Can we select global variable value and change session variable only if global variable is of incorrect value ? And maybe don't set session variable our selves but only show warning

<arimdjonoks>
1) <sasha> suggested that we should not use the global variables in the library functions and advised to use functions to set local static variables instead.
2) We need to set the session variables ourselves since there is no other way we could shadow global session variables.
Users can easily miss the warning and then spend time trying to find why proxy hangs. Failing to start a proxy looks a simple and safe solution as this problem (mysql enforcing session variable access control) is very limited (only proxy used with mysql versions 8.0.14-8.0.17 are affected, the error is easy to recover from, issue is documented in the known issues ).

vso by global variable I mean:

select @@GLOBAL.auto_increment_increment;

arimdjonoks
The original problem ZBX-15484 was caused by a user already having global variables(used by their non-zabbix systems). We cannot just override them for zabbix.

Available in versions:

• pre-4.0.22rc1 4987cb4
• pre-4.4.10rc1 398991f
• pre-5.0.2rc1 1d8fa7f
• pre-5.2.0alpha1 251b02d

Updated documentation:

• Added to the known issues for 4.0, 4.4, 5.0, 5.2.

this was also hapenning when updating zabbix proxy to 5.0.1 (from 5.0.0 ) on mysql from rpm packages on centos8
<arimdjonoks> MySQL in some versions (8.0.14-8.0.17) requires extra privileges to set the increment options. This issue soon will be added to the known issues, but essentially you can either upgrade to use MySQL to the higher version than 8.0.17 or just grant zabbix this privilege:

grant SESSION_VARIABLES_ADMIN on *.* to 'zabbix'@'localhost';

thanks - the grant did solve it on proxy ( mysql version 8.0.17 )