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

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

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

-  ⇤ ← Revision 27 as of 2018-01-20 15:28:21 → 
  Size: 3126
  Editor: Kristian Kallenberg
  Comment:
+   ← Revision 33 as of 2018-01-20 16:08:18 → ⇥
  Size: 3422
  Editor: Kristian Kallenberg
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 50:
+==== 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
}}}
-Line 51:
+Line 58:
-THIS WORKS
-Line 56:
+Line 62:
-THIS HAS TO BE TESTED
+Disable quorum due to two nodes only.
-Line 59:
+Line 64:
-# disable quorum due to two nodes only
-Line 61:
+Line 65:
-# configure shared IP
+}}}
Configure shared IP-address.
{{{
-Line 63:
+Line 69:
-# create heartbeat for haproxy
+}}}
Create heartbeat for haproxy.
{{{
-Line 65:
+Line 73:
-# make sure the same server has both IP and service
#crm configure group haproxyIPs haproxySharedIP meta ordered=false
+}}}
Make sure the same server has both IP and service at the same time.
{{{
-Line 69:
+Line 77:
-# relation between IP and haproxy servers
+}}}
Create the relation between IP-address and haproxy servers.
{{{
-Line 71:
+Line 81:
-# IP should be up before haproxy starts
crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance 
#wget http://github.com/russki/cluster-agents/raw/master/haproxy
#echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf
-Line 77:
+Line 82:
+IP-address should be up before haproxy starts.
{{{
crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance
}}}
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+Line 106:
+== Test it ==
{{{
while true; do wget --quiet http://www/ -O /dev/stdout; sleep 1; done
}}}
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+Line 112:
-  * https://wiki.debian.org/Debian-HA/ClustersFromScratch
+ * https://wiki.debian.org/Debian-HA/ClustersFromScratch