How to Build a MySQL Master‑Slave Replication Environment with Docker‑Compose

Preface

This article records how to use docker-compose and Dockerfiles to build a binlog‑based MySQL master‑slave environment. Follow the steps precisely and you should be able to set up a basic MySQL replication setup quickly.

Introduction

MySQL master‑slave synchronization consists of five steps:

The master writes data changes to the binary log.

The slave starts an I/O thread to request logs from the master after a specific position.

The master’s binlog dump thread pushes the requested logs to the slave.

The slave’s I/O thread writes the received logs to a relay log file.

The slave’s SQL thread reads the relay log, converts entries to SQL statements, and replays them on the slave database to keep data consistent.

Configuration

Create Directory Structure

First set up the directory layout as shown below. If you use a different layout, adjust the paths in docker-compose.yaml and the Dockerfiles accordingly.

Docker‑Compose Template

version: "3"
services:
  mysql-master:
    build:
      context: ./
      dockerfile: mysql/master/Dockerfile
    container_name: mysql-master
    volumes:
      - ./mysql/master/data:/var/lib/mysql
    restart: always
    ports:
      - 3305:3306
    links:
      - mysql-slave
  mysql-slave:
    build:
      context: ./
      dockerfile: mysql/slave/Dockerfile
    container_name: mysql-slave
    volumes:
      - ./mysql/slave/data:/var/lib/mysql
    restart: always
    ports:
      - 3306:3306

Master Node Configuration

cluster.cnf

[mysqld]
server_id=100
binlog-ignore-db=mysql
log-bin=replicas-mysql-bin
binlog_cache_size=1M
binlog_format=mixed
slave_skip_errors=1062
default_authentication_plugin=mysql_native_password
character-set-server=utf8mb4
collation-server=utf8mb4_unicode_ci

Dockerfile

FROM mysql:latest
ADD ./mysql/master/cluster.cnf /etc/mysql/conf.d/cluster.cnf
ENV MYSQL_ROOT_PASSWORD=password

Slave Node Configuration

cluster.cnf

[mysqld]
server_id=101
binlog-ignore-db=mysql
binlog_cache_size=1M
binlog_format=mixed
slave_skip_errors=1062
relay_log=replicas-mysql-relay-bin
log_slave_updates=1
read_only=1
default_authentication_plugin=mysql_native_password
character-set-server=utf8mb4
collation-server=utf8mb4_unicode_ci

Dockerfile

FROM mysql:latest
ADD ./mysql/slave/cluster.cnf /etc/mysql/conf.d/cluster.cnf
ENV MYSQL_ROOT_PASSWORD=password

Create Containers

docker-compose up -d mysql-master mysql-slave

If the build takes too long, you can switch to a faster mirror source, such as:

NetEase: http://hub-mirror.c.163.com

Alibaba Cloud: http://your-id.mirror.aliyuncs...

USTC: http://docker.mirrors.ustc.edu.cn

After the containers start, run docker ps to verify they are running as expected.

Configure Slave Node

Enter the mysql-master container and run: show master status; Note the File and Position values; they will be used on the slave.

Then enter the mysql-slave container and execute:

CHANGE MASTER TO
    MASTER_HOST='mysql-master',
    MASTER_USER='root',
    MASTER_PASSWORD=your_password,
    MASTER_LOG_FILE='[File from previous step]',
    MASTER_LOG_POS=[Position from previous step];
START SLAVE;
SHOW SLAVE STATUS \G;

Test Replication

Log into the master, create a new database, then log into the slave and run show databases;. If the new database appears on the slave, replication is successful.