root@master ~]# dnf -y install pcre-devel openssl openssl-devel gd-devel gcc gcc-c++ make wget vim

//编译安装nginx
[root@backup ~]# wget http://nginx.org/download/nginx-1.22.0.tar.gz
[root@master ~]# tar xf nginx-1.22.0.tar.gz 
[root@master ~]# cd nginx-1.22.0
[root@master nginx-1.22.0]# ./configure \
 --prefix=/usr/local/nginx \
 --user=nginx \
 --group=nginx \
 --with-debug \
 --with-http_ssl_module \
 --with-http_realip_module \
 --with-http_gunzip_module \
 --with-http_gzip_static_module \
 --with-http_stub_status_module
 [root@master nginx-1.22.0]# make -j $(grep 'processor' /proc/cpuinfo | wc -l) && make install

//配置环境变量
[root@master ~]# echo "export PATH=$PATH:/usr/local/nginx/sbin" > /etc/profile.d/nginx.sh
[root@master ~]# source /etc/profile.d/nginx.sh
                
//配置system启动服务
[root@master ~]# vim /usr/lib/systemd/system/nginx.service
[Unit]
Description=nginx server daemon
After=network.target 
 
[Service]
Type=forking
ExecStart=/usr/local/nginx/sbin/nginx
ExecStop=/usr/local/nginx/sbin/nginx -s stop
ExecReload=/bin/kill -HUP \$MAINPID
 
[Install]
WantedBy=multi-user.target
[root@nginx ~]# systemctl daemon-reload

//启动nginx
[root@master ~]# systemctl enable --now nginx
[root@master ~]# ss -anlt
State        Recv-Q       Send-Q               Local Address:Port               Peer Address:Port       Process       
LISTEN       0            128                        0.0.0.0:80                      0.0.0.0:*                        
LISTEN       0            128                        0.0.0.0:22                      0.0.0.0:*                        
LISTEN       0            128                           [::]:22                         [::]:*               

//修改配置文件,配置负载均衡
[root@master ~]# vim /usr/local/nginx/conf/nginx.conf
    upstream web {				//http字段内
    server 192.168.111.143;
    server 192.168.111.144;
    }
    .........
        location / {				//修改配置文件
        root html;
        proxy_pass   http://web;
        }
[root@master ~]# systemctl restart nginx

//查看负载均衡效果
[root@master ~]# curl 192.168.111.141
apache
[root@master ~]# curl 192.168.111.141
nginx
[root@master ~]# curl 192.168.111.141
apache
[root@master ~]# curl 192.168.111.141
nginx

backup

//修改名字
[root@localhost ~]# hostnamectl set-hostname backup
[root@localhost ~]# bash
[root@backup ~]# 

//关闭防火墙和selinux
[root@backup ~]# setenforce 0
[root@backup ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@backup ~]# systemctl disable --now firewalld
[root@backup ~]# reboot

//配置yum源
[root@backup ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
[root@backup ~]# sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

//创建用户
[root@backup ~]# useradd -rMs /sbin/nologin nginx

//安装依赖包
[root@backup ~]# dnf -y install pcre-devel openssl openssl-devel gd-devel gcc gcc-c++ make wget vim

//编译安装nginx
[root@backup ~]# wget http://nginx.org/download/nginx-1.22.0.tar.gz
[root@backup ~]# tar xf nginx-1.22.0.tar.gz 
[root@backup ~]# cd nginx-1.22.0
[root@backup nginx-1.22.0]# ./configure \
 --prefix=/usr/local/nginx \
 --user=nginx \
 --group=nginx \
 --with-debug \
 --with-http_ssl_module \
 --with-http_realip_module \
 --with-http_gunzip_module \
 --with-http_gzip_static_module \
 --with-http_stub_status_module
[root@backup nginx-1.22.0]# make -j $(grep 'processor' /proc/cpuinfo | wc -l) && make install

//配置环境变量
[root@backup ~]# echo "export PATH=$PATH:/usr/local/nginx/sbin" > /etc/profile.d/nginx.sh
[root@backup ~]# source /etc/profile.d/nginx.sh
                
//配置system启动服务
[root@backup ~]# vim /usr/lib/systemd/system/nginx.service
[Unit]
Description=nginx server daemon
After=network.target 
 
