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一，Keepalived
- Introduction
Second, build LVS+Keepalived
- Main scheduler configuration:
- Backup scheduler configuration:
Three, hyperlinks (build web, nfs)
Fourth, verify LVS+Keepalived

一，Keepalived

Solve the danger of a single server bearing a single point of failure in the application

Introduction

A health check tool specially designed for LVS and HA

Support automatic failover
Support node health check
Official website: http://www.keepalived.org/

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Second, build LVS+Keepalived

VRRP (Virtual Routing Redundancy Protocol) is a backup solution for routers
Keepalived can realize multi-machine hot backup, each hot backup group can have multiple servers
We are dual-system hot backup. The failover of dual-system hot backup is realized by the drift of virtual ip address, which is suitable for various application servers.

Prepare the environment:

Based on the operation of LVS-DR, a standby scheduler was added, and the configuration was changed.


Master scheduler:	192.168.100.25 vip address: ens33:0 192.168.100.100
Standby scheduler:	192.168.100.29
web1：	192.168.100.26 vip address: lo:0 192.168.100.100
web2：	192.168.100.27 vip address: lo:0 192.168.100.100
nfs storage:	192.168.100.28

Main scheduler configuration:

1. Install Keepalived ipvsadm

root@localhost ~]# yum -y install keepalived ipvsadm

2. Configure the keepalived.conf configuration file

[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bakup
[root@localhost keepalived]# vi keepalived.conf
global_defs {
    
    
   router_id HA_TEST_R1
}
vrrp_instance VI_1 {
    
    
   state MASTER
   interface ens33
   virtual_router_id 1
   priority 100
   advert_int 1
   authentication {
    
    
      auth_type PASS
      auth_pass 123456
   }
   virtual_ipaddress {
    
    
      192.168.100.100
   }
}

virtual_server 192.168.100.100 80 {
    
    
    delay_loop 15
    lb_algo rr
    lb_kind DR
    persistence 60
    protocol TCP

    real_server 192.168.100.26 80 {
    
    
        weight 1
        TCP_CHECK {
    
    
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }
    real_server 192.168.100.27 80 {
    
    
        weight 1
        TCP_CHECK {
    
    
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }

Regional configuration module explanation:
global_defs {: define the router_id of this router
vrrp_instance VI_1 {: define the VRRP hot standby real column
virtual_ipaddress {: define the drift address (VIP), which can be multiple
virtual_server 192.168.100.10 80 {: define the virtual server address ( VIP), port
real_server 192.168.100.26 80 {: Define the address and port of the WEB site

3. Start keepalived and self-start after boot, ipvsadm

systemctl start keepalived    
systemctl enable keepalived
systemctl enable ipvsadm

4. Configure the vip address 192.168.100.100

[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@localhost network-scripts]# vi ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.100.100
NETMASK=255.255.255.255
ONBOOT=yes

ifup lo:0     #开启lo:0
ifconfig

5. View the load strategy under configuration

[root@localhost ]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.100:80 rr
  -> 192.168.100.26:80            Route   1      0          0         
  -> 192.168.100.27:80            Route   1      0          0

6. View VIP information

ip addr show

 ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:da:8c:3c brd ff:ff:ff:ff:ff:ff
    inet 《192.168.100.25/24》 brd 192.168.100.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 《192.168.100.100/32》scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::a33e:6402:8d1:c2aa/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

7. Adjust the /proc response parameters (optimized kernel parameters)

vi /etc/sysctl.conf 

net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0

sysctl  -p

Backup scheduler configuration:

We only need to configure the keepalive configuration file to set priority to upgrade, router_id, bakup (backup)
LVS scheduling rules are also in the keepalived.conf configuration file, which can be directly generated

1. Install Keepalived ipvsadm

root@localhost ~]# yum -y install keepalived ipvsadm

2. Configure the keepalived.conf configuration file

[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bakup
[root@localhost keepalived]# vi keepalived.conf

global_defs {
    
    
   router_id HA_TEST_R2
}
vrrp_instance VI_1 {
    
    
   state BACKUP
   interface ens33
   virtual_router_id 1
   priority 99
   advert_int 1
   authentication {
    
    
      auth_type PASS
      auth_pass 123456
   }
   virtual_ipaddress {
    
    
      192.168.100.100
   }
}

virtual_server 192.168.100.100 80 {
    
    
    delay_loop 15
    lb_algo rr
    lb_kind DR
    persistence 60
    protocol TCP

    real_server 192.168.100.26 80 {
    
    
        weight 1
        TCP_CHECK {
    
    
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }
    real_server 192.168.100.27 80 {
    
    
        weight 1
        TCP_CHECK {
    
    
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 4
        }
    }
}

3. Start keepalived and self-start after boot, ipvsadm

systemctl start keepalived    
systemctl enable keepalived
systemctl enable ipvsadm

4. View the load strategy under configuration

[root@localhost ]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.100:80 rr
  -> 192.168.100.26:80            Route   1      0          0         
  -> 192.168.100.27:80            Route   1      0          0

Three, hyperlinks (build web, nfs)

There are still three servers that are not configured (web1, web2, nfs storage)
web server and nfs storage service, see the LVS-DR mode deployment of the blogger classification load cluster.
Refer to the web and nfs part of the steps. Here is the hyperlink:
link: see web, Steps to build nfs storage...

Fourth, verify LVS+Keepalived

After verifying by cmd, whether to do failover, VIP address transfer! !

1. First verify that it is normal:
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2. Keep pinging the vip address; let the main scheduler disconnect and see if the mac address changes and the vip address drifts

3. Check whether the VIP address drifts to the standby scheduler