Implement a Primary-Replica Cluster Using MariaDB Galera Cluster and Galera Load Balancer

The database nodes are running and connected to the cluster, however the root user's password has not been set. You must first set the root user's password by running the mysql_secure_installation script:

sudo mysql_secure_installation

Now you can connect to the database as the root user and create a user account:

mysql -u root -p

Once connected, you can use the following SQL to create a user named remote who is able to login remotely. Be sure to replace mypasswd with a password of your choice.

create user remote identified by 'mypasswd';
grant usage on *.* to 'remote'@'%' identified by 'mypasswd';

sudo yum -y install git autoconf automake libtool gcc-c++ nmap-ncat

git clone https://github.com/codership/glb
cd glb
./bootstrap.sh
./configure
make
sudo make install

sudo cp /home/cloud_user/glb/files/mysql.sh /usr/local/bin/mysql-check.sh
sudo cp /home/cloud_user/glb/files/glbd.sh /etc/init.d/glb

Create glbd configuration file:

sudo vi /etc/sysconfig/glbd

# Address to listen for client connections at. Mandatory parameter.
# To bind to all interfaces only port should be specified.
LISTEN_ADDR="10.0.1.100:13306"

# Address for controlling connection. Mandatory part is port.
# If not specified control socket will not be opened
CONTROL_ADDR="127.0.0.1:4444"

# Target servers for client connections, space separated.
# Target specification: IP[:PORT[:WEIGHT]] (WEIGHT and PORT optional)
# WEIGHT defaults to 1, PORT defaults to LISTEN_ADDR port.
DEFAULT_TARGETS="10.0.1.100:3306:10 10.0.1.110:3306:1"

# Other glbd options if any as they would appear on the command line.
OTHER_OPTIONS="--single --watchdog exec:'/usr/local/bin/mysql-check.sh -uremote -pmypasswd'"

Start the service:

sudo service glb start
sudo service glb status

Connect to the primary node via the load balancer:

mysql -h 10.0.1.100 -P 13306 -u remote -p

The connection is sent to the single server with the highest weight of those available, in this case node0.

Connections to the replica can be made directly on port 3306:

mysql -h 10.0.1.110 -P 3306 -u remote -p

A replica node can become the primary node by changing each of their weights:

service glb add 10.0.1.100:3306:1
service glb add 10.0.1.110:3306:10

Confirm connections are routed to node1:

mysql -h 10.0.1.100 -P 13306 -u remote -p
service glb status