Keepalived introduction and installation

keepalived brief introduction

Keepalived Is used to detect the state of the server , If a server goes down , Or work breakdown ,Keepalived Will detect , And remove the faulty server from the system , At the same time, use other servers to replace the work of this server , When the server is working Keepalived Automatically add servers to the server cluster , All this work is done automatically , There is no need for human intervention , All you need to do is fix the failed server . Official website ： Keepalived Yes, it is C Programming language routing software . The main objective of the project is to Linux System and based on Linux Our infrastructure provides simple and powerful projects with load balancing and high availability . If we say network failure or itself keepalived After hanging up , Pre configured master slaver1 slaver2…

install keepalived, Configure the load balancing server

Installation configuration yum -y install keepalived
Host configuration vi /etc/keepalived/keepalived.conf
SMTP（Simple Mail Transfer Protocol） Simple Mail Transfer Protocol , It's a set of rules for sending mail from source to destination , It controls the way letters are transferred .

shell Script

vim /usr/local/nginx/conf/nginx.conf

#!/bin/bash
PSNUM=`ps -C nginx --no-header|wc -l`
if [ $PSNUM -eq 0 ];then
/usr/local/nginx/sbin/nginx
if [ `ps -C nginx --no-header|wc -l` -eq 0 ]; then
     killall keepalived
 fi
fi

Host configuration ：

vim /etc/keepalived/check-nginx.sh
1
1
 global_defs {

notification_email {

 [email protected]

}

notification_email_from [email protected]   # Who is the email source address when sending notification email 

smtp_server 127.0.0.1

smtp_connect_timeout 30 # Connect smtp Connection timeout 

router_id LVS_DEVEL  # Machine identification 

}

# It's for health check ups , At that time, when the inspection fails, it will vrrp_instance Of priority Reduce the corresponding value .

vrrp_script chk_http_port {

       script "/usr/checknginx.sh"       # Monitoring script 

       interval 2                                         # Monitoring script detection cycle seconds 

       weight  10       # It means if script in   The instruction execution of failed ,
        So the corresponding vrrp_instance The priority of will be reduced 10 A little bit 
    }

vrrp_instance VI_1 {

state MASTER #backup The machine is configured to BACKUP

interface eth0     # Bound network card name 

virtual_router_id  51  # Must be with backup The machine configuration is the same 

priority 100  # priority , than backup Machine height at least 50

advert_int 1 # Check interval , Default 1 second  VRRP The sending cycle of heartbeat packets , Unit is s

authentication {

    auth_type PASS  # Type of Authorization , Must be with backup identical 

    auth_pass 1111   # Authorization code , Must be with backup identical 

} 

virtual_ipaddress {

    192.168.23.220    # fictitious ip Address , Must be with backup identical 

}

track_script {

               chk_http_port

} 

}

Standby configuration

global_defs {

notification_email {

 [email protected]

}

notification_email_from [email protected]

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL_BAK

}

vrrp_script chk_http_port {

       script "/usr/checknginx.sh"       # Monitoring script 

       interval 2                                         # Monitor script detection cycle 

       weight -10                                          # It means if script Instruction execution in failed , So the corresponding vrrp_instance The priority of will be reduced 10 A little bit .

    }

vrrp_instance VI_1 {

state BACKUP

interface eth0

virtual_router_id 51

priority 50

advert_int 1

 authentication {

    auth_type PASS  # Type of Authorization , Must be with backup identical 

    auth_pass 1111   # Authorization code , Must be with backup identical 

} 

virtual_ipaddress {

    192.168.23.220    # fictitious ip Address , Must be with backup identical 

}

 track_script {

               chk_http_port

} 

nopreempt   # Don't take IP, When keepalived After switching , It can only be configured in BACKUP On  ,

                                                    # This avoids the overhead of switching back and forth , It also avoids IP System instability caused by switching 

}