version: '3.5'
services:
  alpha:
    image: mysql/mysql-server:8.0
    container_name: alpha
    hostname: alpha
    ports:
      - '1441:3306'
    restart: unless-stopped
    # sets the network address which the member provides for connections from other members,
    # specified as a host:port formatted string.
    command: [ "mysqld",
      "--loose-group-replication-local-address=alpha:6606" ]
    environment:
      MYSQL_ROOT_HOST: '%'
      MYSQL_USER: root
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: db_name
    volumes:
      - ./configs/my-cnf:/etc/mysql/my.cnf
      - ./scripts:/docker-entrypoint-initdb.d
    healthcheck:
      test: "mysqladmin ping -u root -p$${MYSQL_ROOT_PASSWORD}"
      interval: 2s
      retries: 20
...
   gamma:
    image: mysql/mysql-server:8.0
    container_name: gamma
    hostname: gamma
    ports:
      - '1443:3306'
    restart: unless-stopped
    # sets the network address which the member provides for connections from other members,
    # specified as a host:port formatted string.
    command: [ "mysqld",
      "--loose-group-replication-local-address=gamma:6606" ]
    environment:
      MYSQL_ROOT_HOST: '%'
      MYSQL_USER: root
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: db_name
    volumes:
      - ./configs/my-cnf:/etc/mysql/my.cnf
      - ./scripts:/docker-entrypoint-initdb.d
    healthcheck:
      test: "mysqladmin ping -u root -p$${MYSQL_ROOT_PASSWORD}"
      interval: 2s
      retries: 20

[mysqld]
# To be able to conect to db via Mysql Workbench/SequelPro/other UI tools
# It is not recommended to use the mysql_native_password authentication plugin for new installations that require high password security.
default_authentication_plugin     = mysql_native_password
# Binary log file name (for data recovery after possible mysql server crash).
log_bin                           = mysql-bin-1.log
# The MySQL Server system variables described in this section are used to monitor and control Global Transaction Identifiers (GTIDs).
enforce_gtid_consistency          = ON
# Controls whether GTID based logging is enabled and what type of transactions the logs can contain/# enforce_gtid_consistency must be true before you can set gtid_mode=ON.
gtid_mode                         = ON
# Whether updates received by a replica from a replication source server should be logged to the replica's own binary log.
log_slave_updates                 = ON
# When binlog_checksum is disabled (value NONE),
# the server verifies that it is writing only complete events to the binary log
# by writing and checking the event length (rather than a checksum) for each event.
binlog_checksum                   = NONE
# The setting of this variable determines whether the replica records source metadata, consisting of status and connection information,
# to an InnoDB table in the mysql system database, or to a file in the data directory.
# default value - TABLE
master_info_repository            = TABLE
# The setting of this variable determines whether the replica server logs its position in the relay logs
# to an InnoDB table in the mysql system database, or to a file in the data directory.
# default value - TABLE
relay_log_info_repository         = TABLE
# This option tells the server to load the named plugins at startup.
# In our case this is group_replication plugin
plugin-load-add                   = group_replication.so
# Load this plugin in case when server bin logs are too far away / removed.
# So group replication makes a clone of the current master (dump) and continue replication as default.
plugin-load-add                   = mysql_clone.so
# If enabled, this variable enables automatic relay log recovery immediately following server startup.
# The recovery process creates a new relay log file, initializes the SQL thread position to this new relay log,
# and initializes the I/O thread to the SQL thread position.
relay_log_recovery                = ON
# For Group Replication, transaction_write_set_extraction must be set to XXHASH64.
# The process of extracting the writes from a transaction is used in Group Replication
# for conflict detection and certification on all group members.
transaction_write_set_extraction  = XXHASH64
# Whether the server should start Group Replication or not during server start.
loose_group_replication_start_on_boot                    = OFF
# The name of the group which this server instance belongs to.# Must be a valid and _uniq_ UUID.
# This UUID is used internally when setting GTIDs for Group Replication events in the binary log.
loose_group_replication_group_name                       = aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee
# A list of group members to which a joining member can connect to obtain details of all the current group members.
# The joining member uses these details to select and connect to a group member to obtain the data needed for synchrony with the group.
# The list consists of the seed member's network addresses specified as a comma separated list, such as host1:port1,host2:port2.
loose_group_replication_group_seeds                      = alpha:6606,beta:6606,gamma:6606
# Instructs the group to automatically pick a single server to be the one that handles read/write workload.
# This server is the PRIMARY and all others are SECONDARIES.
loose_group_replication_single_primary_mode              = ON
# Enables or disables strict consistency checks for multi-primary update everywhere.
# The default is that checks are disabled. In single-primary mode, this option must be disabled on all group members.
loose_group_replication_enforce_update_everywhere_checks = OFF

CALL set_as_master;

SET @@GLOBAL.group_replication_bootstrap_group=1;
create user IF NOT EXISTS 'repl'@'%';
GRANT REPLICATION SLAVE ON . TO repl@'%';
flush privileges;
change master to master_user='root' for channel 'group_replication_recovery';
START GROUP REPLICATION;

SELECT * FROM performance_schema.replication_group_members;

CALL set_as_slave;

change master to master_user='repl' for channel 'group_replication_recovery';
START GROUP_REPLICATION;
# There should be no possibility to change anything in slaves
# since any inconsistencies will cause an errors with the next replication
SET @@global.read_only=1;

SELECT * FROM performance_schema.replication_group_members;