How to build a highly available MySQL container cluster on Linux?

How to build a highly available MySQL container cluster on Linux?

With the rise of cloud computing and container technology, more and more enterprises are beginning to use containers to build applications. As one of the most commonly used relational databases, MySQL can also achieve high availability through containerization. In this article, we will introduce how to build a highly available MySQL container cluster on Linux and provide relevant code examples.

Step 1: Prepare the environment

First, you need a Linux host to build a MySQL container cluster. Make sure Docker and Docker Compose are installed on this host. If it is not installed, you can install it with the following command:

$ sudo apt-get update
$ sudo apt-get install docker.io
$ sudo apt-get install docker-compose

Step 2: Create a Docker image

Next, you need to create a MySQL image to run the container. The image building process can be defined through Dockerfile. Create a file named Dockerfile and add the following content in it:

FROM mysql:8.0

ENV MYSQL_ROOT_PASSWORD your_password
ENV MYSQL_DATABASE your_database

COPY your_script.sql /docker-entrypoint-initdb.d/

In the above code, your_password is the root user password of MySQL, your_database is the name of the database to be created, and your_script.sql is the initialization script file to be executed. These parameters can be modified according to actual conditions.

After saving and exiting the file, use the following command to build the image:

$ sudo docker build -t your_image_name .

where your_image_name is the name you gave the image.

Step 3: Create a Docker Compose file

Before building a MySQL container cluster, you need to create a docker-compose.yml file to define the containers in the cluster. Create a file called docker-compose.yml and add the following content in it:

version: '3'

services:
  mysql1:
    image: your_image_name
    restart: always
    ports:
      - 3306:3306
    volumes:
      - ./mysql1:/var/lib/mysql
    environment:
      - MYSQL_REPLICATION_MODE=master
      - MYSQL_REPLICATION_USER=repl_user
      - MYSQL_REPLICATION_PASSWORD=repl_password

  mysql2:
    image: your_image_name
    restart: always
    volumes:
      - ./mysql2:/var/lib/mysql
    environment:
      - MYSQL_REPLICATION_MODE=slave
      - MYSQL_MASTER_HOST=mysql1
      - MYSQL_MASTER_PORT=3306
      - MYSQL_MASTER_USER=repl_user
      - MYSQL_MASTER_PASSWORD=repl_password

In the above code, your_image_name is the MySQL image built earlier name. mysql1 and mysql2 represent the names of two MySQL containers respectively. The MYSQL_REPLICATION_MODE parameter sets the replication mode of the container, master represents the master node, and slave represents the slave node. MYSQL_REPLICATION_USER and MYSQL_REPLICATION_PASSWORD are the username and password of the replication user. MYSQL_MASTER_HOST and MYSQL_MASTER_PORT are the addresses and ports of the master node. MYSQL_MASTER_USER and MYSQL_MASTER_PASSWORD are the username and password for connecting to the master node.

Step 4: Start the container cluster

After saving and exiting the file, use the following command to start the container cluster:

$ sudo docker-compose up -d

You can use the -d parameter to enable Containers run in the background.

Step 5: Verify container status

Use the following command to view the status of the container:

$ sudo docker-compose ps

You can see that the status of the container is running, which means The container is running fine.

Step 6: Test the container cluster

Now, you can test whether the MySQL container cluster is working properly. First, connect to the master node of the MySQL container and create a test database:

$ sudo docker exec -it mysql1 mysql -uroot -p
Enter password: your_password
mysql> CREATE DATABASE test;
mysql> EXIT;

Then, connect to the slave node and verify whether the data on the master node can be read:

$ sudo docker exec -it mysql2 mysql -uroot -p
Enter password: your_password
mysql> USE test;
mysql> SELECT * FROM your_table;
mysql> EXIT;

Among them, your_table is the name of the table you created on the primary node.

Through the above steps, a highly available MySQL container cluster has been successfully built. By replicating the data of the master node on multiple slave nodes, data redundancy and high availability can be achieved. If the master node fails, a new master node can be elected from the slave nodes and continue to provide services.

I hope this article can help you build a highly available MySQL container cluster on Linux. I wish you success!

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