[Service]
Type=forking
ExecStart=/usr/local/nginx/sbin/nginx
ExecStop=/usr/local/nginx/sbin/nginx -s stop
ExecReload=/bin/kill -HUP \$MAINPID
 
[Install]
WantedBy=multi-user.target
[root@backup ~]# systemctl daemon-reload

//启动nginx
[root@backup ~]# systemctl enable --now nginx
[root@backup ~]# ss -anlt
State        Recv-Q        Send-Q               Local Address:Port               Peer Address:Port       Process       
LISTEN       0             128                        0.0.0.0:80                      0.0.0.0:*                        
LISTEN       0             128                        0.0.0.0:22                      0.0.0.0:*                        
LISTEN       0             128                           [::]:22                         [::]:*                        

//修改配置文件,配置负载均衡
[root@backup ~]# vim /usr/local/nginx/conf/nginx.conf
    upstream web {				//http字段内
    server 192.168.111.143;
    server 192.168.111.144;
    }
    .........
        location / {				//修改配置文件
        root html;
        proxy_pass   http://web;
        }
[root@backup ~]# systemctl restart nginx

//查看负载均衡效果
[root@backup ~]# curl 192.168.111.142
apache
[root@backup ~]# curl 192.168.111.142
nginx
[root@backup ~]# curl 192.168.111.142
apache
[root@backup ~]# curl 192.168.111.142
nginx

配置keepalived高可用

master

//首先安装keepalived
[root@master ~]# yum -y install keepalived
 
//编辑配置文件，并启动服务
[root@master ~]# mv /etc/keepalived/keepalived.conf{,.bak}
[root@master ~]# vim /etc/keepalived/keepalived.conf 
! Configuration File for keepalived
 
global_defs {
   router_id lb01
}
 
vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.111.250
    }
}
 
virtual_server 192.168.111.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP
 
    real_server 192.168.111.141 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
 
    real_server 192.168.111.142 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@master ~]# systemctl enable --now keepalived

//通过虚拟IP访问
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:50:34:72 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.141/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 1500sec preferred_lft 1500sec
    inet 192.168.111.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe50:3472/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
 
//通过虚拟ip访问
//一定要把backup端的nginx服务关掉才能访问，

[root@master ~]# curl 192.168.111.250
apache
[root@master ~]# curl 192.168.111.250
nginx
[root@master ~]# curl 192.168.111.250
apache
[root@master ~]# curl 192.168.111.250
nginx

backup

//首先安装keepalived
[root@backup ~]# dnf -y install keepalived
 
//编辑配置文件，并启动服务
[root@backup ~]# mv /etc/keepalived/keepalived.conf{,.back}
[root@backup ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
 
global_defs {
   router_id lb02
}
 
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.111.250
    }
}
 
virtual_server 192.168.111.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP
 
    real_server 192.168.111.141 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
 
    real_server 192.168.111.142 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@backup ~]# systemctl enable --now keepalived

编写脚本

master

[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# vim check_nginx.sh
#!/bin/bash
nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
if [ $nginx_status -lt 1 ];then
    systemctl stop keepalived
fi

[root@master scripts]# vim notify.sh
#!/bin/bash
VIP=$2
case "$1" in
  master)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -lt 1 ];then
            systemctl start nginx
        fi
  ;;
  backup)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -gt 0 ];then
            systemctl stop nginx
        fi
  ;;
  *)
        echo "Usage:$0 master|backup VIP"
  ;;
esac
[root@master scripts]# chmod +x check_haproxy.sh notify.sh

backup

[root@backup ~]# mkdir /scripts
[root@backup ~]# cd /scripts/
[root@backup scripts]# scp root@192.168.111.141:/scripts/notify.sh .

配置keepalived加入监控脚本的配置

master

[root@master ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
 
global_defs {
   router_id lb01
}
 
vrrp_script nginx_check {				//添加
    script "/scripts/check_nginx.sh"
    interval 1
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.111.250
    }
    track_script {			//添加
        haproxy_check
    }
    notify_master "/scripts/notify.sh master 192.168.111.250"
}
 
virtual_server 192.168.111.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP
 
    real_server 192.168.111.141 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
 
    real_server 192.168.111.142 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@master scripts]# systemctl restart keepalived

backup

[root@backup ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
 
global_defs {
   router_id lb02
}
 
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.111.250
    }
    notify_master "/scripts/notify.sh master 192.168.111.250"		//添加
    notify_backup "/scripts/notify.sh backup 192.168.111.250"
}
 
virtual_server 192.168.111.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP
 
    real_server 192.168.111.141 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
 
    real_server 192.168.111.142 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@backup ~]# systemctl restart keepalived

