Policyd (cbpolicyd) Failure After upgrading MariaDB on AlmaLinux 8 / 9 with CWP

This phenomenon typically occurs after a MariaDB upgrade.

Typical log fragments in the maillog:

warning: connect to 127.0.0.1:10031: Connection timed out
warning: problem talking to server 127.0.0.1:10031
451 4.3.5 Recipient address rejected: Server configuration problem
install_driver(mysql) failed: Can't locate DBD/mysql.pm

This indicates that cbpolicyd (Cluebringer) cannot load the required Perl database driver.

Root Cause

Policyd relies on a Perl DBI driver to connect to its MariaDB/MySQL backend. If the DBD::mysql module is removed or mismatched, Policyd child processes exit with status 2, and Postfix rejects all RCPT requests due to policy service timeout.

AlmaLinux 8 vs AlmaLinux 9 Behavior

AlmaLinux 8 (EL8)

• Policyd requires:
  perl-DBD-MySQL

• The configuration remains in /etc/cbpolicyd/cbpolicyd.conf

DSN=DBI:mysql:database=postfix_policyd;host=localhost

Installing perl-DBD-MySQL resolves the issue.

AlmaLinux 9 (EL9)

EL9 introduces a packaging change where installing perl-DBD-MySQL may attempt to pull MySQL 8 libraries that conflict with MariaDB.

Instead, install:

dnf install perl-DBD-MariaDB

Then update the Policyd configuration:

Edit:

/etc/cbpolicyd/cbpolicyd.conf

Replace:

DSN=DBI:mysql:database=postfix_policyd;host=localhost

With:

DSN=DBI:MariaDB:database=postfix_policyd;host=localhost

This forces Policyd to load the DBD::MariaDB driver instead of DBD::mysql.

After modification:

systemctl restart cbpolicyd
systemctl restart postfix

Key Takeaway

• EL8 → install perl-DBD-MySQL

• EL9 → install perl-DBD-MariaDB and change the DSN driver in /etc/cbpolicyd/cbpolicyd.conf

Failure to update the DSN on EL9 will cause continuous Policyd crashes and complete mail flow disruption.

This distinction is critical for maintaining stable CWP mail servers after MariaDB upgrades or package maintenance.