Practitioner Level

Implement a Write Scalable Cluster Using MariaDB Galera Cluster and Galera Load Balancer

15 minutes

6 Learning Objectives

In this hands-on lab, you are working as a DBA and have been tasked with configuring a Write Scalable MariaDB Galera Cluster.

The cluster is already up and running, but you will need to install the Galera Load Balancer and configure it appropriately.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Set the root Database User’s Password and Create a Database User Account

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';

Install the Prerequisite Packages

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

Build the Binaries

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

Configure and Start Galera Load Balancer

We will start one node. More nodes can be added as necessary.
The least-connection policy is used by default to distribute connections across nodes:

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

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="10.0.1.100:3306:1"

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

sudo service glb start
sudo service glb status

Confirm Connection to Node

Create a new connection:

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

Confirm connection count in GLB:

sudo service glb status

Add Node and Confirm New Connections Are Routed Correctly

Add the node:

sudo service glb add "10.0.1.110:3306:1"

Confirm connection:

sudo service glb status

Additional Resources

In this hands-on lab you are working as a DBA and have been tasked with configuring a Write Scalable MariaDB Galera Cluster.
The cluster is already up and running, but you will need to install the Galera Load Balancer and configure it appropriately.
To do this, you will need to complete the following steps on either of the nodes:

Set root database user's password and create a database user account.
Install the prerequisite packages.
Build the Galera Load Balancer binaries.
Configure and start Galera Load Balancer.
Confirm the connection to the node.
Add the node and confirm new connections are routed correctly.

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