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= Corosync =
We will use corosync to create a virtual IP which is share by two systems		 = Corosync and HA-proxy =
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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 ==
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apt-get install corosync apt-get install corosync haproxy crmsh
Line 7: Line 13:

== 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|DNS updates]] has to be done manually.

=== Corosync ===

==== Encryption ====
Edit `/etc/corosync/corosync.conf` and make the following changes.
{{{
totem {
        crypto_cipher: aes256
        crypto_hash: sha512
}
}}}

==== Certificates ====
Generate the certificates. Note that this requires entropy, so use your system and the entropy will be generated. Speed this up by running `dd if=/dev/vda of=/dev/null` in another terminal.
{{{
corosync-keygen
}}}

==== Network ====
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
}}}

==== HA-proxy resource script ====
Download the HA-proxy resource script, place it in `/usr/lib/ocf/resource.d/heartbeat/haproxy` and make it executeable.
{{{
wget https://raw.githubusercontent.com/thisismitch/cluster-agents/master/haproxy -O /usr/lib/ocf/resource.d/heartbeat/haproxy
chmod +x /usr/lib/ocf/resource.d/heartbeat/haproxy
}}}

==== Nodes ====
Do not kill the other node.
{{{
crm configure property stonith-enabled=false
}}}
Disable quorum due to two nodes only.
{{{
crm configure property no-quorum-policy=ignore
}}}
Configure shared IP-address.
{{{
crm configure primitive haproxySharedIP ocf:heartbeat:IPaddr2 params ip=192.168.1.47 cidr_netmask=24 op monitor interval=5s
}}}
Create heartbeat for haproxy.
{{{
crm configure primitive haproxyLoadBalance ocf:heartbeat:haproxy params conffile=/etc/haproxy/haproxy.cfg op monitor interval=10s
}}}
Make sure the same server has both IP and service at the same time.
{{{
crm configure group haproxy haproxySharedIP haproxyLoadBalance
}}}
Create the relation between IP-address and haproxy servers.
{{{
crm configure colocation haproxyWithIPs INFINITY: haproxyLoadBalance haproxySharedIP
}}}
IP-address should be up before haproxy starts.
{{{
crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance
}}}

=== 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
}}}

== Test it ==
{{{
while true; do wget --quiet http://www/ -O /dev/stdout; sleep 1; done
}}}

== References ==
 * https://wiki.debian.org/Debian-HA/ClustersFromScratch

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.

Corosync

Encryption

Edit /etc/corosync/corosync.conf and make the following changes. 

totem {
        crypto_cipher: aes256
        crypto_hash: sha512
}

Certificates

Generate the certificates. Note that this requires entropy, so use your system and the entropy will be generated. Speed this up by running dd if=/dev/vda of=/dev/null in another terminal. 

corosync-keygen

Network

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

HA-proxy resource script

Download the HA-proxy resource script, place it in /usr/lib/ocf/resource.d/heartbeat/haproxy and make it executeable. 

wget https://raw.githubusercontent.com/thisismitch/cluster-agents/master/haproxy -O /usr/lib/ocf/resource.d/heartbeat/haproxy
chmod +x /usr/lib/ocf/resource.d/heartbeat/haproxy

Nodes

Do not kill the other node. 

crm configure property stonith-enabled=false

Disable quorum due to two nodes only. 

crm configure property no-quorum-policy=ignore

Configure shared IP-address. 

crm configure primitive haproxySharedIP  ocf:heartbeat:IPaddr2 params ip=192.168.1.47 cidr_netmask=24 op monitor interval=5s

Create heartbeat for haproxy. 

crm configure primitive haproxyLoadBalance ocf:heartbeat:haproxy params conffile=/etc/haproxy/haproxy.cfg op monitor interval=10s

Make sure the same server has both IP and service at the same time. 

crm configure group haproxy haproxySharedIP haproxyLoadBalance

Create the relation between IP-address and haproxy servers. 

crm configure colocation haproxyWithIPs INFINITY: haproxyLoadBalance haproxySharedIP

IP-address should be up before haproxy starts. 

crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance

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

Test it

while true; do wget --quiet http://www/ -O /dev/stdout; sleep 1; done

References

None: Corosync and HA-proxy (last edited 2021-08-12 09:31:08 by Kristian Kallenberg)