how to setup mariadb galera cluster in docker container

 1. create network (one time)

   docker network create --subnet=172.18.0.0/16 mynet123

2. create image that can start service in container (one time)

   mkdir systemd

   cd systemd

   vim Dockerfile

   FROM almalinux

   ENV container docker

   RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in ; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done);

   RUN rm -rf /lib/systemd/system/multi-user.target.wants/ \

   && rm -rf /etc/systemd/system/.wants/ \

   && rm -rf /lib/systemd/system/local-fs.target.wants/ \

   && rm -f /lib/systemd/system/sockets.target.wants/udev \

   && rm -f /lib/systemd/system/sockets.target.wants/initctl \

   && rm -rf /lib/systemd/system/basic.target.wants/ \

   && rm -f /lib/systemd/system/anaconda.target.wants/*

   VOLUME [ “/sys/fs/cgroup” ]

   CMD ["/usr/sbin/init"]

3. build image (one time)

   docker build -t almalinux-md .

4. start the container in the background

   docker run -v /tmp/node1/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip 172.18.0.11 --name node1  almalinux-md 

   docker run -v /tmp/node2/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip 172.18.0.12 --name node2  almalinux-md

   docker run -v /tmp/node3/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip 172.18.0.13 --name node3  almalinux-md  

5. attach it and so can install mariadb and gelera, etc

   docker exec -it node1 bash

   docker exec -it node2 bash

   docker exec -it node3 bash

6. install in all 3 nodes

   dnf install -y mariadb-server.x86_64  mariadb.x86_64 rsync python3-policycoreutils vim nc telnet epel-release.noarch mariadb-server-galera.x86_64

7. on first node

   systemctl start mariadb

   systemctl status mariadb

   [root@6c3d7f5bc394 /]# mysql -uroot

   MariaDB [(none)]> set password = password("password");

   quit;

   systemctl stop mariadb

      

8. from step 5. wsrep_node_address and wsrep_node_name update to its corresponding name   

   [root@cfeee129fe92 /]# cat /etc/my.cnf.d/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/lib64/galera/libgalera_smm.so

   # Galera Cluster Configuration

   wsrep_cluster_name="ot_mariadb_cluster"

   wsrep_cluster_address="gcomm://172.18.0.11,172.18.0.12,172.18.0.13"

   # Galera Synchronization Configuration

   wsrep_sst_method=rsync

   # Galera Node Configuration

   wsrep_node_address="172.18.0.13"

   wsrep_node_name="node3"

   [root@cfeee129fe92 /]# 

9.  on first node, start the cluster

    galera_new_cluster

   

10. check on the first node,

    mysql -u root -ppassword -e "SHOW STATUS LIKE 'wsrep_cluster_size'"   

   

11. bring up the remaining nodes one by one

    systemctl start mariadb

    mysql -u root -ppassword -e "SHOW STATUS LIKE 'wsrep_cluster_size'"   

12. ready to write/read

mysql -u root -ppassword -e 'CREATE DATABASE playground;

CREATE TABLE playground.equipment ( id INT NOT NULL AUTO_INCREMENT, type VARCHAR(50), quant INT, color VARCHAR(25), PRIMARY KEY(id));

INSERT INTO playground.equipment (type, quant, color) VALUES ("slide", 2, "blue");'

mysql -u root -ppassword -e 'SELECT * FROM playground.equipment;'