Implement a Cluster to Reduce Client Read Latency 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 log in 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

First copy the MySQL Watchdog script and Galera Load Balancer service files into place:

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

We will use the Source Tracking (--source) policy to ensure that connections always go to the same node, reducing client latency:

sudo vim /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"

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

Start the service:

sudo service glb start
sudo service glb status

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

Check GLB status to confirm:

sudo service glb status

Nodes in other regions can be added with a lower weight to provide failover capability:

sudo service glb add "10.0.1.110:3306:1"

We can then simulate a failure of node0 and test the connection:

sudo systemctl stop mariadb.service
mysql -h 10.0.1.100 -P 13306 -u remote -p