keepalived - Virtual is not routing my requests to real servers

Solution 1:

I understand from you question and the comments that the load balancers and the real servers are the same machines.

According to the Redhat documentation:

Accessing the virtual IP from the load balancers or one of the real servers is not supported. Likewise, configuring a load balancer on the same machines as a real server is not supported.

However, this is still possible according to the LVS Knowledge Base, but requires a bit more configuration effort.

Based on your example, let's take a 3 nodes setup without track script with one virtual IP address for keepalived-2.0.19 on CentOS 7:

• virtual IP address: 192.168.178.201
• node 1: 192.168.178.210 with priority 150
• node 2: 192.168.178.211 with priority 100
• node 3: 192.168.178.212 with priority 50

Then a possible configuration for keepalived is:

On node 1

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 150
    advert_int 1
    virtual_ipaddress {
        192.168.178.201/32
    }
}

virtual_server 192.168.178.201 {
    lvs_sched rr
    lvs_method DR
    protocol TCP
    persistence_timeout 50
    delay_loop 10
    real_server 192.168.178.210 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
    real_server 192.168.178.211 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
    real_server 192.168.178.212 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
}

On node 2

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    virtual_ipaddress {
        192.168.178.201/32
    }
}

virtual_server 192.168.178.201 {
    lvs_sched rr
    lvs_method DR
    protocol TCP
    persistence_timeout 50
    delay_loop 10
    real_server 192.168.178.211 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
    real_server 192.168.178.212 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
}

On node 3

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 50
    advert_int 1
    virtual_ipaddress {
        192.168.178.201/32
    }
}

virtual_server 192.168.178.201 {
    lvs_sched rr
    lvs_method DR
    protocol TCP
    persistence_timeout 50
    delay_loop 10
    real_server 192.168.178.212 {
        TCP_CHECK {
          connect_timeout 5
          connect_port 8443
        }
    }
}

NB: each node has LVS configured according to its priority (less and less real_server). If you configure LVS symmetrically, packets are going to be sent back and forth infinitely between the nodes and never answered.

You need to add the virtual IP address as a loopback address on all nodes. Otherwise, the BACKUP nodes receive the TCP messages from the load balancer but do not know what to do with it.

On all nodes in /etc/sysconfig/network-scripts/ifcfg-lo:0

DEVICE=lo:0
IPADDR=192.168.178.201
NETMASK=255.255.255.255
ONBOOT=yes
NAME=loopback

On all nodes in /etc/sysconfig/network, add the line

GATEWAYDEV=eth0

On all nodes, configure kernel parameters

net.ipv4.conf.ens192.arp_ignore = 1
net.ipv4.conf.ens192.arp_announce = 2
net.ipv4.ip_forward = 1

References

http://kb.linuxvirtualserver.org/wiki/Building_Two-Node_Directors/Real_Servers_using_LVS_and_Keepalived