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Creating a Galera Cluster with LXD

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.

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Lab platform
Lab Info
Level
Intermediate
Last updated
Aug 09, 2025
Duration
45m

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Table of Contents
  1. Challenge

    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://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
    add-apt-repository 'deb [arch=amd64,ppc64el] http://ftp.utexas.edu/mariadb/repo/10.1/ubuntu bionic main'
    apt update
    

    Install MariaDB:

    apt install mariadb-server -y
    

    Run mysql_secure_installation:

    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:

    exit
    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
    
  2. Challenge

    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
    
    [mysqld]
    binlog_format=ROW
    default-storage-engine=innodb
    innodb_autoinc_lock_mode=2
    bind-address=0.0.0.0
    
    # Galera Provider Configuration
    wsrep_on=ON
    wsrep_provider=/usr/lib/galera/libgalera_smm.so
    # Galera Cluster Configuration
    wsrep_cluster_name="galera_cluster"
    wsrep_cluster_address="gcomm://<IP_ADDRESS>,<IP_ADDRESS>,<IP_ADDRESS>"
    
    # Galera Synchronization Configuration
    wsrep_sst_method=rsync
    
    # Galera Node Configuration
    wsrep_node_address="<IP_ADDRESS>"
    wsrep_node_name="galera01"
    

    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
    
    wsrep_node_address="<IP_ADDRESS>"
    wsrep_node_name="galera02"
    
    lxc file push galera.cnf galera02/etc/mysql/conf.d/galera.cnf
    

    Do the same for galera03:

    vim galera.cnf
    
    wsrep_node_address="<IP_ADDRESS>"
    wsrep_node_name="galera03"
    
    lxc file push galera.cnf galera03/etc/mysql/conf.d/galera.cnf
    
  3. Challenge

    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'"
    
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