测试

模拟nginx服务故障

//master端
[root@master ~]# curl 192.168.111.250
apache
[root@master ~]# curl 192.168.111.250
nginx
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:50:34:72 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.141/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 1601sec preferred_lft 1601sec
    inet 192.168.111.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe50:3472/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@master ~]# systemctl stop nginx
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:50:34:72 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.141/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 1591sec preferred_lft 1591sec
    inet6 fe80::20c:29ff:fe50:3472/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

//backup端
[root@backup ~]# systemctl start nginx    //前面把服务关了这里启动一下
[root@backup ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:07:42:65 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.142/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 947sec preferred_lft 947sec
    inet 192.168.111.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe07:4265/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@backup ~]# curl 192.168.111.250
apache
[root@backup ~]# curl 192.168.111.250
nginx
[root@backup ~]# curl 192.168.111.250
apache
[root@backup ~]# curl 192.168.111.250
nginx

启动master端的nginx服务

//master端
[root@master scripts]# systemctl start nginx
[root@master scripts]# systemctl restart keepalived
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:50:34:72 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.141/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 1223sec preferred_lft 1223sec
    inet 192.168.111.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe50:3472/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

//backup端
[root@backup ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:07:42:65 brd ff:ff:ff:ff:ff:ff
    inet 192.168.111.142/24 brd 192.168.111.255 scope global dynamic noprefixroute ens33
       valid_lft 1632sec preferred_lft 1632sec
    inet6 fe80::20c:29ff:fe07:4265/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

