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This page describes how to install and configure HAProxy and Keepalived to get a virtual IP working with a Galera cluster (datanode/services nodes) and Emmett cluster (monitoring nodes) that are already running.

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1. Edit /etc/my.cnf.d/server.cnf

2. Add the following:

   Code Block
   [mysqld] port=3307

3. Restart the service with service mariadb restart.
   To quickly check that MySQL is listening on the right port, you can use this command:

   Code Block
   netstat -tunap | grep mysql

Create an

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HAproxy user for each node

In MySQL, create an haproxy HAproxy user for each node. You can create the users on one of the clusters and they will replicate on the other nodes.

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You don’t need to give these users any privileges, haproxy HAproxy will just use them to check the connection.

Install and configure

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HAproxy

Do the following installation and configuration steps on each services node.

1. Use the following command to install haproxyHAproxy:

   Code Block
   yum install haproxy -y

2. Go to the following folder

   Code Block
   cd /etc/haproxy/

3. Copy the default configuration file

   Code Block
   mv haproxy.cfg haproxy.cfg.bak

4. Create a new configuration file called haproxy.cfg

5. Add the following configuration and save the file
   

   Code Block

   #--------------------------------------------------------------------- # Global settings #--------------------------------------------------------------------- global     # to have these messages end up in /var/log/haproxy.log you will     # need to:     #     # 1) configure syslog to accept network log events.  This is done     #    by adding the '-r' option to the SYSLOGD_OPTIONS in     #    /etc/sysconfig/syslog     #     # 2) configure local2 events to go to the /var/log/haproxy.log     #   file. A line like the following can be added to     #   /etc/sysconfig/syslog     #     #    local2.*                       /var/log/haproxy.log     #     log         127.0.0.1 local2     chroot      /var/lib/haproxy     pidfile     /var/run/haproxy.pid     maxconn     4000     user        haproxy     group       haproxy     daemon     # turn on stats unix socket     stats socket /var/lib/haproxy/stats.sock mode 600 level admin     stats timeout 2m #--------------------------------------------------------------------- # common defaults that all the 'listen' and 'backend' sections will # use if not designated in their block #--------------------------------------------------------------------- defaults     mode                    tcp     log                     global     option                  httplog     option                  dontlognull     option                  redispatch     retries                 3     timeout queue           1m     timeout connect         10s     timeout client          1m     timeout server          1m     timeout check           10s     maxconn                 3000 listen haproxy-monitoring *:8090   mode    http   stats   enable   stats   show-legends   stats   refresh           5s   stats   uri               /   stats   realm             Haproxy\ Statistics   stats   auth              monitor:AdMiN123   stats   admin             if TRUE #--------------------------------------------------------------------- # frontend galera-cluster #--------------------------------------------------------------------- frontend haproxy-galera-1     bind             *:3306     default_backend  galera-cluster #--------------------------------------------------------------------- # round robin balancing galera-cluster backend #--------------------------------------------------------------------- backend galera-cluster     balance     roundrobin     server  NodeServices1 ip1.example.com:3307 check     server  NodeServices2 ip2.example.com:3306 check     server  NodeServices3 ip3.example.com:3306 check

   Here you can see that haproxy is listening on port 3306, which was previously used by MySQL and it uses a round robin algorithm to balance the three nodes.
   
   You must add the IP of the node that you are configuring, as well as the rest of the nodes, and for the port, when you are configuring a node, you need to add the local MySQL port, which is 3307, and for the other nodes, the haproxy port, which is 3306.
   

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chkconfig haproxy on
service haproxy start

Check

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HAproxy

One way to check that haproxy HAproxy is running properly is to check a socket that the service creates on startup. To check the socket, we recommend the use of socat.

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Check that the command returns something different each time, which shows that it is balancing properly.

