MySQL InnoDB Cluster on Docker

README.md

Testing MySQL InnoDB Cluster with Docker

1. Spin up the cluster

docker-compose up -d
docker-compose exec mysql1 mysqlsh -f /init.js

2. Test access to the cluster

# test access to read/write instance, should be always mysql1
docker-compose exec router mysql -h 127.0.0.1 -P 6446 -e 'SELECT @@hostname'

# test access to read only instance, should be round robin of mysql2 and mysql3
docker-compose exec router mysql -h 127.0.0.1 -P 6447 -e 'SELECT @@hostname'

3. Try dropping a read only node

# kill a read only node
docker-compose kill mysql3

# the log should show that:
# - 'Member with address mysql3:3306 has become unreachable.
# - 'Members removed from the group: mysql3:3306'
docker-compose logs -f --tail 10 mysql2

# read only access is now provided by mysql3 solely
docker-compose exec router mysql -h 127.0.0.1 -P 6447 -e 'SELECT @@hostname'

# restore the node
docker-compose up -d mysql3

# the log should show that:
# - 'The member with address mysql3:3306 was declared online within the replication group.'
docker-compose logs -f --tail 10 mysql2

4. Try dropping the primary node

# kill the primary node
docker-compose kill mysql1

# the log should show that:
# - 'Member with address mysql1:3306 has become unreachable.
# - either mysql2 or mysql3 becomes the new primary
docker-compose logs -f --tail 10 mysql2

# read/write access is now provided by mysql2
docker-compose exec router mysql -h 127.0.0.1 -P 6446 -e 'SELECT @@hostname'

# restore the node
docker-compose up -d mysql1

# the log should show that:
# - 'The member with address mysql1:3306 was declared online within the replication group.'
docker-compose logs -f --tail 10 mysql2

# read only access should be round robin of mysql1 and mysql3
docker-compose exec router mysql -h 127.0.0.1 -P 6447 -e 'SELECT @@hostname'

config-client.cnf

[client]
user=root
password=root

config-server.cnf

[mysqld]
gtid-mode=ON
enforce-gtid-consistency=ON
default-authentication-plugin=mysql_native_password

docker-compose.yml

version: '3'

services:
  mysql1:
    image: mysql/mysql-server:8.0.22
    container_name: innodb-cluster_mysql1
    hostname: mysql1
    environment:
      - MYSQL_ROOT_HOST=%
      - MYSQL_ROOT_PASSWORD=root
      - PEER_HOSTS=mysql2 mysql3
    command: --server_id=1
    volumes:
      - ./config-server.cnf:/etc/mysql/my.cnf
      - ./config-client.cnf:/root/.my.cnf
      - ./data/mysql1:/var/lib/mysql
      - ./init.js:/init.js
    restart: on-failure

  mysql2:
    image: mysql/mysql-server:8.0.22
    container_name: innodb-cluster_mysql2
    hostname: mysql2
    environment:
      - MYSQL_ROOT_HOST=%
      - MYSQL_ROOT_PASSWORD=root
    command: --server_id=2
    volumes:
      - ./config-server.cnf:/etc/mysql/my.cnf
      - ./config-client.cnf:/root/.my.cnf
      - ./data/mysql2:/var/lib/mysql
    restart: on-failure

  mysql3:
    image: mysql/mysql-server:8.0.22
    container_name: innodb-cluster_mysql3
    hostname: mysql3
    environment:
      - MYSQL_ROOT_HOST=%
      - MYSQL_ROOT_PASSWORD=root
    command: --server_id=3
    volumes:
      - ./config-server.cnf:/etc/mysql/my.cnf
      - ./config-client.cnf:/root/.my.cnf
      - ./data/mysql3:/var/lib/mysql
    restart: on-failure

  router:
    image: mysql/mysql-router:8.0.22
    container_name: innodb-cluster_router
    hostname: router
    environment:
      - MYSQL_HOST=mysql1
      - MYSQL_PORT=3306
      - MYSQL_USER=root
      - MYSQL_PASSWORD=root
      - MYSQL_INNODB_CLUSTER_MEMBERS=3
    ports:
      - "6446:6446"
      - "6447:6447"
    volumes:
      - ./config-client.cnf:/root/.my.cnf
    restart: on-failure

init.js

#!/usr/bin/mysqlsh -f
const CLUSTER_NAME = 'MY_CLUSTER';
const PASSWORD = os.getenv('MYSQL_ROOT_PASSWORD');
const PEER_HOSTS = os.getenv('PEER_HOSTS').split(/\s+/);

print('Connecting...\n');
shell.connect('root@127.0.0.1', PASSWORD);

try {
    print('Creating cluster...\n');
    let cluster = dba.createCluster(CLUSTER_NAME);
    os.getenv('PEER_HOSTS').split(/\s+/).forEach(host => {
        print('Adding ' + host + ' to the cluster');
        cluster.addInstance({
            host: host,
            password: PASSWORD
        }, {
            recoveryMethod: 'Clone'
        });
    });
    print('Cluster created\n');
} catch {
    print('Fail to create cluster. Trying to reboot cluster...\n');
    dba.rebootClusterFromCompleteOutage(CLUSTER_NAME, {
        rejoinInstances: PEER_HOSTS
    });
    print('Cluster rebooted\n');
}