Database connection fails if socket is used.

It seems that socket information ist not propagated from ezpublish5/vendor/zetacomponents/database/src/handlers/mysql.php to /ezpublish5/ezpublish_legacy/lib/ezdb/classes/ezmysqlidb.php

Setting the $socket variable in ezpublish5/vendor/zetacomponents/database/src/handlers/mysql.php line 70 circumvents the problem.

It should also be noted that the socket information is not present in ezpublish.yml, although it was present in settings/overried/site.ini.append.php