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Install and configure

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Keepalived

Do the following installation and configuration steps on each services node:

1. Install keepalivedKeepalived:

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   yum install keepalived -y

2. Go to the configuration folder

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   cd /etc/keepalived/

3. Copy the default configuration file

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   mv keepalived.conf keepalived.conf.bak

4. Create a new configuration file

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   vim keepalived.conf

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On the main node of the Galera cluster, add the following configuration for the main node for keepalivedKeepalived:

global_defs {
        router_id LBL01
}
vrrp_sync_group SyncGroup01 {
        group {
                FloatIP1
        }
}
vrrp_script check_haproxy {
        script "killall -0 haproxy"
        interval 2
        weight 2
}
vrrp_instance FloatIP1 {
        state MASTER
        interface eth0
        virtual_router_id 10
        priority 101
        advert_int 1
        virtual_ipaddress {

                vip.example.com

        }
        track_script {
                check_haproxy
        }
}

Here you need to specify the virtual IP, which in my the example configuration is 10.10.203.220. Also, keepalived Keepalived works with a main/secondary configuration, and this is the main configuration.

Add this the main configuration to the main node of the galera cluster, so it is also the main node for keepalivedKeepalived.

Then on each of the secondary nodes, make the following changes:

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As you can see, this is very similar to the command to check that haproxy HAproxy is working, but this time we are connecting to the virtual IP, which is supplied by keepalivedKeepalived, to check keepalivedKeepalived.

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Changes to API/UI

To make the Abiquo API use the virtual IP, log in to the server and do the following steps:

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1. Install haproxy with yum install haproxy -y

2. Backup default haproxy configuration file with:
   mv /etc/haproxy/haproxy.cfg /etc/haproxy/backup_haproxy.cfg

3. Create a new configuration file with: touch /etc/haproxy/haproxy.cfg

4. Edit the file and paste in the following configuration

5. Change the IP addresses in backend monitoring-cluster section to your monitoring nodes:

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   #--------------------------------------------------------------------- # Global settings #--------------------------------------------------------------------- global # to have these messages end up in /var/log/haproxy.log you will # need to: # # 1) configure syslog to accept network log events. This is done # by adding the '-r' option to the SYSLOGD_OPTIONS in # /etc/sysconfig/syslog # # 2) configure local2 events to go to the /var/log/haproxy.log # file. A line like the following can be added to # /etc/sysconfig/syslog # # local2.* /var/log/haproxy.log # log 127.0.0.1 local2 chroot /var/lib/haproxy pidfile /var/run/haproxy.pid maxconn 4000 user haproxy group haproxy daemon # turn on stats unix socket stats socket /var/lib/haproxy/stats.sock mode 600 level admin stats timeout 2m #--------------------------------------------------------------------- # common defaults that all the 'listen' and 'backend' sections will # use if not designated in their block #--------------------------------------------------------------------- defaults mode tcp log global option httplog option dontlognull option redispatch retries 3 timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout check 10s maxconn 3000 listen haproxy-monitoring *:8090 mode http stats enable stats show-legends stats refresh 5s stats uri / stats realm Haproxy\ Statistics stats auth monitor:AdMiN123 stats admin if TRUE #--------------------------------------------------------------------- # frontend monitoring-cluster #--------------------------------------------------------------------- frontend haproxy-monitoring-1 bind *:36639 default_backend monitoring-cluster #--------------------------------------------------------------------- # round robin balancing monitoring-cluster backend #--------------------------------------------------------------------- backend monitoring-cluster balance roundrobin server MonNode1 10.10.51.21:36638 check server MonNode2 10.10.51.22:36638 check

6. In the above configuration, haproxy is listening port to 36639 (bind), so open the firewall on this port with firewall-cmd --zone=public --permanent --add-port=36639/tcp and reboot the firewall service with: systemctl restart firewalld

7. When you have configured all of the above on all nodes, activate and start the service with:
   systemctl enable haproxy and systemctl start haproxy

8. To check if haproxy HAproxy is running, use socket.

   1. Install it with yum install socat -y

   2. Run the following in the terminal (copy all 3 lines and paste them at the same time):

      Code Block
      socat /var/lib/haproxy/stats.sock readline prompt show stat

   3. The output should be similar to the following
      There are two nodes and their status is up.

      

9. Install keepalived Keepalived with: yum install keepalived -y

10. Back up the configuration file with: mv /etc/keepalived/keepalived.conf /etc/keepalived/backup_keepalived.conf

11. Create a new configuration file with: touch /etc/keepalived/keepalived.conf

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