有关keepalived实现nginx负载均衡机高可用的更多相关文章

ruby-on-rails - 如何优雅地重启 thin + nginx？ - 2
我的瘦服务器配置了nginx，我的ROR应用程序正在它们上运行。在我发布代码更新时运行thinrestart会给我的应用程序带来一些停机时间。我试图弄清楚如何优雅地重启正在运行的Thin实例，但找不到好的解决方案。有没有人能做到这一点？最佳答案 #Restartjustthethinserverdescribedbythatconfigsudothin-C/etc/thin/mysite.ymlrestartNginx将继续运行并代理请求。如果您将Nginx设置为使用多个上游服务器，例如server{listen80;server
ruby - 如何根据特征实现 FactoryGirl 的条件行为 - 2
我有一个用户工厂。我希望默认情况下确认用户。但是鉴于unconfirmed特征，我不希望它们被确认。虽然我有一个基于实现细节而不是抽象的工作实现，但我想知道如何正确地做到这一点。factory:userdoafter(:create)do|user,evaluator|#unwantedimplementationdetailshereunlessFactoryGirl.factories[:user].defined_traits.map(&:name).include?(:unconfirmed)user.confirm!endendtrait:unconfirmeddoenden
ruby-on-rails - 如何使辅助方法在 Rails 集成测试中可用？ - 2
我在app/helpers/sessions_helper.rb中有一个帮助程序文件，其中包含一个方法my_preference，它返回当前登录用户的首选项。我想在集成测试中访问该方法。例如，这样我就可以在测试中使用getuser_path(my_preference)。在其他帖子中，我读到这可以通过在测试文件中包含requiresessions_helper来实现，但我仍然收到错误NameError:undefinedlocalvariableormethod'my_preference'.我做错了什么？require'test_helper'require'sessions_hel
华为OD机试用Python实现 -【明明的随机数】 2023Q1A - 2
华为OD机试题本篇题目：明明的随机数题目输入描述输出描述：示例1输入输出说明代码编写思路最近更新的博客华为od2023|什么是华为od，od薪资待遇，od机试题清单华为OD机试真题大全，用Python解华为机试题|机试宝典【华为OD机试】全流程解析+经验分享,题型分享,防作弊指南华为o
基于C#实现简易绘图工具【100010177】 - 2
C#实现简易绘图工具一.引言实验目的:通过制作窗体应用程序(C#画图软件),熟悉基本的窗体设计过程以及控件设计,事件处理等,熟悉使用C#的winform窗体进行绘图的基本步骤,对于面向对象编程有更加深刻的体会.Tutorial任务设计一个具有基本功能的画图软件**·包括简单的新建文件,保存,重新绘图等功能**·实现一些基本图形的绘制,包括铅笔和基本形状等,学习橡皮工具的创建**·设计一个合理舒适的UI界面**注明:你可能需要先了解一些关于winform窗体应用程序绘图的基本知识,以及关于GDI+类和结构的知识二.实验环境Windows系统下的visualstudio2017C#窗体应用程序三.
MIMO-OFDM无线通信技术及MATLAB实现（1）无线信道：传播和衰落 - 2
MIMO技术的优缺点优点通过下面三个增益来总体概括：阵列增益。阵列增益是指由于接收机通过对接收信号的相干合并而活得的平均SNR的提高。在发射机不知道信道信息的情况下，MIMO系统可以获得的阵列增益与接收天线数成正比复用增益。在采用空间复用方案的MIMO系统中，可以获得复用增益，即信道容量成倍增加。信道容量的增加与min(Nt,Nr)成正比分集增益。在采用空间分集方案的MIMO系统中，可以获得分集增益，即可靠性性能的改善。分集增益用独立衰落支路数来描述，即分集指数。在使用了空时编码的MIMO系统中，由于接收天线或发射天线之间的间距较远，可认为它们各自的大尺度衰落是相互独立的，因此分布式MIMO
【Java入门】使用Java实现文件夹的遍历 - 2
遍历文件夹我们通常是使用递归进行操作，这种方式比较简单，也比较容易理解。本文为大家介绍另一种不使用递归的方式，由于没有使用递归，只用到了循环和集合，所以效率更高一些！一、使用递归遍历文件夹整体思路1、使用File封装初始目录，2、打印这个目录3、获取这个目录下所有的子文件和子目录的数组。4、遍历这个数组，取出每个File对象4-1、如果File是否是一个文件，打印4-2、否则就是一个目录，递归调用代码实现publicclassSearchFile{publicstaticvoidmain(String[]args){//初始目录Filedir=newFile("d:/Dev");Datebeg
ruby - Arrays Sets 和 SortedSets 在 Ruby 中是如何实现的 - 2
通常，数组被实现为内存块，集合被实现为HashMap，有序集合被实现为跳跃列表。在Ruby中也是如此吗？我正在尝试从性能和内存占用方面评估Ruby中不同容器的使用情况最佳答案数组是Ruby核心库的一部分。每个Ruby实现都有自己的数组实现。Ruby语言规范只规定了Ruby数组的行为，并没有规定任何特定的实现策略。它甚至没有指定任何会强制或至少建议特定实现策略的性能约束。然而，大多数Rubyist对数组的性能特征有一些期望，这会迫使不符合它们的实现变得默默无闻，因为实际上没有人会使用它:插入、前置或追加以及删除元素的最坏情况步骤复
ruby - "public/protected/private"方法是如何实现的，我该如何模拟它？ - 2
在ruby中，你可以这样做:classThingpublicdeff1puts"f1"endprivatedeff2puts"f2"endpublicdeff3puts"f3"endprivatedeff4puts"f4"endend现在f1和f3是公共(public)的，f2和f4是私有(private)的。内部发生了什么，允许您调用一个类方法，然后更改方法定义？我怎样才能实现相同的功能(表面上是创建我自己的java之类的注释)例如...classThingfundeff1puts"hey"endnotfundeff2puts"hey"endendfun和notfun将更改以下函数定
ruby-on-rails - 如何用不同的用户运行nginx主进程 - 2
A/ctohttp://wiki.nginx.org/CoreModule#usermaster进程曾经以root用户运行，是否可以以不同的用户运行nginxmaster进程？最佳答案只需以非root身份运行init脚本(即/etc/init.d/nginxstart)，就可以用不同的用户运行nginxmaster进程。如果这真的是你想要做的，你将需要确保日志和pid目录(通常是/var/log/nginx&/var/run/nginx.pid)对该用户是可写的，并且您所有的listen调用都是针对大于1024的端口(因为绑定(

keepalived实现nginx负载均衡机高可用

keepalived实现nginx负载均衡机高可用

配置web界面

配置nginx负载均衡

配置keepalived高可用

编写脚本

配置keepalived加入监控脚本的配置

测试

有关keepalived实现nginx负载均衡机高可用的更多相关文章

随机推荐