Creating a Galera Cluster with LXD

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

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

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'"