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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. | 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 requests. |
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| listen webfarm | listen www_farm |
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| server haproxy01 www01:80 cookie node1 check server haproxy02 www02:80 cookie node2 check |
server www01 www01:80 cookie node1 check server www02 www02:80 cookie node2 check listen galera_cluster bind mariadb:3306 mode tcp balance roundrobin option tcpka option mysql-check user haproxy server mariadb01 mariadb01:3306 check weight 1 server mariadb02 mariadb02:3306 check weight 1 server mariadb03 mariadb03:3306 check weight 1 |
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| === Apache === | |
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| }}} === Mariadb === {{{ while true; do mysql -u haproxy -p -h mariadb -e "select @@hostname"; sleep 1; done |
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| * https://www.howtoforge.com/tutorial/how-to-setup-haproxy-as-load-balancer-for-mariadb-on-centos-7/#b-install-mariadb-galera-server * https://www.digitalocean.com/community/tutorials/how-to-use-haproxy-to-set-up-mysql-load-balancing--3 |
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 requests.
- 192.168.1.49 haproxy01
- 192.168.1.50 haproxy02
- 192.168.1.51 www (virtual IP-address)
- 192.168.1.54 mariadb (virtual IP)
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
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
As we will let corosync start haproxy, we will have to disable haproxy as a service.
service haproxy stop systemctl disable haproxy
Webfarm
Add the following to /etc/haproxy/haproxy.cfg
listen www_farm
bind www:80
mode http
balance roundrobin
cookie LBN insert indirect nocache
option httpclose
option forwardfor
server www01 www01:80 cookie node1 check
server www02 www02:80 cookie node2 check
listen galera_cluster
bind mariadb:3306
mode tcp
balance roundrobin
option tcpka
option mysql-check user haproxy
server mariadb01 mariadb01:3306 check weight 1
server mariadb02 mariadb02:3306 check weight 1
server mariadb03 mariadb03:3306 check weight 1Copy the configuration /etc/haproxy/haproxy.cfg to the other host.
Corosync
Encryption
Edit /etc/corosync/corosync.conf and make the following changes.
totem {
cluster_name: www
crypto_cipher: aes256
crypto_hash: sha512
}
Authentication Key
Generate the authkey. 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 or install haveged.
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
}Copy the configuration /etc/corosync/corosync.conf and the authkey /etc/corosync/authkey to the other host.
Restart corosync on both hosts to load the new configuration.
service corosync restart
The two nodes should now be configured to see each other. Run crm status to check.
Stack: corosync Current DC: haproxy01 (version 1.1.16-94ff4df) - partition with quorum Last updated: Sat Feb 1 14:41:09 2020 Last change: Sat Feb 1 14:40:51 2020 by hacluster via crmd on haproxy01 2 nodes configured 0 resources configured Online: [ haproxy01 haproxy02 ] No resources
Nodes
Do not kill the other node. This is needed as inactive nodes normally should be killed. It can be change later on, once fencing has been configured.
crm configure property stonith-enabled=false
Disable quorum due to two nodes only. This will make sure that the cluster keeps running if only one node is up.
crm configure property no-quorum-policy=ignore
Configure shared IP-address. This is the virtual IP-address.
crm configure primitive wwwSharedIP ocf:heartbeat:IPaddr2 params ip=192.168.1.51 cidr_netmask=24 op monitor interval=5s
Create heartbeat for haproxy.
crm configure primitive wwwLoadBalance 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 www wwwSharedIP wwwLoadBalance
IP-address should be up before haproxy starts.
crm configure order haproxyAfterIP mandatory: wwwSharedIP wwwLoadBalance
Test it
Apache
while true; do wget --quiet http://www/ -O /dev/stdout; sleep 1; done
Mariadb
while true; do mysql -u haproxy -p -h mariadb -e "select @@hostname"; sleep 1; done