Keepalived

Keepalived Loadbalancer

Introduction

this page contains a basic description about how to set up keepalived for Open-Xchange cluster. This example is to work on debian systems. Keepalived mode is Direct Routing.

It is required to have ox servers and loadbalancer connected to the same switch or hub and that there is no filter for network packages between (some virtualization system do filter, too), so that MAC rewriting works.

For more information please see: www.keepalived.org

Software installation

Packages are installed using

test1:~# apt-get install keepalived 

Keepalived requires some kernel modules to be loaded. They are loaded by the ipvsadmm service. So we enable it using dpkg-reconfigure:

dpkg-reconfigure ipvsadm

Answer the questions with "Yes" ("load ... at boot") and then "backup" for "Daemon method".

Configuration example: HTTP

Create a file

/etc/keepalived/keepalived.conf

with following contend (adapt network adresses)

global_defs {
    router_id OX
}

vrrp_sync_group OX_GROUP {
    group {
        OX_GOUP
    }
}

vrrp_instance OX_VRRP {
    state BACKUP
    interface eth0
    garp_master_delay 10
    virtual_router_id 10
    priority 101
    nopreempt
    advert_int 1
    authentication {
        auth_type AH   # Simple 'PASS' can use
        auth_pass 1234 # example password '1234' 
    }
    virtual_ipaddress {
        10.20.30.77/24 brd 10.20.30.255 dev eth0 # virtual service ip 10.20.30.67
    }
    virtual_ipaddress_excluded {
    }
}

virtual_server_group OX_HTTP {
        10.20.30.77 80         # virtual ip and port 80
}

virtual_server_group OX_OL_PUSH {
        10.20.30.77 44335      # VIP VPORT
}

virtual_server group OX_HTTP {
    delay_loop 3
    lvs_sched  rr
    lvs_method DR
    protocol   TCP
    virtualhost 10.20.30.77

    real_server 10.20.30.123 80 {
        weight 1
        inhibit_on_failure
        HTTP_GET {
            url {
                path /servlet/TestServlet
                status_code 200
            } 
            connect_port 80
            connect_timeout 10
        }
    }

    real_server 10.20.30.321 80 {
        weight 1
        inhibit_on_failure
        HTTP_GET {
            url {
                path /servlet/TestServlet
                status_code 200
            }
            connect_port 80
            connect_timeout 10
        }
    } 
}

virtual_server group OX_OL_PUSH {
    delay_loop 3
    lvs_sched  rr
    lvs_method DR
    protocol   UDP

    real_server 10.20.30.123 44335 {
        weight 1
        inhibit_on_failure
	  TCP_CHECK {
                 connect_port 9999
		  connect_timeout 5
        }
    }

    real_server 10.20.30.321 44335 {
        weight 1
        inhibit_on_failure
        TCP_CHECK {
                 connect_port 9999
		  connect_timeout 5
        }
    }
}

Configuration example: Keepalived for Galera Loadbalancing

Here:

• loadbalancer IP 10.20.29.174
• Three galera nodes: 10.20.29.140, 10.20.29.142, 10.20.29.138

For the configuration: adjust the router_id, virtual_router_id, and authentication information.

global_defs {
  # This should be unique.
  router_id galera-lb
}

vrrp_instance mysql_pool {
  # The interface we listen on.
  interface eth0

  # The default state, one should be master, the others should be set to SLAVE.
  state MASTER

  # This should be the same on all participating load balancers.
  virtual_router_id 19

  priority 101

  # Set the interface whose status to track to trigger a failover.                   
  track_interface {           
    eth0
  }

  # Password for the loadbalancers to share.
  authentication {
    auth_type PASS
    auth_pass Twagipmiv3
  }

  # This is the IP address that floats between the loadbalancers.
  virtual_ipaddress {
   10.20.29.174 dev eth0
  }
}

# Here we add the virtal mysql node
virtual_server 10.20.29.174 3306 {
  delay_loop 6
  # Round robin, but you can use whatever fits your needs.
  lb_algo rr
  lb_kind DR
  protocol TCP

  # For each server add the following. 
  real_server 10.20.29.140 3306 {
    weight 10
    MISC_CHECK {
      misc_path "/etc/keepalived/galera-checker.pl 10.20.29.140"
      misc_timeout 5
    }
  }
  real_server 10.20.29.142 3306 {
    weight 11
    MISC_CHECK {
      misc_path "/etc/keepalived/galera-checker.pl 10.20.29.142"
      misc_timeout 5
    }
  }
  real_server 10.20.29.138 3306 {
    weight 12
    MISC_CHECK {
      misc_path "/etc/keepalived/galera-checker.pl 10.20.29.138"
      misc_timeout 5
    }
  }
}

Networking adjustments

The following instructions are valid for debian.

1. For the keepalived node, configure in /etc/sysctl.conf: net.ipv4.ip_forward = 1
2. For the server nodes, use a stanza in the /etc/network/interfaces file. Adjust the IP.

auto lo:0
iface lo:0 inet static
    address 10.20.30.77
    netmask 255.255.255.255
    pre-up echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
    pre-up echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
    post-up /sbin/route add -host 10.20.30.77 dev lo:0
    pre-down /sbin/route del -host 10.20.30.77 dev lo:0
    # reset to defaults
    post-down echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
    post-down echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce

The effect of those settings should be self-explanatory. How to do this on other operating systems needs to be documented here.