Bug #96150 'show salve status' show the Inaccurate Last_IO_Error message
Submitted: 10 Jul 8:15 Modified: 10 Jul 11:34
Reporter: songlei wang Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Replication Severity:S3 (Non-critical)
Version:8.0.16 OS:CentOS
Assigned to: CPU Architecture:Any
Tags: replication

[10 Jul 8:15] songlei wang
Description:
 Change master need parameter MASTER_SSL or GET_MASTER_PUBLIC_KEY to build a secure connection when the user' auth plugin is caching_sha2_password, or io_thread will connect to server  failed after starting slave.

if the replication with caching_sha2_password account start failed due to insecure connection, the show slave status just show "Last_IO_Error: error connecting to master 'repl@127.0.0.1:18001'". error-log also has no Specific information about it.

we can not know why connecting to master failed.

How to repeat:
1. create replication user in master
master:
CREATE USER 'repl'@'%' IDENTIFIED BY 'repl';
grant REPLICATION CLIENT,REPLICATION SLAVE on *.* to 'repl'@'%';

2. change master(insecure connection)
slave:
 CHANGE MASTER TO 
  MASTER_HOST = '127.0.0.1', 
  MASTER_USER = 'repl', 
  MASTER_PASSWORD = 'repl', 
  MASTER_PORT = 3306, 
  MASTER_AUTO_POSITION = 1;

3. start slave;
4. show slave status
the Last_IO_Error will show "error connecting to master 'repl@127.0.0.1:18001'"

refer to https://bugs.mysql.com/96149
if we connect to server successfully using the user 'repl' before, then 'start slave' will success. The replication will work well both with caching_sha2_password account and insecure connection.

Suggested fix:
'show slave status' show the proper error messge just like "Authentication plugin 'caching_sha2_password' reported error: Authentication requires secure connection."
[10 Jul 11:34] Umesh Shastry
Hello songlei wang,

Thank you for the report.

regards,
Umesh