Introduction

This is a sample work to learn about docker, containers, running MySQL in docker and setting up MySQL replication using docker containers.

Directory structure explained

Here is the directory structure and its explanation

MySQLReplDocker
    |
    +--- conf/
    |       +--- master1.cnf
    |       +--- master2.cnf
    |       +--- slave1.cnf
    |       +--- slave2.cnf
    +--- data/
    |       +--- master1/
    |       +--- master2/
    |       +--- slave1/
    |       +--- slave2/
    +--- docker/
    |       +--- master-2-slave.yml
    |       +--- master-2-master.yml
    |       +--- slave-2-master-2-master-2-slave.yml
    +--- scripts/
    |       +--- common-functions.sh
    |       +--- master-2-slave.sh
    |       +--- master-2-master.sh
    |       +--- slave-2-master-2-master-2-slave.sh
    +--- start
    +--- stop
    +--- check_params.sh

• The folder "conf" contains the MySQL configuration for master and slave nodes.
• The folder "data" contains folders to hold data for master and slave nodes.
• The folder "docker" contains the docker container configuation files
• The folder "scripts" contains bash script which does the real job of setup of replication between the nodes

How to get MySQL containers up and running

To run a MySQL master-slave container replication execute the command

bash start master-slave

To run a MySQL master-master container replication execute the command

bash start master-master

To run a MySQL slave-master-master-slave replication execute the command

bash start slave-master-master-slave

Seeing replication in action

In order to see if the replication is actually working, you need to enable our nerd mode. Lets kick in. Execute the following command to see the docker containers which are currently running

bash info master-slave

This will list down the containers, where you can clearly identify the MySQL master(s) and slave(s) nodes. In order to connect to any of the container, you can execute

docker container exec -it <name-of-container> mysql -u root -p <mysql-password>

The name of the container is the first column from the output of info command. Once you are inside the prompt you can execute either of the following commands

SHOW MASTER STATUS

SHOW SLAVE STATUS\G

NOTE: Find the passwords in .env file

You can repeat the command for all the MySQL containers and then play around and see the replication action coming live.

In case you are not comfortable using command line for interacting with MySQL, this repo also has support for phpMyAdmin. You can access phpMyAdmin over the port 8080

Access http://localhost:8080 in your favorite browser

For hostname, username, and password refer to the .env file