Creating a Galera Cluster with LXD

45 minutes
  • 3 Learning Objectives

About this Hands-on Lab

LXD offers a quick-to-deploy, highly-efficient environment in which we can host a fault-resistant Galera cluster. In this hands-on lab, we’ll do just that by creating and configuring an initial container, then using that as a basis for a three-node Galera cluster.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Configure the Initial Cluster Containers

Create the container:

lxc launch ubuntu:18.04 galera01

Access the container and run initial updates:

lxc exec galera01 -- bash
apt update
apt upgrade

Add the MariaDB repository:

apt-key adv --recv-keys --keyserver hkp:// 0xF1656F24C74CD1D8
add-apt-repository 'deb [arch=amd64,ppc64el] bionic main'
apt update

Install MariaDB:

apt install mariadb-server -y

Run mysql_secure_installation:


Update the innodb_buffer_pool_size for the MariaDB configuration:

vim /etc/mysql/my.cnf
innodb_buffer_pool_size = 16M

Configure the firewall:

ufw enable
ufw allow 3306/tcp
ufw allow 4444/tcp
ufw allow 4567/tcp
ufw allow 4568/tcp
ufw allow 4567/udp
ufw status

Exit the container and take a snapshot:

lxc snapshot galera01 init

Create the two additional containers and start them:

lxc copy galera01/init galera02
lxc copy galera01/init galera03
lxc start galera02
lxc start galera03
Configure Galera

View all containers and make note of each IP address:

lxc list

Open the galera.cnf configuration in the cloud_user‘s home directory and update the wsrep_cluster_address to list all IP addresses. Update the wsrep_node_address and wsrep_node_name for the galera01 node:

vim galera.cnf

# Galera Provider Configuration
# Galera Cluster Configuration

# Galera Synchronization Configuration

# Galera Node Configuration

Push to the first container:

lxc file push galera.cnf galera01/etc/mysql/conf.d/galera.cnf

Update the configuration file again, changing the address and name so it works with galera02:

vim galera.cnf
lxc file push galera.cnf galera02/etc/mysql/conf.d/galera.cnf

Do the same for galera03:

vim galera.cnf
lxc file push galera.cnf galera03/etc/mysql/conf.d/galera.cnf
Start the Cluster

Stop MySQL on all nodes:

lxc exec galera01 -- systemctl stop mysql
lxc exec galera02 -- systemctl stop mysql
lxc exec galera03 -- systemctl stop mysql

Start the Galera cluster:

lxc exec galera01 -- galera_new_cluster
lxc exec galera02 -- systemctl start mysql
lxc exec galera03 -- systemctl start mysql

To confirm that everything is working, view the cluster size on all containers:

lxc exec galera01 -- mysql -u root -p -e "show status like 'wsrep_cluster_size'"
lxc exec galera02 -- mysql -u root -p -e "show status like 'wsrep_cluster_size'"
lxc exec galera03 -- mysql -u root -p -e "show status like 'wsrep_cluster_size'"

Additional Resources

You have been tasked with setting up an initial Galera cluster on an Ubuntu 18.04 container for use with a recently-containerized legacy application. Create and configure the initial Galera server, snapshot it, then create two additional containers and the configuration appropriately.

What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

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