MySQL replication fails with permission error for unknown reason

Question

Since 36h I'm struggling to setup a simple Master <-> Master replication with MySQL 8. None of the found solutions on the Internet works here and meanwhile I'm a bit desperate. Even the first Master -> Slave replication wont work. So I hope for your help.

How does the environment looks like:

• Master and Slave are running on separated machines
• MySQL runs in a docker (the latest official MySQL image) on port 33060
• hosts are managed by/with Plesk Obsidian

MySQL configuration on both machines

[mysqld]
skip-host-cache
skip-name-resolve
datadir=/var/lib/mysql
socket=/var/run/mysqld/mysqld.sock
secure-file-priv=/var/lib/mysql-files
user=mysql

pid-file=/var/run/mysqld/mysqld.pid

sql-mode=""

server-id                = 1    // 1 = master host, 2 = slave host
binlog_do_db             = dbsscm
gtid_mode                = ON
enforce-gtid-consistency = ON

[client]
socket=/var/run/mysqld/mysqld.sock
!includedir /etc/mysql/conf.d/

Master Setup

CREATE USER 'replicator'@'%' IDENTIFIED BY 'REPLIC-PW';
GRANT ALL PRIVILEGES ON *.* TO replicator@'%';
FLUSH PRIVILEGES;

Test master access via:

mysql --host=MASTER-IP --port=33060 -u replicator --password='REPLIC-PW'

Slave Setup

CREATE USER 'replicator'@'%' IDENTIFIED BY 'REPLIC-PW';
GRANT ALL PRIVILEGES ON *.* TO replicator@'%';
FLUSH PRIVILEGES;

Test slave access via:

mysql --host=SLAVE-IP --port=33060 -u replicator --password='REPLIC-PW'

The master sql-db is accessible via mysql --host ... or telnet from the slave host. The slave sql-db is accessible via mysql --host ... or telnet from the master host.

Setup Master -> Slave

On the slave host:

STOP SLAVE;

CHANGE MASTER TO
        MASTER_HOST = 'MASTER-IP',
        MASTER_PORT = 33060,
        MASTER_USER = 'replicator',
        MASTER_PASSWORD = 'REPLIC-PW',
        MASTER_AUTO_POSITION = 1;
        
START SLAVE;
SHOW SLAVE STATUS\G;

Problem - Last_IO_Errno: 2003

MySQL [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
            Slave_IO_State: Connecting to source
                Master_Host: MASTER-IP
                Master_User: replicator
                Master_Port: 33060
                Connect_Retry: 60
            Master_Log_File:
        Read_Master_Log_Pos: 4
            Relay_Log_File: 8f18893b5155-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File:
            Slave_IO_Running: Connecting
            Slave_SQL_Running: Yes
            Replicate_Do_DB:
        Replicate_Ignore_DB:
        Replicate_Do_Table:
    Replicate_Ignore_Table:
    Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
                Last_Errno: 0
                Last_Error:
                Skip_Counter: 0
        Exec_Master_Log_Pos: 0
            Relay_Log_Space: 157
            Until_Condition: None
            Until_Log_File:
                Until_Log_Pos: 0
        Master_SSL_Allowed: No
        Master_SSL_CA_File:
        Master_SSL_CA_Path:
            Master_SSL_Cert:
            Master_SSL_Cipher:
            Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 2003
                Last_IO_Error: error connecting to master 'replicator@MASTER-IP:33060' - retry-time: 60 retries: 10 message: Can't connect to MySQL server on 'MASTER-IP:33060' (110)
            Last_SQL_Errno: 0
            Last_SQL_Error:
Replicate_Ignore_Server_Ids:
            Master_Server_Id: 0
                Master_UUID:
            Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
        SQL_Remaining_Delay: NULL
    Slave_SQL_Running_State: Replica has read all relay log; waiting for more updates
        Master_Retry_Count: 86400
                Master_Bind:
    Last_IO_Error_Timestamp: 221129 07:22:21
    Last_SQL_Error_Timestamp:
            Master_SSL_Crl:
        Master_SSL_Crlpath:
        Retrieved_Gtid_Set:
            Executed_Gtid_Set: 50e65cd5-6ccf-11ed-9fbf-0242ac110003:1-12
                Auto_Position: 1
        Replicate_Rewrite_DB:
                Channel_Name:
        Master_TLS_Version:
    Master_public_key_path:
        Get_master_public_key: 0
            Network_Namespace:
1 row in set, 1 warning (0.000 sec)

What I have tried to solve?

• search Google and forums for more than 24h now
• remove/reset everything several times
• tried different user names and passwords for the "replicator"
• switched of the firewalls on Master & Slave hosts

Whatever I do - I always get the same Last_IO_Errno: 2003 error and I have no idea what else I can further do? BTW: The databases on the Master are running and are accessible for client applications via the MASTER-IP.

P.S.: I'm aware that I've yesterday posted a similar post. But the post contains far more details.

Answer 1

You are using the wrong port number in the CHANGE MASTER TO command

CHANGE MASTER TO
        MASTER_HOST = 'MASTER-IP',
        MASTER_PORT = 33060, <<=== Invalid Port Number
        MASTER_USER = 'replicator',
        MASTER_PASSWORD = 'REPLIC-PW',
        MASTER_AUTO_POSITION = 1;

Since the Master's my.cnf does not set port, the default port number is 3306.

CHANGE MASTER TO
        MASTER_HOST = 'MASTER-IP',
        MASTER_PORT = 3306,
        MASTER_USER = 'replicator',
        MASTER_PASSWORD = 'REPLIC-PW',
        MASTER_AUTO_POSITION = 1;

UPDATE 2022-11-29 10:53 EST

You have given out too many privileges to replicator@'%'

It should say this

CREATE USER 'replicator'@'%' IDENTIFIED BY 'REPLIC-PW';
GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO replicator@'%';
FLUSH PRIVILEGES;

Also, you just said

Well, I have multiple SQL-servers running on the machine and it's configured to port 33060. see also my test: mysql --host=MASTER-IP --port=33060 -u replicator --password='REPLIC-PW'

Please make sure to put the port definition under [mysqld] group header.

[mysqld]
port=33060

If it is not there, add it to my.cnf, please add it and restart mysqld

In addition, please telnet that port

telnet IPofMaster 33060

Make sure it is open