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

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. For this to work the resource script for haproxy has to be downloaded too. Download on both nodes.

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
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

THIS HAS TO BE TESTED

#wget http://github.com/russki/cluster-agents/raw/master/haproxy
#echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf

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

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 19 as of 2018-01-20 13:35:20 → 
  Size: 3002
  Editor: Kristian Kallenberg
  Comment:
+   ← Revision 31 as of 2018-01-20 15:44:20 → ⇥
  Size: 3421
  Editor: Kristian Kallenberg
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
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-crypto_cipher: aes256
crypto_hash: sha512
+totem {
        crypto_cipher: aes256
        crypto_hash: sha512
}
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+Line 31:
-Generate the certificates. Note that this requires entropy, so use your system and the entropy will be generated.
+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.
-Line 34:
+Line 36:
-Add the local network and a multicast address to `/etc/corosync/corosync.conf` in the `interface` section
+==== Network ====
Add the local network and a multicast address to `/etc/corosync/corosync.conf` in the `interface` section.
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+Line 50:
-== Commmands ==
Run the following on startup
{{{#!highlight bash
# do not kill other node
+==== Nodes ====
Do not kill the other node.
{{{
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+Line 54:
-# disable quorum due to two nodes only
+}}}
Disable quorum due to two nodes only.
{{{
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-# configure shared IP
+}}}
Configure shared IP-address.
{{{
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-# create heartbeat for haproxy
+}}}
Create heartbeat for haproxy. For this to work the resource script for haproxy has to be downloaded too. Download on both nodes.
{{{
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
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+Line 68:
-# 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.
{{{
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-# relation between IP and haproxy servers
+}}}
Create the relation between IP-address and haproxy servers
{{{
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-# IP should be up before haproxy starts
crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance
+}}}
IP-address should be up before haproxy starts
{{{
crm configure order haproxyAfterIPs mandatory: haproxySharedIP haproxyLoadBalance
}}}
THIS HAS TO BE TESTED
{{{
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