Lua doesn't load the MySQL driver

[Bjoern Schiessle <bjoern@schiessle.org>]

Hi,

I run the XMPP server Prosody on a Debian server which I recently
updated to Buster. Since the update the Prosody server refuses to
connect to the MariaDB database. The log shows following error:

Nov 30 22:09:15 sql debug   Connecting to [MySQL] prosody...
Nov 30 22:09:15 sql debug   Database connection was closed. Will
reconnect and retry.
Nov 30 22:09:15 sql debug   Retrying SQL transaction
[function(mod_storage_sql.lua:137)]
Nov 30 22:09:15 sql debug   Connecting to [MySQL] prosody...
Nov 30 22:09:15 sql debug   SQL transaction retry failed
Nov 30 22:09:15 sql error   Error in SQL transaction:
/usr/local/share/lua/5.2/DBI.lua:53: Cannot load driver MySQL.
Available drivers are: SQLite3

It looks like the MySQL driver is not installed. But both packages,
"lua-dbi-mysql/stable,now 0.7.1-2 amd64" and "lua-sql-mysql/stable,now
2.3.4-1+b1 amd64" are installed.

If I install additionally "lua-dbi-postgresql" the last error message
changes to:

Nov 30 22:09:15 sql error   Error in SQL transaction:
/usr/local/share/lua/5.2/DBI.lua:53: Cannot load driver MySQL.
Available drivers are: SQLite3, PostgreSQL

Therefore I assume that the lua-dbi-* packages are the right one. But
for some reasons the MySQL driver is not detected/installed correctly.

I don't think it is a Prosody issue as the error seems to happen in the
Lua code.

Do I have to install an additional package to make it work? Does anyone
here experienced a similar issue with Buster?

Lua Version is 5.2.4 and Prosody 0.11.2.

Thanks!
Bjoern