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How to setup linux loadbalancer for windows real server using ldirectord-lvs-heartbeat

Posted January 27th, 2010 by gnulinux

Required operating system and packages

First of all install centos 5.2 with minimal packages and no gui required.
Packages required for setting up linux server as loadbalancer are as below.
heartbeat-2.1.4-4.1.i386.rpm
heartbeat-devel-2.1.4-4.1.i386.rpm
heartbeat-ldirectord-2.1.4-4.1.i386.rpm
heartbeat-pils-2.1.4-4.1.i386.rpm
heartbeat-stonith-2.1.4-4.1.i386.rpm
libnet-1.1.2.1-2.1.i386.rpm
perl-MailTools-1.76-1.el5.rf.noarch.rpm

There might me some more package dependencies but it can be resolved by installing those packages from cd.
ldirector.conf -- This is main configuration file for loadbalancer. Default location for this file is
/etc/ha.d/

    checktimeout=3
    checkinterval=5
    autoreload=yes
    logfile="/var/log/ldirectord.log"
    quiescent=yes
    #fork=yes

    virtual=10.10.10.214:80
    real=10.10.10.225:80 masq
    real=10.10.10.226:80 masq
    service=http
    request="index.html"
    receive="Still alive"
    scheduler=rr
    protocol=tcp
    checktype=connect
    # persistent = 10
    netmask = 255.255.255.255

Virtual IP on loadbalancer.

We need to configure one of the interface with virtual ip on loadbalancer. In this example we have setup eth0:0 with 10.10.10.214 which is a loadbalanced virtual ip for http traffic towards both real servers 10.10.10.225 & 10.10.10.226.

Important Notes:

  • Packet forwarding should be enabled as our load balancers will be acting as router. To enable packet forwarding edit /etc/sysctl.conf and change value for net.ipv4.ip_forward directive = 1.
  • Gateway of all real servers should be set to the virtual IP (Floating IP)

    • Steps to configure heartbeat for auto_failover

    Default directory which holds all configuration files is /etc/ha.d.
    important configuration files for heartbeat configuration is ha.cf, authkeys and haresources.

    authkeys : This file holds authentication key and it must be same on both servers. You can generate it on 1 server and then copy over to another server.
    To generate authkeys file use following command as root user.
    #( echo -ne "auth 1\n1 md5 "; dd if=/dev/urandom bs=512 count=1| openssl md5) > /etc/ha.d/authkeys

    ha.cf : It is an important configuration for heartbeat. It holds information about Interface in use for heartbeat, port number, real servers etc ..

      crm on
      udpport 696
      bcast eth0
      node lb01 lb02
      auto_failback on

    haresources :

    It is an important configuration for heartbeat. It holds information about fail over resources. e.g floating IP .
    lb01 IPaddr::10.10.10.214/25/eth0

    Important Note:

    To add another virtual IP (Load Balanced IP) we need to edit 2 configuration files.

  • /etc/ha.d/haresources : As mentioned earlier this file holds configuration for loadbalanced / Floating IP address. You can setup as many resources as you want in this conf file.
  • /etc/ha.d/ldirectord.cf : As mentioned earlier this file holds configuration for various required directive for actual load balancing service.

    • IPTables rules linux server. These rules are not mandatory. just for reference only.
    iptables -t mangle -A PREROUTING -p tcp -d 10.10.10.214 --dport 80 -j MARK --set-mark 80
    iptables -t nat -A POSTROUTING -p tcp -s 10.10.10.225 --sport 80 -j MASQUERADE
    iptables -t nat -A POSTROUTING -p tcp -s 10.10.10.226 --sport 80 -j MASQUERADE

    Important Note.

    On real server default gateway must be ip address of linux load balancer.

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