Preparing Mount Points

Create directories for persistent configuration and data storage:

mkdir -p /opt/mysql-instance/{conf,storage}

Configuring Character Sets

Create the configuration file at /opt/mysql-instance/conf/custom.cnf:

[mysqld]
user=mysql
character-set-server=utf8mb4

[client]
default-character-set=utf8mb4

[mysql]
default-character-set=utf8mb4

Pulling the MySQL Image

List local images:

docker images

Search for available MySQL images:

docker search mysql

Pull a specific version (5.7 recommended for stability):

docker pull mysql:5.7

Or pull the latest version:

docker pull mysql

Creating the Startup Script

Create a script file at /opt/mysql-instance/start.sh:

#!/bin/bash
docker run -d \
  --name mysql-server \
  -p 3306:3306 \
  -e MYSQL_ROOT_PASSWORD=SecurePassword123 \
  -v /opt/mysql-instance/conf/custom.cnf:/etc/my.cnf \
  -v /opt/mysql-instance/storage:/var/lib/mysql \
  --restart=unless-stopped \
  mysql:5.7

The backslash (\) must be followed by an actual newline character, not spaces.

Parameter Reference

-d: Run container in detached mode (background)
-i: Interactive mode
-t: Allocate a pseudo-TTY
-p: Port mapping (host:container)
-e: Environment variables
-v: Volume mounts (host_path:container_path)
--name: Container identifier
--restart: Boot policy

Restart Policies Explained

Policy	Behavior
no	Never restart (default)
on-failure	Restart on non-zero exit code
on-failure:N	Restart up to N times
always	Always restart
unless-stopped	Restart unless manually stopped

The always policy ensures the container starts after Docker daemon restart. The unless-stopped policy differs in that stopped containers remain stopped after daemon restart.

Apply the script:

chmod +x /opt/mysql-instance/start.sh
./start.sh

Update an existing container's restart policy:

docker update --restart=unless-stopped mysql-server

Runtime Error Resolution

If encountering the cgroup configuration error:

container_linux.go:235: starting container process caused 
"process_linux.go:258: applying cgroup configuration..."

Update the system and restart:

yum update -y
systemctl restart docker

Verifying the Installation

Check running containers:

docker ps | grep mysql

Access the container shell:

docker exec -it mysql-server bash

Connect to MySQL:

mysql -uroot -pSecurePassword123

Exit using exit command twice (once for MySQL, once for shell).

Enabling Remote Access

Security Group Configuration

Add an inbound rule for port 3306 in your cloud provider's security group settings.

Granting Remote Privileges (MySQL 8.0+)

Switch to the mysql database:

USE mysql;

Query existing users:

SELECT host, user FROM mysql.user;

Create a remote-accessible root user:

CREATE USER 'admin'@'%' IDENTIFIED BY 'StrongPassword456';
GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%';
FLUSH PRIVILEGES;

Note: MySQL 8.0+ uses a different syntax for privilege grants than older versions.

Authentication Plugin Adjustment

MySQL 8.0+ uses caching_sha2_password by default. Some clients require mysql_native_password:

ALTER USER 'admin'@'%' IDENTIFIED BY 'StrongPassword456' PASSWORD EXPIRE NEVER;
ALTER USER 'admin'@'%' IDENTIFIED WITH mysql_native_password BY 'StrongPassword456';
FLUSH PRIVILEGES;

Modifying Exposed Ports

To change the external port (e.g., avoiding port 3306 for security):

1. Stop the container and Docker:

docker stop mysql-server
systemctl stop docker

2. Edit /var/lib/docker/containers/{container_id}/hostconfig.json:

"PortBindings":{"3306/tcp":[{"HostIp":"","HostPort":"3307"}]}

3. Edit the corresponding config.v2.json to update ExposedPorts and Ports sections.

4. Restart Docker and the container.