Incomplete, do not use!

Corosync and HA-proxy

We will use corosync to create a virtual IP-address which is shared by two systems. One of the systems has the virtual IP-address. If the system goes down, the other system will take over the virtual IP-address. HA-proxy will be running on each of the hosts relaying incoming HTTP-requests to two webservers.

• 192.168.1.47 www (virtual IP-address)
• 192.168.1.48 haproxy01
• 192.168.1.49 haproxy02

Software

apt-get install corosync haproxy crmsh

Configuration

Before binding to the DNS name www make sure the DNS server knows that name. There is no physical or virtual network interfaces, so the DNS updates has to be done manually.

HA-proxy

Add the following to /etc/haproxy/haproxy.cfg

listen webfarm 
        bind www:80
        mode http
        balance roundrobin
        cookie LBN insert indirect nocache
        option httpclose
        option forwardfor
        server haproxy01 www01:80 cookie node1 check
        server haproxy02 www02:80 cookie node2 check

Restart HA-proxy

service haproxy restart

Corosync

Add the local network and a multicast address to /etc/corosync/corosync.conf in the interface section

interface {
        bindnetaddr: 192.168.1.0 
        mcastaddr: 239.192.1.1
}

Restart corosync to load the new configuration.

service corosync restart

Commmands

Run the following on startup

   1 # do not kill other node
   2 crm configure property stonith-enabled=false
   3 # disable quorum due to two nodes only
   4 crm configure property no-quorum-policy=ignore
   5 # configure shared IP
   6 crm configure primitive haproxySharedIP  ocf:heartbeat:IPaddr2 params ip=192.168.1.47 cidr_netmask=24 op monitor interval=5s
   7 # create heartbeat for haproxy
   8 crm configure primitive haproxyLoadBalance ocf:heartbeat:haproxy params conffile=/etc/haproxy/haproxy.cfg op monitor interval=10s
   9 
  10 # make sure the same server has both IP and service
  11 #crm configure group haproxyIPs haproxySharedIP meta ordered=false
  12 crm configure group haproxy haproxySharedIP haproxyLoadBalance
  13 # relation between IP and haproxy servers
  14 crm configure colocation haproxyWithIPs INFINITY: haproxyLoadBalance haproxySharedIP
  15 # IP should be up before haproxy starts
  16 crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance 
  17 #wget http://github.com/russki/cluster-agents/raw/master/haproxy
  18 #echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf
  19 

References

• https://wiki.debian.org/Debian-HA/ClustersFromScratch