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

4 hours
  • 6 Learning Objectives

About this Hands-on Lab

In this activity, you are working as a DBA and have been tasked with configuring a MariaDB Galera Cluster in a Primary-Replica configuration. 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 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';
Install the Prerequisite Packages
sudo yum -y install git autoconf automake libtool gcc-c++ nmap-ncat
Build the Galera Load Balancer Binaries
git clone https://github.com/codership/glb
cd glb
./bootstrap.sh
./configure
make
sudo make install
Configure and Start Galera Load Balancer
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
Confirm Connections to Primary and Replica Nodes

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
Promote Replica to Primary

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

Additional Resources

In this activity, you are working as a DBA and have been tasked with configuring a MariaDB Galera Cluster in a Primary-Replica configuration. 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:

  1. Set the root database user's password and create a database user account.
  2. Install the prerequisite packages.
  3. Build the Galera Load Balancer binaries.
  4. Configure and start Galera Load Balancer.
  5. Confirm connections to Primary and Replica nodes.
  6. Promote Replica to Primary.

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